s -XV-S-A 3L<\ I ' QUARTERLY JOURNAL OF SCIENCE, LITERATURE, AND ART. j( : *Uf^ JLC . , THE QUARTERLY^ JOURNAL LITERATURE, AND ART. .v^otW^- JULY TO DECEMBER, 1829. LONDON: HENRY COLBURN AND RICHARD BENTLEY, NEW BURLINGTON-STREET. MDCCCXXX. LONDON? Printed by William Clowes, Stamford- street. CONTENTS. Page On M. Hansteen's recent Magnetic Observations in Siberia, In a Letter to Professor Renwick, of New York, by Captain Edward Sabine, R.A., Secretary of the Royal Society, &c. . . 1 Experiments on the Force of the Earth's Magnetism. By Captain E. Sabine, &c. . . . .14 A remarkable Phenomenon of Sound, and of the conveyance of minutely divided Matter during the Eruption of Mount SoufFre in 1812. By John Hancock, M.D. . . .31 On Classifications of Rocks. By John Mac Culloch, M.D., F.R.S., &c. . . . . .34 Remarks on the Worari and Sirvatan. By John Hancock, M.D. 50 On a Method of Cultivating Plants in Walls, for Ornaments ; with a Catalogue of those which succeed under this treatment . 53 On the Construction of the Galvanic Battery. By Robert Green- how, Esq. t . . . ,71 A short Account of Experimental Researches on the Diffusion of Gases through each other, and their Separation by Mechanical Means. By Thomas Graham, A.M., F.R.S.E., Lecturer on Chemistry, Glasgow . . . • .74 Observations on the Oxidation of Phosphorus. By Thomas Gra- ham, A.M., &c. . '•. v . '*'' ., . . .83 Notice of a singular Inflation of a Bladder . . . .88 Account of an Apparatus for ascertaining the value of different Alkalis. By W. G. Colchester, Esq. . . .89 Memoir on the Mean Results of Observations; read before the Academy of Sciences, April 20, 1829. By M. Poisson . 91 On a Method of rendering Platina malleable. (The Bakerian Lec- ture.) By the late William Hyde Wollaston, M.D., F.R.S., &c. . . . . .97 On Acromatic Telescopes. By Signor G. Santini, Director of the Observatory at Padua . . . .106 Travels in Turkey, Egypt, Nubia, and Palestine, &c, in 1824, 5, 6, and 7. By R. R. Madden, Esq., M.R.C.S. (reviewed) . .113 Further Recommendations respecting the Use of Lights in the Cornish Fisheries. By J. Mac CuLLocri,M.D., &c. . . 133 On Cookery in general, and on the Works of Jarrin and Ude in particular . . . . . .137 List of the Works of the late Sir Humphry Davy, Dr. Wollaston, and Dr. Thomas Young . . . .149 CONTENTS. MISCELLANEOUS INTELLIGENCE. I. Mechanical Science. Page 1. Eccentricity of Saturn's Ring 161 2. Resistance in Space to the Motions of Heavenly Bodies ib. 3. New Method of measuring the Power of Telescopes . . .162 4. Brown's Active Molecules . ib. 5. Force of Running Water . . ib. 6. Geological Hammer . . . 163 7. Cement for Hard Stones, Por- celain, and Glass . . . ib. 8. On the Structure of Metals ib. 9. On the Solidiacation of Plaster 167 Page 10. Formula for reducing a Mercu- rial Thermometer in high Tem- peratures 168 11. Determination of the Mathema- tical Law, according to which the Elastic Force of Steam in- creases with the Temperature ib. 12. Destruction of Vermin in Ships by Steam 169 13. Preservation of Butter . .170 14. On the Dilatation of Stone . ib. 15. New Artificial Horizon . . 171 II. Chemical Science. 1. Application of a high Tempe- rature to the Evaporation of Liquids 2. On the specific Heat of Gases 3. Artificial Preparation of Ice 4. Odoriferous Lamp . 5. Electricity of the Solar Rays 6. Atomic Weights of Iodine and Bromine 7. Chloride and Iodide of Nitrogen 8. Action of Iron on Ammonia . 9. Effect of Muriatic and Sulphuric Acid on Hydrocyanic Acid . 10. Phosphorus in Vacuo . 11. On the composition of Phosphu- retted Hydrogen 12. Combustibility of Carbon in- creased by Platina and Copper 13. Carbazotic Acid and Carbazo- tate of Lead .... 14. Decomposition of Sulphates in Water by Organic Matters 15. Instantaneous Light Apparatus 16. On the Analysis of Borax 17. Sulphuret of Silicium . . 18. On the Production of Artificial Ultramarine .... 19. Adulteration of Chromate of Potash ; its Detection . • 20. Sympathetic Ink 21. On the Detection of small Quantities of Mercury . 22. On the Coloration of Golden Articles of Jewellery . . 172 23. 24. ib. ib. 25. 173 ib. 26. 27. 174 28. 175 ib. 29. m 30. %b. 31. ib. 32. 178 33. 179 34. 180 35. ib. 36. ib. 181 37. 182 38. ib. 39. ib. 183 40. 41. ib. Berzelius's Analysis of Platina Ores 184 On the Specific Gravity of Alloys, &c 185 On a peculiar Principle in Blood, &c 187 Preparation of Hartshorn Jelly 188 Braconnot's Indelible Ink . ib. Preparation of Morphia, without the use of Alcohol . . .189 On Vegetable Jelly or Pectic Acid ib. GlaucicAcid 191 On the Formation of Acids in Vegetables ib. Plumbagine, a new Vegetable Substance 192 Preparations of Oil in different Oleaginous Plants . ib. Colouring Matter of Lichen Rocella ib. Bark of the Soap Tree . .193 Chemical Analysis of Green Oranges ib. Chemical Analysis of the Mine- ral Waters of Gastrin . .194 Analysis of Ipecacuanha Branca, Root of the Viola Ipecacuanha Chemical Examination and Ana- lysis of the Flowers and Leaves of Yarrow 195 Researches respecting Platina 196 Crystallization of Sulphatedlron 197 ib. CONTENTS. III. Natural History. Page 1. Effects of the Sulphurets of Arsenic, &c. on the Animal System ...... 198 2. Decomposition of corrosive Sub- limate by Vegetable Bodies ib. 3. Poisoning by Acetate of Mor- phia, and Recovery . . ib. 4. Adulteration of Bread by Sul- phate of Copper .... ib. 5. Rosacic Acid in Human Urine 199 6. Leech Bites ib. 7. On the preparation of Food from Bones 200 8. Process for preserving Milk for any length of Time . . . 203 9. Theory of Phrenology . . ib. 10. Phosphorescence of the Sea . ib. 11. Wild Pigeons in North America ib. 12. Changes in Animals in South America 204 13. Natural History of the Mole 205 14. On the Red Snow of the Arctic Regions 206 15. On the Nemazoaires of M. Gail- Ion 207 Page 16. Gathering of Medicinal Roots 208 17. Drying of Plants .... 208 18. Myrrh 209 19. On the different Genera and Species confounded with Cin- chona 210 20. On the Duration of the Germi- native Power of the Seeds of Plants . . . . . .211 21. Influence of Chemical Solutions on Plants ... .212 22. Terrestrial Magnetism . . ib. 23. Destruction of the Caves in Franconia . . . . .213 24. Storms in the Department of theLoiret 214 25. Peculiar Phenomena of Hu- midity 215 26. Meteorology ..... ib. 27. Decomposition of Rocks . . 216 28. Swedish Iron ib. 29. Commerce of the Sandwich Isles, in 1828 .... ib. 30. Fortifications attributed to the Indians in North America . 217 Meteorological Table for June, July, and August 218 TO OUR READERS AND CORRESPONDENTS. The best answer to F. R. S. is the insertion of Dr. Wollaston's paper. All that is important in Mr. R.'s paper has been said fifty times by other persons. We cannot undertake to forward communications to other journals, and request in future that such letters may be franked. We have been obliged to postpone the insertion of the Wiseman Papers, in consequence of the lamented death of our correspondent, Mr. Wadd. We must decline the letter on Naval Affairs. We have seen Dr. Graham's Catechism : it is not so good as Parkes's ; and what is worse, is a piracy upon the title of that deservedly popular work. Just Published for the Use of Students, A COLLECTION OF CHEMICAL TABLES OF EQUIVALENTS j ALSO, OUTLINES OF GEOLOGY ; By W. T. Brande, F. R. S., &c. A New Edition of Mr. BftANDE'S MANUAL OF CHEMISTRY IS NOW IN THE PRESS. THE QUARTERLY JOURNAL OF SCIENCE, LITERATURE, AND ART. On M. Hansteeris recent Magnetic Observations in Siberia. In a Letter to Professor Renwick of New York. Somerset House, July 20, 1829. My dear Sir, I received a few days ago a letter from Professor Han- steen of Christiania, dated from Irkutsk in Siberia, in April last. M. Hansteen is travelling, as you know, at the expense of his King, and with the permission of the Emperor of Russia, for the purpose of observing the Magnetic Dip, Variation, and Inten- sity, over the whole of the north of Europe and of Asia; and of comparing the actual phenomena with the system of terres- trial magnetism propounded by himself, in his celebrated trea- tise entitled " Magnetismus der Erde." The observations that M. Hansteen has already made in the first year of his undertaking, and the conclusions which they establish in regard to the directions assumed by the isodynamic curves, or curves of equal magnetic intensity, are in the highest degree curious and important. In the letter with which he has favoured me, he has taken the trouble to communicate his observations in full detail, and has expressly permitted me to make every use of them that I may think proper, " especially when it may encourage to new undertakings and accordingly forward the science." Having been requested by you to super- intend the construction in this country of a part of the mag- netic instruments, designed for the expedition now preparing JULY— SEPT., 1829. B 2 Qn M. Hansteen's recent Magnetic by the government of the United States, for scientific re- searches in the southern hemisphere, I cannot anticipate a more favourable opportunity of turning to good account the infor- mation of which M. Hansteen has so liberally made me the depository. Since analogy would lead us to expect that a corresponding system of magnetism prevails in the two hemi- spheres of our globe, a knowledge of the arrangement of the system in the northern hemisphere may prove an important guide and direction for corresponding researches in the south- ern ; whilst the example of M. Hansteen's undertaking may stimulate, and his success is well calculated to encourage, those who are about to enter on a career honourable alike to them- selves and to the government under whose instructions they are employed. For some years past it has been the opinion of several per- sons who have attentively considered the subject, that a know- ledge of the general system of the magnetism of our globe is more likely to be attained by experiments on the relative intensity of the magnetic attraction in different parts of the earth's surface, than by observations on the Dip, or Variation, of the needle. In conformity with this opinion, M. Hansteen (without, however, neglecting to observe on all occasions the three phenomena conjunctively) has applied himself especially to trace the lines connecting those places on the globe, where a needle freely suspended in the magnetic direction, and drawn a certain number of degrees from rest, is found to make an equal number of vibrations around its point of rest in a given time. It was to be expected that these lines of equal inten- sity would arrange themselves systematically round the point or points in each hemisphere where the intensity was greatest : and, on the supposition that two such points would be found opposite to each other on the globe, one in the northern and the other in the southern hemisphere, that the isodynamic lines would form parallel circles, analogous to those of geographical latitude, progressively diminishing in intensity from the two points of maximum or poles, to the boundary circle of the two hemispheres, which circle, following the same analogy, might receive the appellation of the Magnetic Equator. Such was in fact the system, which, until the decisive discoveries which Observations in Siberia. 3 M. Hansteen has now made, appeared sufficiently conformable to the existing observations to receive their countenance and support. It had so happened that the previous observations, although extending widely over the magnetic parallels in the northern hemisphere, namely, from the least almost to the greatest intensity, were confined in respect to longitude to a space little more than the quarter of a hemisphere ; and to that quarter which is immediately opposite to the countries visited by M. Hansteen. Within the space that had been thus examined, the isodynamic curves appeared to arrange them- selves, with comparatively insignificant deviations, in parallel circles, around a point situated in the north-eastern part of Hudson's bay, and, as nearly as could be judged, about the in- tersection of the 60th degree of geographical latitude with the meridian of 80° west of Greenwich. That a system appa- rently so simple, so like the arrangement of induced magnet- ism in a sphere of iron, and corroborated by the approximation of results observed over a fourth part of a hemisphere, should have been viewed as likely to prove eventually the general system of the globe, is not surprising. It is the peculiar dis- tinction of M. Hansteen to have been led by a more careful consideration of the slight apparent deviations which have been noticed, and of the general disposition on the globe of the lines of Dip and Variation, to infer the existence of a second point of principal magnetic action in the northern hemisphere ; a fact, which by his recent observations must now be regarded as fully established ; the isodynamic curves being found to arrange themselves systematically around two points, one in Hudson's bay and one in Siberia ; and to be governed in the courses which they follow, partly by their distances respectively from those points, and partly by a disparity in the absolute attrac- tive force at the points themselves, the maximum intensity in Siberia appearing to be weaker than the maximum in Hud- son's bay. The accompanying sketch of the northern hemisphere may enable me to convey a more distinct notion of the arrangement of the isodynamic curves than could be done by description alone : the portions traced in unbroken lines mark the con- nexion between places at which an equal intensity has been B2 4 On M. Hansteen's recent Magnetic observed ; and those in dotted lines exhibit the supposed com- pletion of the curves, in parts of the hemisphere where the intensity has not been as yet examined. The portions which arrange themselves around the point in Hudson's bay are chiefly laid down from observations made by myself in two voyages of North-west discovery, those of 1818, and of 1819- 1820 ; — in a voyage in 1822 to the equatorial shores of the Atlantic, and to several of the islands in the Atlantic and Carib- bean seas, — and in a fourth voyage, in 1823, to Greenland, Spitzbergen, and Norway. Their prolongations around the point in Siberia are from the recent observations of M. Han- steen and the gentlemen who accompany him. A brief notice of each of the curves in succession will enable me to point out generally the places which have furnished their respective authorities. Observations in Siberia. 5 Commencing with the intensities of the highest order, the curve drawn through the countries surrounding Hudson's bay is laid down from observations made at occasional intervals, from Regent's inlet in the north-west quarter, by Baffin's in the north, to Davis' strait in the north-east ; and again at New York in the south. In places situated under this curve a needle, freely suspended, which required 300 seconds to perform a given number of vibrations (designated by n) in London, would perform the same number of vibrations (in integer numbers) in 269 seconds. In the space included by this curve, within which, except at New York, no observations have hitherto been made, it may be presumed that the intensity progressively in- creases until it attains its maximum at a central point, for the observations made in receding from the curve in different directions, namely at Melville island, in Greenland, and to the southward of New York, all manifest an opposite tendency. The observations of M. Hansteen have made known the re- appearance, in Siberia, of an equal intensity to that beneath the curve which has been just described $ forming a curve pro- bably similar in figure, but of smaller dimensions, around a point of maximum intensity situated in longitude 102° east of Greenwich (which is, as nearly as can be judged, 180° from the present position of the corresponding point in Hudson's bay) and in latitude apparently somewhat to the north of 60°, but which will be more particularly determined in the present summer. M. Hansteen has traced the southern band of this curve below the 60th parallel, from the Jenisei river on the west, to the longitude of 1L5° E. (25° east of the Jenisei), and latitude of 61°, where it pursues a direction nearly north and south. It may be remarked of the Siberian curve, that the space which it incloses is considerably less than the corre- sponding curve in America; a circumstance consistent with the supposition already noticed, that the maximum intensity in Siberia is inferior in attractive force to the maximum in Hud- son's bay : consequently, curves of equal intensity are encoun- tered at a less distance from the point of maximum in Siberia than in America. The second curve on the American side connects those places where the needle, introduced for illustration, would per- 6 On M. Hansteen's recent Magnetic form n vibrations in 278 seconds. The points which have deter- mined it are, Melville island, in the north-west ; several stations on the west side of Greenland from lat. 76° to lat. 60° in the north-east ; and finally, a greater intensity observed at New York and a lesser at the Havanna ; whence it is concluded that this curve intersects the seabord of the United States at an in- termediate point between those cities. A corresponding inten- sity has been traced by Dr. Erman of Berlin (who accompa- nied M. Hansteen to Siberia) from the mouth of the river Oby, in lat. 68° and long. 70° E., preserving nearly the direction of a meridian to lat. 60°, where it bends gradually to the east- ward, passes between Tobolsk and Narym, and has been ob- served at Kainsk, by M. Hansteen, on its way to its probable southern limit on the Atlantic side, a few degrees south of lake Baikal. The third curve is that in which the needle would perform n vibrations in 287 seconds. It is laid down from observations, 1st, at the Havanna ; 2d, at the Pendulum islands on the eastern side of Greenland, in latitude 74°.5, where a somewhat greater intensity was found ; and 3d, between Hammerfest near the north cape of Europe, and Spitzbergen. By M. Han- steen's observations it enters the continent of Europe between Archangel and Nova Zembla, and was crossed by him on the route from Moscow to Tobolsk, in 56° and 57° east longitude, and 57° and 58° latitude. The fourth curve is that in which the needle would make n vibrations in 297 seconds. Its tracing from observation com- mences, on the American side, near the island of Jamaica, where the time of vibration was 294 seconds. Crossing the Atlantic, it passes through the northern parts of the British islands, and enters Norway south of Bergen. It there became subject to M. Hansteen's observation, who has ascertained its northern limit (from whence it begins to bend to the southward) to be on the shores of the gulf of Bothnia, midway between Stockholm and Tornea. He has since traced its prolongation through St. Petersburg and Moscow. It is M. Hansteen's intention to commence the present sum- mer by descending the Jenisei to Touroukansk under the polar circle, in order to extend the tracing of the curve of greatest Observations in Siberia* 7 intensity ; to return to Krasnejark, and to cross, in a route from thence to the Caspian sea, the curves 278, 287, and 297, in their further prolongation to the south-east: whilst Dr. Erman, who quits him at Irkutsk, and is furnished with the necessary instruments, will proceed by Jakutsk and Ochotsk to Kamtchatka, in which route he expects again to cross the same curves, after they have passed their southern Asiatic limit, and resumed for a second time a north-easterly direction. These are all the curves of which M. Hansteen has ascer- tained the reappearance on the Asiatic side, those of lesser intensity passing altogether to the south of his present journey. 1 shall however briefly notice the remainder, in order to com- plete the sketch of the isodynamic curves in the northern hemisphere, as far as the observations will warrant. The next curve, in which the needle would make n vibrations in 308 seconds, was observed by M. Humboldt in 1800-1805, to pass near the cities of Mexico and Carthagena ; by myself in 1822, near TenerifFe ; and again by M. Humboldt at Madrid and in the south of France. The next, in which the needle would require 321 seconds for n vibrations, was observed both by M. Humboldt and myself on the South American shore of the Atlantic, near the 10th degree of north latitude ; and by my- self was ascertained to pass to the north of Port Praya in the Cape Verd islands. The next, in which the needle would make n vibrations in 335 seconds, was frequently observed by M. Humboldt in the interior and on the western side of Columbia. After crossing the Atlantic, it enters the continent of Africa somewhat to the south of the Gambia river, as is shewn by my observations at Bathurst, where the intensity was greater, and at Sierra Leone where it was less. The next, where the needle would require 351 seconds for n vibrations, was observed by M. Humboldt at Tompenda in Peru, on the western side of South America; at Maranham on the eastern side by myself; and on the African side of the Atlantic it enters the continent of Africa, south of Sierra Leone. Finally, the curve of least intensity which appears in this quarter of the northern hemi- sphere, is that in which the needle would require 370 seconds for n vibrations : in its progress from the southern hemisphere, (where it was observed by myself at Bahia and Ascension), it 8 On M. Hansteen's recent Magnetic crosses the Equator near the western coast of Africa, as shewn by my observations at the island of St. Thomas. We may hope that the further tracing of the curves, in the Asiatic quarter, which have not been subject to M. Hansteen's observations in Siberia, will ere long be accomplished by the scientific industry of British officers employed in India ; where a line through the British dominions, from Ceylon on the south, to the Himalaya mountains on the north, would probably in- tersect the curves designated respectively by 308, 321, 335, and 351 seconds, nearly at right angles to their course. Mr. David Douglas, well known to you as the enterprising traveller and successful naturalist, in the countries adjacent to the Columbia river and its tributaries, returns in September to the north-west coast of America, on an undertaking which will occupy him there many months. He will be well provided with instruments, and is practised in the modes of observation. He hopes to determine the magnetic phenomena from California in the south, to the furthest extent towards the north to which cir- cumstances may enable him to prosecute his researches ; and from the ocean on the west, occasionally to the Rocky moun- tains on the east. He will probably ascertain the situation on the western side of North America of the curves 287" and 297", and will approach 278", when at his eastern limits. But it is from travellers in the interior of the United States, and in the countries adjacent to the Slave lake and Coppermine river, that we must expect exact determinations of this in- teresting curve 278". Unquestionably, however, the space included by the innermost curve is the field for observations of the very highest importance on the subject of the magnetism of the globe; and as it is traversed annually under the direc- tion of the Hudson's bay Company, we may confidently hope, from the ready disposition which that Company has shewn, in so many instances, to promote scientific researches, that much time will not elapse before that really important journey will be performed by a person properly qualified, by previous practice, to observe with the precision necessary on so parti- cular an occasion. In regard to the great space in the northern hemisphere oc- cupied by the Pacific Ocean, the numerous islands with which Observations in Siberia. 9 it is interposed present points of observation of easier access than many parts of the respective continents. A commence- ment has already been made by Captain Lutke, commanding one of the Russian ships of war at present engaged in a scien- tific voyage. In a letter which I have received from him, dated from New Archangel (Norfolk Sound) in July, 1827, he has been so obliging as to communicate to me the results of several observations on the Magnetic Dip and Intensity, which he had found opportunities of making in his passage from Conception. I have not availed myself of these in the accom- panying sketch of the isodynamic curves, because I regard his communication as private until he shall have returned and made his own observations public. At the date of his letter he was on the point of sailing for Behring's strait and Kamtchatka, which voyage, as well as in his subsequent operations, he will doubtless have obtained results of great interest. If we now direct our attention to the southern hemisphere, we find nearly the whole field of enquiry untrodden. Of pub- lished observations, there are only those made by M. de Ros- sel, in the voyage of D'Enlrecasteaux, at Java, Amboyna, and Van Diemen's Land. Of observations made, but not yet pub- lished, there are, 1st, those of Captain de Freycinet, at several stations visited by the expedition under his command : of these no public account has yet, I believe, been given : 2d, those which are at present in progress by Captain King, who is en- gaged in the survey of the southern parts of South America. The results obtained by him in the first year of his survey have been received in England : they commence at Rio Janeiro, and are continued at intervals down the eastern coast as far as Port Famine : he will probably have since extended them to Con- ception on the western side, the limit of his survey in that quar- ter. The results transmitted will require some slight modifica- tions on his return to this country, to compensate for differences of temperature, &c. : but none that can interfere with their general effect in evidencing a progressively and rapidly increas- ing intensity, from the neighbourhood of Rio, where it corre- sponds with the curve marked 370" in the accompanying sketch, to the Straits of Magellan, where it is intermediate between the intensities designated by 278" and 287". The 10 On M. Hansteen's recent Magnetic observations of M. de Rossel indicate in like manner that at the period of his voyage, towards the close of the last century, the several intensities, from that represented by 370", to that represented by 278", were all comprised between Java in the north-west, and Van Diemen's Land in the south-east. Hence, as far as the evidence hitherto extends, it would appear that there are two points of maximum intensity in the southern as well as in the northern hemisphere : but the geographical posi- tion of those points, and their respective intensities, relatively to each other, and to the points of maximum in the northern hemisphere, remain to be determined, and must be acknow- ledged to be subjects of highly curious and important enquiry. In the arrangement of magnetism, as exhibited to us on the great scale of our globe, — differing, as it is now known to do, so widely from the analogies with which it had been associated, and indeed, I believe, from all analogy whatsoever with which we are acquainted, — we cannot too soon inform ourselves accu- rately of the facts. In selecting the parts of the southern hemisphere in which enquiries of this nature may be most advantageously pursued, regard must be paid, in the first instance, to the distribution of land, on account of the convenience which its coasts and islands afford in determining and connecting the isodynamic curves. The eastern and western coasts of New Holland, and the ad- joining island of New Zealand, — the western coast of South America from Lima to Cape Horn, and a continuation to the lands to the southward of Cape Horn approaching the Ant- arctic Circle, — the islands which might be successively visited in a course from the Cape of Good Hope to Desolation Island, and from thence to the Mauritius, — present in this view the directions of principal interest. Careful observations systema- tically made in them, combined with the observations already made, would advance our knowledge of the magnetic pheno- mena of the southern hemisphere to the same stage that it has attained in regard to those of the northern : viz. it would establish the number of the governing points of intensity in the hemisphere ; determine their respective geographical positions, and, in great measure at least, their relative intensities; ascertain the general arrangement of the curves ; and, finally, point out Observations in Siberia, 11 those localities of peculiar interest, which it might be expedient to visit for more particular enquiry. A single expedition might accomplish all this, without extending the duration of the voyage to an undue length, or interfering with other important objects of scientific research : and we may assuredly affirm, that were this service the single purpose, and sole object accom- plished, by a scientific expedition, it would of itself confer no ordinary distinction. In what has hitherto been said, observations made on land have alone been taken into account : the motion of a ship, and the quantity of iron necessarily employed in her equipment, impeding the prosecution of such researches at sea, and pre- senting embarrassments which, to say the least of them, are very difficult to surmount, and but too likely to impair the accuracy of the results. Still, when we consider how large & portion of the southern hemisphere is covered by the ocean, it does appear desirable to make the endeavour to obtain the best results, that circumstances will permit, over such extensive por- tions of the globe ; and particularly as in the opinion of those, who from experience are most competent to judge, it is possible, by great care, to obtain results worthy of confidence. M. Hum- boldt has recorded several observations which he made himself at sea, in the northern Atlantic, both of the Dip and of the Intensity, the latter of which accord well with the curves of intensity traced in the accompanying sketch. M. Hansteen believes, that by giving a dipping needle the sort of suspension used in Captain Cook's third voyage, — by choosing those times for observation when a calm sea and moderate wind allow the ship to keep a steady course, — by confining the use of the in- strument always to the same place on the ship's deck, — and by comparing the results on board and on shore on all occasions, when in harbour, — observations on board ship might become very valuable. I will venture to add an extract on this subject from Captain Lutke's letter, whose remarks are the more en- couraging as, when he quitted Europe, he was by no means sanguine of success in the use of delicate magnetic instruments at sea. " Je dois pourtant faire quelques remarques sur les observations faites a bord. J'avais ete, comme vous, en doute qu'elles puissent donner des resultats dignes de confiance, mais 12 On M. Hansteen's recent Magnetic Pexperience m'a appris, qu'en faisant choix d'un endroit assez eloigne de toute grande masse de matiere ferrugineuse, on peut atteindre a une precision sufFisante. Dans toutes mes relaches je n'ai jamais manque de comparer les indications des aiguilles a bord, a celles de terre. A Rio et a la Conception les resul- tats ont ete a. peu pres identiques ; ici (at Norfolk Sound) ou l'inclinaison comme la force ont atteint leurs maximum (c'est a dire pour nous) et par consequent ou l'influence du fersurles aiguilles — cscteris paribus — est aussi a son maximum, ici Pin- clinaison a bord ne differoit de celle a terre que d'un petit nom- bre de minutes ; Pintensite de la force indiquee par Paiguille verticale fut precisement la meme, et d'apres Paiguille hori- zontale un peu moindre. En consideVant que Pepreuve fut faite par les circonstances les plus desavantageuses, on con- viendra que les observations faites a bord meritent quelque confiance. Mais il est essentiel de mettre toute Pattention possible au choix du propre endroit; car voulant faire les ob- servations dans ma chambre, je n'etois parvenu qu'a des resul- tats tres fautifs." For experiments on the Magnetic Force, it is of the first necessity that the needles employed should retain throughout the same degree of magnetism ; or should undergo merely such slight and gradual alterations in that respect, as admit of cor- rections being applied by interpolation, from experiments made at the same spot before and after the series in which they have been employed. This property of the needles ought always to have been ascertained by previous trial during several months. Those which I send you belonged originally to M. Hansteen, and have been in my possession, and in constant use, for three years past: their magnetism has hitherto undergone a slight but very regular diminution from year to year, well admitting of interpolation. It will be proper, therefore, that observations should be made with them at the port from which the expedi- tion sails, a few days before its departure, and again in the same place, as soon as convenient after its return. It will also be proper that the needles should be then sent back to London, that observations may be repeated with them here, to ensure the connexion of the results obtained by their means, with those of the other experimentors which regard London, Paris, and Observations in Siberia. 13 Christiania, as their base. The needles should be kept apart from each other, and from contact with iron, and particularly with magnetised iron. I do not attempt in this letter to enter at any length on the consideration of the curves of Dip and of Variation. M. Han- steen has shewn, in the treatise already named, the general conformity of these phenomena to such an arrangement of magnetic attraction, as is indicated by the course of the isody- namic curves. His observations in Siberia, in as far as they go, confirm this view. Thus, for example, in the parallel of 55° north, the Dip, which in tracing the parallel to the east- ward progressively decreases from Labrador, where it exceeds 80°, is found by M. Hansteen to attain a minimum of 67°J, about the 42nd degree of longitude east of Greenwich ; from thence it increases, until the intersection of the parallel with the meridian of the Siberian maximum of intensity (102° E.), when its amount is 70°|: from that meridian it again decreases to a second minimum, by the observations of Russian officers, in the meridian of Kamtchatka (163° east). Hence, as regards the dip in the parallel of 55° N., there are two points of maxi- mum and two of minimum ; those of maximum are in the same geographical meridians, or nearly so, as the points of maximum intensity ; and those of minimum occur respectively in meri- dians 120° on either side of the Hudson's bay maximum, and G0° on either side of the Siberian maximum. In like manner, the variation, in the 55th parallel, is in the longitude of the minimum of Dip, 42° east ; is, easterly increasing, for the next 30° of longitude, and easterly decreasing, for the following 30° ; so that the variation becomes again in or about the meridian of 102 east, which is that of the Siberian maximum of inten- sity. In the sincere hope that this letter may be instrumental in promoting this highly curious and philosophical enquiry, which would be the best return I can make to M. Hansteen for his kind- ness in giving me so early and so full an account of the progress of his discoveries, I remain, my dear Sir, Very faithfully your's, Edward Sabine. 14 Captain Sabine's Experiments on the P. S. Since I wrote the above I have substituted a needle made some years ago by Mr. Dollond for myself, for one of the two which originally belonged to M. Hansteen, and which it was my first intention to have sent to you. You will perceive, by the memoranda accompanying the needles, that No. xx, the one I have substituted, has remained perfectly steady in its magnetism for a twelvemonth past, and will probably therefore continue so. No. xi, which I received from M. Hansteen three years ago, has increased its time of making 300 vibra- tions from 15' 46".l to 15' 52".7, since June, 1827, when the last published observations were made with it. Phil. Trans. 1828, Art. 1, page 14. Consequently, its magnetism has diminished, in two years, between one and two parts in one hundred. It will be prudent, however, to treat both needles as liable to further changes. Experiments on the Force of the Earth's Magnetism. By Capt. Edward Sabine, R. A., Secretary of the Royal Society. [Communicated by the Author.] The preceding letter to Mr. Renwick, respecting M.Hansteen's recent observations on the isodynamic magnetic curves in Russia and Siberia, contains also a general notice of all exist- ing observations on the same subject. Those of my own making, referred to in that letter, were published in 1825, in the volume containing the account of my Pendulum and other Experiments made in 1822 and 1823. That account con- tained the Dip of the Needle at nineteen stations, principally in the Northern Hemisphere, and the times of vibration of magnetic needles suspended horizontally, at the same stations. The times of vibration were not corrected for the effect of dif- ferences of temperature, arising from the widely different lati- tudes at which the observations were made, nor were they reduced to what the time would have been in infinitely small arcs. It also appeared, on comparing the times of vibration in London, before I left England and after my return, that the needles had not all preserved their magnetism unimpaired Force of the Earth's Magnetism. 15 during the interval, but that some had undergone slight changes in that respect. A mean between the first and last times of vibration was in such cases taken as the rate in London, cor- responding to that of the several foreign stations ; (the purpose being to compare the force at each of the stations to the force in London). A more strict comparison would obviously have required an interpolation of the times of vibration corresponding to each station in particular ; by computing the proportional part of the whole gain or loss due to the date at, the several stations. And more especially it would have required that reductions should have been applied for the arcs and for the differences of temperature. Since the first publication of those results, the subject of the magnetic intensity has increased in public interest, greatly owing to the writings and observations of M. Hansteen ; and an importance has, consequently, attached to my observations greater than I ventured to anticipate at the time. Shortly after their publication, M. de Humboldt, whose writings first excited my interest in the subject, kindly wrote me his opinion, that the minute corrections alluded to would not be, as I was disposed to consider, a refinement beyond the occasion : and M. Hansteen has since expressed the same opinion, in a review of the magnetic portion of my volume of experiments printed in PoggendorfF's Annalen der Physik. I have, therefore, for some time past, viewed the correction of the results as a duty to be performed whenever leisure and convenience should enable me to execute it ; and I had commenced the preliminary experiments for determining the amount of the correction for temperature for each needle, in the summer of last year. A short residence during the present summer, in the neighbourhood of the garden of the Horticul- tural Society at Chiswick, a spot exceedingly well calculated for such observations, has enabled me to complete them ; and I cannot take a better opportunity of making the corrected results public, than at the moment when M. Hansteen's journey to Siberia is adding so greatly to our knowledge of the facts in regard to the Magnetic Intensity, and, consequently, is drawing the public attention to the subject. 1 confine myself to the results obtained with the needles 16 Captain Sabine's Experiments on the numbered 3, 4, 5, and 6, as being those from which the most satisfactory conclusions can be drawn. In order to examine the effect of differences of temperature on the time of vibration, I placed a bell-glass receiver within- ?r side the box in which the needles vibrate, and fastened the silk, by which they were suspended, to the top of the receiver, which was perforated for that purpose. A thermometer was placed withinside the receiver, as near the needle as the space required for its vibration would permit. The box was then closed by the usual thick plate of glass at the top. In the apparatus thus arranged, a needle was first vibrated at the natural temperature of summer, about 65°. The glass plate was then removed, the space which is shaded in the wood-cut was filled with ice, and the plate replaced. When it appeared by the thermometer that a sufficient time had been allowed for the temperature withinside the receiver to become steady, the needle was again vibrated. On the following day, the experiment was repeated at the same hour and in the inverse order, the needle being first vibrated in the colder, and then in the warmer temperature. By this means, the difference in the time of vibration was obtained, corresponding to the usual summer heat of this country, and to more than 20° below it. To ascertain the correction for higher temperatures, the box was itself placed withinside a large garden-pot, sur- mounted by a garden glass. The hole in the bottom of the pot was enlarged, so that the flame of a spirit lamp entering the aperture, heated the air contained in the space between the box and the pot, and ultimately that contained within the box itself. Each of the needles were then successively vibrated, 1st, at the usual summer temperature ; 2d, at temperatures Force of the Earth's Magnetism. 17 from 40° to 50° higher ; and 3d, again when cooled to the summer temperature ; a mean being taken between the 1st and 3d, to compare with the 2d. With these arrangements, needle No. 3 made the time of 70 vibrations as follows : — August, 1828. In the ordinary temp., 19' 28".8 Th. 64°.5 In the cooled temp. .... In the cooled temp. .... In the ordinary temp., 19' 28".0 Th. 64°.0 19' 28".4 Th. 64°.25 19' 23".7 19' 22".8 Th. 40° Th. 47° July, 1829. In the ordinary temp., 19' 26". 1 Th. 67° In the heated temp. In the ordinary temp., 19' 26".4 Th. 68° 19' 23".25 Th. 43°.5 19' 35".07 Th. 116° 19' 26".25 Th. 67°5 19' 35".07 Th. 116° Whence we have, by the first mode of experiment, an increase of 5."15 in the time of vibration, caused by an increase of 20°. 75 in the temperature ; and by the second mode of expe- riment, an increase of 8".82 in the time, caused by an increase of 48°.5 in the temperature. Their sum, 13".97 -r 69°.25 = 0".2, the increase in the time of vibration for one degree of Fahrenheit; and 0".2 -J- 19' 28" = .00017, the multiplier for one degree. Then, if T be the time of vibration of this needle at an observed temperature t, and if it be required to know the JULY— SEPT., 1829. C 18 Captain Sabine's Experiments on the time T' in which the same number of vibrations would have been performed at any other temperature, t', adopted as a time of comparison, T'=T [1 ± .00017 (t — £')] ; the sign + being applicable when the observed temperature is lower than that adopted as a mean, and — when it is higher. By the same means, needle 4 was found to lessen the time of performing 170 vibrations 7".6 by a reduction of tempera- ture of 21°, from 62° to 41°; and to increase it 16".8 by an augmentation of temperature of 64°.5, from 57° to 121°. 5. The sum of the two experiments 24".4 -f. 85°.5 = 0".285, the increase for one degree of Fahrenheit ; and 0".285 -f- 15' 20" the time of 170 vibrations s -0003 the multiplier. For this needle, therefore, T'=T [1 ± -0003 (t-ty]. Needle 5 was found to lessen its time of performing 240 vibrations 20".25 by a reduction of 22°, from 64°.25 to 42°.25 ; and to increase the time 25".4 by an augmentation of 39°, from 68° to 107°. The sum of the two experiments 45".65 -f59°.25 =0".75, the increase for one degree of Fahrenheit ; and r/ .75 -f- 31' 07", the time of performing the 240 vibrations qa -0004, the multiplier. For this needle, therefore, V b= T [1 ± -0004 (t-t')~\. Needle 6 was found to lessen its time of performing 100 vibrations 2".78, by a reduction of 24°. 5, from 67°.5 to 43°; and to increase it 4". 51 by an augmentation of 48°, from 65° to 113°. The sum of the two experiments is 7".29 -f- 72°.5 = 0".l, the increase for one degree of Fahrenheit; and 0".l -r 10' 38", the time of performing 100 vibrations = -00016 the multiplier. For this needle, therefore, T' = T[1 ±.00016 (*-*')]• When observations with horizontal needles are widely ex- tended, so as to include a considerable range of intensity, and consequently much difference in the time of performing a given number of vibrations, it is not sufficient for the just relation of the results, that the vibrations should be made on all occa- sions in similar arcs : it is also necessary, in such case, that the time of vibration at each station should be increased to what it would have been had the vibrations been made in infinitely Force of the Earth's Magnetism. 19 mall arcs. I have taken for this correction the usual formula, m/ m/r-, sin. (A. + a )— sin. (A — a) _ , . . . T^rri+ oo km /i • x i — ^T". T being the ob- L 32 M. (log. sin. A.— log. sin. a) ' b served time of vibration, A and a the commencing and concluding arcs, and T' the time of vibration corrected for the arc. By comparing the corrections given by this formula with the vibrations in different arcs, I have ascertained that it repre- sents, with sufficient approximation, all the differences which are observed to take place. It was my usu il custom to com- mence the registry of the vibration when the arc was at 30°, and to continue it till the arc had diminished to 10°. In such case A =30° and a=10°, and the formula becomes T' a T -f- T . •0065. In some of the repetitions which I have made with the needles in London, I have begun and concluded with smaller arcs ; which exceptions to the usual custom will be expressly noticed in the cases which occur in the following pages. I proceed next to consider what should be regarded as the time of vibration of each needle, corresponding to the periods at which observations were made with it in different parts of the world. The times of vibration in London, in 1821, 1823, and 1824, uncorrected for temperature and the arcs, are given in the account of the experiments with horizontal needles (Pen- dulum and other Experiments, page 481). The original re- cord of the observations in 1821 and 1823, is still existing, and enables me to supply the necessary corrections, by furnishing a knowledge of the temperature and of the arcs. After the com- pletion of the experiments in 1824, the needles were laid by in pairs, each pair contained in a separate box with opposite poles united, and the boxes tied up together. In this state the needles remained for four years, until 1828, when they were taken out to have the corrections for temperature determined. By collecting in one view the several observations properly cor- rected made with each needle in London, we may readily examine and assign the rate of vibration corresponding to the periods at which the needles were used at foreign stations. Commencing with No. 3, we have in 1821. October. In the Regent's Park. Th. 55°. Arcs 20° to 5°. Rate 165".9 ; + 0".14 reduction to Th. 60°; + 0".41 to infinitely small arcs = 166".4. C 2 20 Captain Sabine's Experiments on the 1823. April. Horticultural Garden, Chiswick. Th. 42°. Arcs 30° to 10°. Rate 164".0 + 0".5 to Th. 60°+l".08 for Arcs = 165".6. 1828. March. In the Regent's Park. Th. 40°. Arcs 30° to 5°. Rate 1 63".52 + 0".56 + 0".7 1 = 1 64".8. 1828. August. Horticultural Garden, Chiswick. Th. 64°.5. Arcs 30° to 5°. Rate 166".9-0".12 + 0".71 = 167".5. 1829. July. Horticultural Garden, Chiswick. Th. 67°. Arcs 30° to 5°. Rate 166".6 - 0".22 + 0".71 = 167".l. 1821. October. Regent's Park 166".4j 1823. April. Chiswick 165".6j 166,0 1828. March. Regent's Park 164".8 > 1828. August. Chiswick 167".5 tl66.5 1829. July. Chiswick 167".l J Mean . 166".3 In the case of this needle, we may consider the differences from the mean rate as accidental deviations, occasioned pos- sibly, in part, by the observations having been made at different periods of the year, or at different hours of the day, or at dif- ferent spots, and in part, also, by the errors of observation, rather than as systematic alterations in the magnetism of the needle; and we may therefore regard 166" as the rate in Lon- don, corresponding to observations made elsewhere in the years 1822 and 1823. I have not attempted to introduce a correction for the period of the year at which the observations were made at the different stations, because I do not feel assured that we have sufficient evidence of the amount of the change which the magnetic force undergoes, in England, at different seasons of the year, inde- pendently of the effect on the needle itself of variations of temperature : and we have no satisfactory evidence whatsoever in regard to the monthly oscillations of the force, at any of the foreign stations. With respect to the hour of the day, all the observations, at every station, were made between the hours of noon and five P. M., excepting at Jamaica and Maranham, where, from accidental circumstances, they were necessarily made between six and nine A. M. No order of succession was preserved in making the observations, the needle that first presented itself being the first used : but any irregularities arising from this cause disappear in the mean result. With needle No. 4, we have in Force of the Earth's Magnetism. 21 1821, October, Regent's Park. Th. 55°, Arcs 20° to 2°. Rate 540".0 + 0".8+ 0".9 = 541".7. 1823, April, Chiswick. Th. 42°, Arcs 30° to 10°. Rate 532".4 + 2".9 + 3".5 = 538".8. 1828, March, Regent's Park. Th. 40°, Arcs 30° to 5°. Rate 534".l + 3''.2 + 2".3 = 539".6. 1828, September, Chiswick. Observed by Mr. David Douglas. Th. 64°.5, Arcs 30° to 5°. Rate 540".0 — 0".7 + 2".3 ■ 541".6. 1821, October, Regent's Park . . 541".7 1823, April, Chiswick .... 538".8 1828, March, Regent's Park . . 539".6 1828, September, Chiswick . . . 541 ".6 Mean . 540".4 In the case of this needle also, we may regard the mean 540".4 as the rate of vibration corresponding to all periods of the years 1822 and 1823. With needle No. 5 we have, in 1821, August, Regent's Park, Th. 60°, Arcs 20° to 5°. Rate 726".l + + 1".46 = 727".7. 1821, October, Regent's Park. Th. 55°, Arcs 20° to 5°. Rate 729".53 + 1".46 + 1".83 = 732".8. 1823, April, Chiswick. Th. 42°, Arcs 30° to 5°. Rate 743".7 + 5".36 + 3".23 = 752". 3. 1828, March, Regent's Park, Th. 48°, Arcs 30° to 5°. Rate 765".0 + 3". 6 7 + 3".32 = 772''.0. 1828, September, Chiswick. Observed by Mr. David Douglas. Th. 66°, Arcs 30° to 5°. Rate 769".4 — 1".84 + 3".34 = 770".9. 1829, July, Chiswick. Th. 68°, Arcs 30° to 5°. Rate 772".0 — 2".47 + 3".35 = 772".9. 1821, August, Regent's Park . . 727".7 1821, October, Regent's Park . . . 732".8 1823, April, Chiswick . . . 752".3 1828, March, Regent's Park . . . 772".0 1828, September, Chiswick . . . 770".9 1829, July, Chiswick .... 772".9 Hence we perceive that this needle gradually lost a portion of its magnetism in the years 1821, 1822, and 1823, and did not become stationary until some time between 1823 and 1828, and that the loss was more rapid in 1821 than in 1822 and 1823. If, then, we distribute the total increase in the time of vibration (19".5 in the eighteen months comprised between October 1821, and April 1823) into a monthly increase of 1".5 in each of the first three months of that period, and of V 22 Captain Sabine's Experiments on the in each of the other fifteen months, and continue an increase of0".5 in each of the remaining months of 1823, we shall make the best arrangement, perhaps, that circumstances will permit, for the rate of this needle in London corresponding to the observations made with it elsewhere. With needle No. 6 we have, in 1821, August, Regent's Park. Th. 60°, Arcs 20° to 2°. Rate 62i".12 + .0 + 0".98 = 622".l. 1821, October, Regent's Park. Th. 55°, Arcs 30° to 10°. Rate 619".5 + 0".63 + 4".02 - 624".0. 1823, April, Chiswick. Th. 42°, Arcs 30° to 5°. Rate 634".2 + 1".82 + 2".75 = 638".8. 1828, September, Chiswick. Observed by Mr. David Douglas. Th. 67°, Arcs 30° to 5°. Rate 636".9— 0".76 + 2".76 = 638".9. 1829, July, Chiswick. Th. 65°.5, Arcs 30° to 5°. Rate 637".0 — 0".56 + 2".76 = 63 9". 2. 1821, August, Regent's Park . . . 622".l 1821, October, Regent's Park . . . 624"»0 1823, April, Chiswick ...» 638".8 1828, September, Chiswick . . . 638".9 1829, July, Chiswick . . . 639".2 Hence we perceive that this needle also lost a portion of its magnetism between 1821 and 1823; but that it has been sta- tionary from April 1823, to the present time. If, then, we distribute the total increase in the time of vibration between October 1821 and April 1823, 14".8 in eighteen months, in the following manner, viz. — An increase of 1".5 in each of the first five months ; of 1" in each of the next five months ; and of 0".5 in each of the remaining eight months; we may consider the time of vibration in London during those months as satis- factorily represented by the interpolated rates. On a review of the degree of permanency with which the needles have preserved their magnetism, we perceive that three of them have undergone no alteration in that respect in the six years intervening between 1823 and 1829, during which time they have been kept in pairs, and the small boxes, each containing a pair, tied up together. This mode of keeping needles has the advantage of rendering them less liable to be injured by the accidental approach of iron or of a magnet, than if they were kept separately. Their being kept in pairs, also, probably contributes to preserve their magnetism unim- Force of the Earth's Magnetism. 23 paired, independently of guarding them against such accidents. Two of the needles have the same time of vibration now as when they were first employed in 1821 ; they are both simple bars ; one square at the ends, and the other pointed. A third increased its time of vibration about ^th part in the first two years, and has remained steady since ; it is cylindrical in shape, the ends not pointed. The fourth needle altered more, and was a longer time before it became steady than the others ; it is a bar, with square ends, but it differs from the other needles in being made (for experiment) of iron, with extremi- ties of hardened steel. Two such were made at the same time, and both have undergone greater changes, and have been longer in becoming stationary than needles of uniform hardness. To exemplify the manner in which the results with the several needles are brought in comparison with each other, and in relation to a fixed term of comparison in London, I take the first station at which the needles were all employed after I quitted England in 1821, namely at Sierra Leone, March 20, 1822, Th. 80°, Arcs 30° to 10°. Needle 3. Rate U9".76 — 0.41 to Th. 60° + 0.78 for arc = 120".13. Needle 4. Rate 389".3 — 2.34 '+ 2.53 = 389".5. Needle 5. Rate 535".6 — 4.28 + 3.47 = 534".8. Needle 6. Rate 456".7 — 1.46 + 2.96 = 458".2. The corresponding rates in London are, needle 3, 166" ; 4, 540".4; 5, 739".5; 6, 631".6. If then we take as a general mean term of comparison in London, to which the results at all stations should be referred, a needle which, freely suspended in the direction of the dip, would make its time of vibration 300", the same needle would have its time of horizontal vibration in London, (the dip in 1822- 1823 being 70°)^^ = 512".97. The time of hori- zontal vibration of this needle at Sierra Leone would then be, according to the several needles, as follows : — Needle 3. 166.0* ; 120.13' :: 512.97* \x*\ whence x = 371.2 Needle 4. 540.4 s ; 389.5* : : 512.92* : x* ; whence x = 369.7 Needle 5. 739.5* : 534.8* :: 512.92* : a?*; whence x = 371.0 Needle 6. 631.5* ; 458.2* ; : 512.92* : x* ; whence x = 372.2 Mean . 371.0 24 Captain Sabine's Experiments on the Proceeding in this manner, with the times of vibration as given in page 481 of " Pendulum and other experiments," the arcs always between 30° to 10°, and the temperatures as seve* rally noticed, the following results are obtained : Madeira, January 12, 1822. In a garden near Funchal, Th. 63° : Needle 3 . . , 440".8 Needle 4 . . . 441".0 Mean . 440".9 Teneriffe, January 17, 1822. On the sea-beach, near the foot of the hills east of Santa Cruz, Th. 67°: Needle 4 . . . 434".8 Needle 5 ... 435".6 Needle 6 . . . 436".6 Mean 435".7 Port Praya, Cape Verc cocoa-trees, near the wateri Needle 4 Needle 5 I Islands, January tig-place, Th. 73°: Mean 26, 1822. In a grove of 387".3 . 384".7 386".0 Bathurst, River Gambia town, Th. 76° : Needle 4 Needle 5 , February 4, 1822. • • • • • In a field north of the 379".3 . 379".3 Mean ♦ 379".3 Sierra Leone, March 20, Needle 3 Needle 4 Needle 5 Needle 6 1 822. At the foot of Tower Hill, Th. 80° : 371".2 . 369".7 371".0 . 372".2 Mean . 371".0 Island of St. Thomas, Man-of-War Bay, May 20, 1822, Th. 84°: Needle 3 . . . 363".3 Needle 4 . . . 364".7 Needle 5 . . . 367".8 Needle 6 ... 365".l Mean . 365".2 Island of Ascension, July 7, 1822. In the Barrack Square, Th. 84° : Needle 4 367".5 Needle 5 . . 370".8 Mean . 369",1 Force of the Earth's Magnetism* 25 Bahia, July 26, 1822. Needle 3 Needle 4. Needle 5 Needle 6 Maranham, August 28 the town, Th. 80° : Needle 4 Needle 5 Needle 6 In the suburb of Vittoiia, Th. 74° : 370".8 . 371".7 373".0 . 373".5 Mean . 372".2 , 1822. In a garden two miles distant from 368".9 . 363".6 363".9 Mean 365".5 Trinidad, September 28, 1822. In the Governor's garden at St. Ann's, Th. 86° : Needle 3 • • . 363". 7 Needle 4 • • . 367".2 Needle 5 • » . 363".8 Needle 6 Mean .» . 364".6 364".8 Jamaica, October 28. On the sea-beach at Port Henderson, Th. 80°: Needle 3 • • • 354".4 Needle 4 • • . 355".2 Needle 5 • • « 355".9 Needle 6 . ' • . 358".2 Mean a 355".9 Island of Grand Cay mi in, November 11, 1822, Th. 84°: Needle 3 • • • 358".2 Needle 6 Mean • • • 361 ".3 359".7 Havanna, Nov. 25, 1822. In the country south of the city, Th. 80°: ! Needle 3 • • 365".9 Needle 4 . • . 364".8 Needle 6 • • . 365".0 Mean . 365".2 New York, December 27, 1822. In the grounds of the Lunatic Asylum, Th. 30°: Needle 3 • . a 487". 7 Needle 4 , • . 488". 1 Needle 5 • • . 492". 1 Needle 6 • • . 490". 3 Mean 489". 5 26 Captain Sabine's Experiments on the Hammerfest, June 16, 1823. On the sea-beach at Fugleness, Th. 42° : Needle 3 . - . . 614". 2 Needle 4 . . . 609". 2 Needle 5 . • . . 605". 2 Needle 6 . . . 613". 6 Mean . 610". 5 Spitzbergen, July 17, 1823. On the Inner Norway Island, Th. 36°: Needle 3 . . . 723". 9 Needle 4 . . . 722". 6 Needle 5 . . . 718". 7 Needle 6 . . . . 715". 5 Mean . 720". 2 Greenland, August 21, 1823. On the Pendulum Islands, Th. 38° : Needle 3 . . . 691". 2 Needle 4 . . . 690". 3 Needle 6 . ; . 687". 7 Mean .* 689". 7 Drontheim, October 21, 1823. On the ascent of the Steinberget Hill, Th. 47°: Needle 3 569". 4 Needle 4 . . ' 577". 3 Needle 6 . . ' . 570". 7 Mean . 5 72". 5 These are the times of horizontal vibration, the squares of which express the proportion which that part of the magnetic force bears at each station, which gives the compass-needle its direction in regard to the geographical meridian. To obtain from thence the total magnetic intensity, if T' be the time of horizontal vibration, D the dip, and T" the time of corre- sponding vibration in the direction of the dipping needle ; T" s= /V 8 cos. D : and T" 2 will express the ratio of the total magnetic force at each station. London . ii T' = 513.0 D = 70.00 ii T" = 300.0 Madeira 440.9 61.50 303.0 Teneriffe 435.7 59.46.8 309.1 Port Praya . 386.0 45.26.3 323.3 Bathurst . 379.3 40.23.1 331.0 Sierra Leone 371.0 31.02.5 343.4 St. Thomas . 365.2 00.06 365.2 Ascension "369.1 05.10 368.4 Force of the Earth's Magnetism* 27 Bahia ii 372.2 04.12 // 371.7 Maranhara . 365.5 23.06.2 350.5 Trinidad 364.8 39.02.5 321.5 Jamaica . 355.9 46.55.3 294.1 Grand Cayman 359.7 48.48.3 291.9 Havanna 365.2 51.55.2 286.8 New York 489.5 73.07 263.8 Hammerfest 610.5 77.13.3 287.1 Spitzbergen . 720.2 81.10.5 282.1 Greenland » 689.7 80.12 284.5 Drontheim . 572.5 74.42 294.1 The dips which I have employed are those which I observed myself, except at Madeira, where an accident prevented my using the needle on which I could place most reliance ; and I have reason to think that the needle I did use made the dip a few minutes too great ; I have therefore taken it at 20' less. There are two other series of observations on the magnetic intensity of principal note : one made by M. de Humboldt, consisting chiefly of observations during his celebrated voyage to the equinoctial parts of the American continent, at the close of the last and beginning of the present century, twenty- four years before mine ; the other made by M. Hansteen, and gentlemen who have used instruments prepared by him, in the northern parts of the old continent. These latter are either cotemporaneous or subsequent to mine. M. de Humboldt's series includes two stations, at which I have also observed, and which are contained in the preceding list. M. Hansteen's series also includes two of the stations visited by me. It is desirable to examine how far the obser- vations correspond. In order to do this, we must first have an accurate comparison of the magnetic intensity at the stations which have served as bases to the respective series. M. de Humboldt's observations were made relatively to the intensity at Paris ; M. Hansteen's, to that at Christiana; and mine, to that at London. In the Philosophical Transactions for 1828, I have given an account of the comparison of the intensities at London and Paris, effected by means of six needles frequently interchanged between the stations ; and the intensity at Chris- tiana and London has since been compared by M. Hansteen 28 Captain Sabine's Experiments on the and myself, by a similar process. The six needles employed between London and Paris made the ratio of the horizontal force at Paris to unity in London as follows : — 1.0722 1.0675 1.0731 1.0726 1.0709 1.0717 Whence the needle, which has served as a general term of comparison for the different stations, and is supposed to make its time of vibration in London in the direction of the dipping- needle 300", would have its corresponding time of vibration at Paris as follows : — it Horizontal Vibration. 2. In the direction of the dipping-needle. 495". 2 302". 1 494". 3 302". 8 493". 302". 493". 1 302". 1 493". 5 302". 3 493". 3 302". 2 493". 4 302". 2 The dip in London, in the spring of 1827, (the period at which the comparison was made,) is considered to have been 69° 49'; and in Paris, 67° 58'. The stations, common to M. de Humboldt's series and mine, are TenerifFe and Trinidad; (in the latter case his observations were made at Cumana, in lat. 10° 27' N., and long. 64° 16' W. ; and mine at Port Spain, in Trinidad, in 10° 39' N., and long. 61° 35' W.) M. de Humboldt did not employ horizontal needles, but observed the number of vibrations which a dipping- needle, freely suspended in the magnetic direction, made in ten minutes at each station. This number was in Paris 245 ; at TenerifFe 238 ; and at Cumana 229. If, then, we suppose the relative intensity at Paris, London, TenerifFe, and Trinidad, to have been the same in 1822, as it was twenty-four years antece- dently, (which supposition is probably not strictly correct, but sufficiently so for the present comparison), the needle which makes its time of vibration in London 300", and in Paris 302".2, would make, according to M. de Humboldt, the corresponding Force of the Earth's Magnetism, 29 time at TeneriffeV 302,2 * 245 ' = 31 I'M ; and at Cu- /302 8 .2x245 f QOQ//Q mana A / a 3£o\3. V 229* We have thus, — At London 300 Paris 302.2 Teneriffe, 1799 . . . .31 111.11 Teneriffe, 1822 . . . . 309.1 J Cumana, 1799 .... 323.3) Trinidad, 1822 . . . 321.5 J The intensity at Christiana and London was compared by means of two of the same needles that were used between Paris and London, Nos. iv. and viii. They were vibrated at Chris- tiana by Mr. Hansteen, in January, 1828 ; in London, by myself, in March ; in Christiana, a second time, in May ; and in London, a second time, in June. Their times of vibration, reduced to a mean temperature (49°), were as follows : — Needle iv. Needle viii. Christiana, Jan. 10 . Noon . 1097". 25 Noon . 886". 86 London, March 23 . 1p.m. . 1049". 26 Noon . 850'. 96 ^, . .. ,, _ . Mean a.m.) , nnnl , ,, Mean a.m.) „ m Christiana, May 1-4 . > 1099". 11 . > 890". 67 and p.M.j and p.m. J London, June3 . . 1p.m. . 1053". 80 2 p.m. . 853".7 Whence, by interpolation, we obtain the time of vibration in Christiana, in March, corresponding to the observations in London at that period ; and in London, in May, corresponding to the observations in May, at Christiana. N dl 4 I Marcn23 • Christiana . 1098". 45 London . 1049". 26 \May2 . . Christiana . 1099".ll London . 1051". 76 N dl 8 | March23 • Christiana . 889". 3 London . 850". 96 \May 2 . . Christiana . 890". 67 London . 852". 46 And if we take the horizontal intensity in London as unity, in Christiana it will be as follows : — -r, ,, f Comparison in March By needle 4-^ ~ r . . _, ' [ Comparison in May _, .. n ( Comparison in Mar< By needle 8^ r . ,, J (Comparison m May . 0.9124 . 0.9157 Comparison in March . . 0.9157 . 0.9160 Mean . . . 0.9147 30 Captain Sabine's Experiments on the The dip in the spring of 1828, at Christiana, was observed by M. Hansteen to be 72° 16'.2 ; in London, at the same pe- riod, it was 69° 47': whence the total magnetic intensity at n . ... . 0.9147 x Cos. 69° 47' , n ™ .-* .' . Christiana, is as = l.Oo/o, to unity in Cos. 72° 16'.2 ' ' London ; and the needle which makes the time of vibration 300" in London, would require 294".47 in Christiana. The two stations common to M. Hansteen's observations and mine, are Drontheim and Hammerfest. At Drontheim, in 1825, M. Hansteen found that his horizontal needle, which at Chris- tiana made 300 vibrations in 816", required 866 // .77 for the same number ; he also observed the dip in that year at Christiana 72° 26'; and in Drontheim, 74° 42'. The num- bers 816", and 866". 77, reduced to the direction of the dipping-needle, became 448". 30, and 445".30 ; and the rate of vibration at Drontheim corresponding to 300" in London, is 3 Q0 '^^f/ 3 ° = 292".5. In 1827, Professor Keilhau made 448 2 .30 a second comparison between Drontheim and Christiana, with a horizontal needle which had been compared at Christiana with M. Hansteen's. M. Keilhau made the relative times 816", and 869".7, which reduced to the direction of the dipping-needle, are 448".30 and 446".8 ; and the rate of vibration at Drontheim, relatively to 300" in London, is 293.5. We have thus— Sabine, in 1823 . . . 294'M Hansteen, in 1825 . . . 292". 5 Keilhau, in 1827 . . . 293". 5 At Hammerfest, in 1827, Professor Keilhau observed 937".4 corresponding to 816" at Christiana. These make the relative times in the magnetic direction, (the dip at Hammerfest being 77° 13', page 27) 448".30 and 440".94 ; and the rate of vibra- tion at Hammerfest, corresponding to 294".47 in Christiana or 300" in London, 289".6. A previous observation at Ham- merfest is recorded by M. Hansteen (Astr. Nach. No. 146) to have been made, in 1825, by some gentlemen who had under- taken the charge of one of M. Hansteen's needles in a voyage from Norway to Archangel, and who found the time of hori- zontal vibration 930".8, relatively to 816" at Christiana. This Force of the Earth's Magnetism. 31 observation would make the time of vibration of the general comparing needle 287".6 at Hammerfest. We have thus — In 1825, as above . . . 287". 6 In 1827, M. Keilhau . . . 289". 6 In 1823, Capt. Sabine . . 287". 1 These results approximate perhaps as nearly as can be ex- pected in the high latitudes, where the small, secular, and (probably) diurnal variations in the dip, occasion much greater alterations in the horizontal intensity than take place in the lower latitudes. A remarkable Phenomenon of Sound, and of the conveyance of minutely divided Matter, during the Eruption of Mount Souffre in 1812. From many observations, I have found that thunder can rarely be heard at a greater distance than twenty miles. I have also had occasion to notice, that the eight o'clock gun of George- town, in Demerara, is often heard at Cape Batave on the west coast of Essequibo, a distance of about forty miles. The distances, however, were almost incredible to which the con- clusive motions arising from the tremendous explosions which occurred during the eruption of Mount SoufFre were propa- gated through the atmosphere. These eruptions were heard at the distance of 600 or 700 miles, namely as far as Cayenne, at Varinas, and, it is said, at Santa Fe. The whole of the coast, and most of the West India islands, were alarmed by loud reports seemingly of great guns, which were universally supposed to be caused by a sea engagement ; and the ships of war among the islands and on the coast of Guiana sailed out to reconnoitre, as they supposed, an enemy, who, however, was nowhere to be found. These reports were very loud at Pomeroon, where I heard them like the firing of cannon, incessantly for nearly two hours. They excited so much consternation in the town, from the idea of an engagement on land, as to put the troops in motion. That sound should be conveyed, or, in other words, that a 32 Remarkable Phenomenon of Sound vibrating motion of the air should have been propagated to such a distance as we find in the case before us, exceeds, I believe, every instance of the kind, and has not a parallel in history. Soon after these occurrences, we received information from Barbadoes, that the whole of that island had been visited, on the 1st of May, not merely by a nocturnal darkness, but by a complete and total darkness, which continued from about the hour of eight, a.m., till twelve at noon, and was attended by a continued shower or fall of fine sand, which completely covered the surface of the island. This wonderful pheno- menon, as might well be expected, excited the astonishment of all, and threw the inhabitants into the utmost consternation. The cause being unknown, they considered it an express visi- tation or warning from the Deity. It was also stated, but in a vague and indefinite manner, that, in the night preceding the phenomenon, some reports were heard like cannon, and flashes of lightning were seen. The next arrival brought intelligence that, at two or three o'clock in the morning of the 1st of May, the mountain SoufFre, in the island of St. Vincents, had burst forth with the most tremendous explosion, surpassing that of the heaviest artillery, throwing up immense volumes of thick dense smoke, and livid flames, ejecting red-hot rocks of enormous weight to a prodigious elevation in the air, while rivers, as it were, of ignited minerals rolled down the sides of the mountain. The whole surface of the island had been covered with volcanic ashes, sand, and vitrified earths, the more ponderous sub- stances naturally falling more adjacent to the mountain. Pro- visions and all vegetation had been destroyed, and the inha- bitants reduced to a state of starvation. The cinders were, on this occasion, thrown around to vast distances. I have a sample which was taken on the 13th from the deck of a vessel 150 miles to the windward of Bar- badoes. This may seem incredible ; but it is well known that the same phenomenon was witnessed on board many other vessels. History furnishes only an instance of the cinders of Mount Etna having been thrown upon the African coast. It must have been owing to a continuous and inconceivable during the Eruption of Mount Souffre. 33 explosive force of the volcano, or to shocks repeated in quick succession, so as completely to overcome the pressure of the atmosphere, to project its volume of cinders and heated vapours to the higher regions thereof, and to cause their reverberating around, that the sound and ashes could be con- veyed to such incredible distances. I have recently observed a notice*, which is interesting, but requires to be reconsidered, as the phenomenon alluded to is undoubtedly referred to a wrong cause. It is brief, and I here transcribe it. " Distance to which minutely divided matter may be carried by wind. — On the morning of the 19th of January last, Mr. Forbes, on board the Clyde East Indiaman, bound to London, in lat. 10° 40' N., and long. 27° 41' W., and about 600 miles from the coast of Africa, was surprised to find the sails covered with a brownish sand, the particles of which, being examined by a microscope, appeared extremely minute. At two, p.m., the same day, some of the sails being unbent, clouds of dust escaped from them on their flapping against the masts. During the night, the wind had blown fresh N.E. by E., and the nearest land to windward was that of the African coast lying between Cape de Verd and the river Gambia. May hot the seeds of many plants, found in remote and newly-formed islands, have been thus conveyed ?" It would be surprising, indeed, were it ascertained that this sand had been conveyed from the coast of Africa by the com- mon course of the wind. The supposition, however, is too absurd to be admitted. It was undoubtedly volcanic sand from some eruptions in the region of the Cape de Verd Islands, the more southerly of which, as St. Jago and Fogo or Fuego, bore N.E. from the ship, the distance being about 300 miles instead of 600. If inquiry were made, it would probably be found that some awful explosion had occurred at the volcanic island of Fogo or its vicinity on the night of the 18th of January. I should suppose this might be ascertained by inquiry of the masters of such vessels as were then lying * In the New Monthly Magazine, for February, 1827. JULY — SEPT., 1829. D 34 Dr. Mac Culloch on at St. Jago or at Brava, which is contiguous to Fogo, and frequented for its wines — the same I presume as are called Cape wines, although said to come from the Cape of Good Hope. John Hancock. On Classifications of Rocks. — By J. Mac Culloch, M.D., F.R.S., &c. In every branch of natural history it has been a principal object to adopt such arrangements of the bodies of which it treats, as should facilitate their study. The most purely arti- ficial classification may thus be useful ; but the naturalist of higher views attempts to discover the order which Nature her- self has instituted^ and thus, if possible, to combine, with utility, the history of those analogies which form the basis of all science. Such is the wide and various range of geology, and so im- portant are the great relations and analogies which it involves, compared to those which regard only its minuter details, that it has been the object of almost all the cultivators of this science to found, at least, the chief features of its classification on certain leading relations. As the essential circumstances involved in this question do not admit of being examined in this paper, the reader must be supposed to understand the following statements, without entering into much minuteness of detail. Though presenting to the eye infinite varieties of aspect, the real and definable differences of rocks are very limited. Hence, no great number of names has been required for dis- tinguishing them. It is also found, that in a single mass or stratum of one rock, bearing one fixed and steady relation to its associates in nature, the aspect, the proportions, the mode of mixture, and the nature of the ingredients, are subject to variations ; and hence a still narrower limitation of the num- ber of names, which a superficial consideration might have been inclined to apply to them, has been found necessary. Classifications of Rocks. 35 Thus/ the different varieties of granite, of gneiss, of micaceous schist, or of other rocks, have been approximated under cer- tain leading mineral characteristics, so as to found mineralo- gical families ; each of which, however various its members, is distinguished by one general title. The term genus has, by some, been applied to these associations $ and that of species, by others ; but with no great propriety, as they are not amenable to the rules which regulate the forms and differences of organized beings, to which alone it is possible to apply these distinctions usefully. On such a basis may be formed a mineralogical arrangement, or classification of rocks 5 and on it, arrangements of this nature have actually been attempted. Now, it is further found that, in nature, there are certain rocks, or families, which possess either a constant or a pre- vailing position ; or that, where many occur together, some one is always the lowest, and some other the highest. If this arrangement were as perfect as it has been imagined, there would be a fixed numerical order of succession ; or every rock might be indicated as well by a number as by a name. It is now well known that this is not the fact ; though there is a prevailing order, which may be rendered of use in geological science. It is also found that there are certain prevailing associations among rocks, or families, in nature 5 and that, in each of these, whatever differences may occur in different places, there are some general rules to which we can always safely refer. Lastly, it is also observed, that, of these different rocks, there are some which are always distinguished by their stratified disposition, while others are as invariably found in shapeless and irregular masses. Such facts present a basis for a geological classification of rocks, or for one which, com- paratively disregarding their mineral characters, attempts to arrange them as integrant parts of the structure of the earth, or of the great system of nature. It must now be observed, that certain mineral characters prevail, to the exclusion, more or less complete, of others, in each of those families of rock which are thus distinguished by their geological positions and relations. If these characters, in rocks, were steady and perfect, a mineralogical arrangement might itself be rendered perfect for geological purposes 5 if the D 2 3G Dr. Mac Culloch on association of such mineral characters with certain geological relations were constant, a geological arrangement would serve all the purposes of a mineralogical classification, or the latter would equally perform the functions of both ; but to render the arrangement absolute and unexceptionable, the geological order of nature should itself be also constant. The mineralogical method of classifying rocks is, however, not only imperfect, even in its own internal mechanism, but is at perpetual variance with the geological one, as I have fully shown in that work which treats of the Classification and De- scription of Rocks. It is therefore not only useless, even for its own declared objects, but is pernicious when adopted for geo- logical purposes ; for which cause it was there rejected. But as I have there also shown that a constant general peculiarity of mineral character is attached to each of the geological divisions of rocks, a geological arrangement, imper- fect as it is, and as it probably ever will be, is not only as valuable as a mineral one for the mere distinction of rock specimens, but, in some cases, preferable \ while it is decidedly superior as it relates to the investigation and study of nature. The very basis of the study of geology is the knowledge of rocks ; but that knowledge is of little value for any other pur- poses but the study of geology. The mere mineralogist may be permitted to adopt a mineralogical arrangement ; he ought indeed to do so ; because, to him, rocks are but the reposito- ries of minerals. The classifications which I am about to describe have either been intended for the purpose of facilitating the study of geology, or they have been considered as a branch of the science, a declaration of the order and arrangements of nature. Thus, they may be imagined to be either artificial or natural. A principle of arrangement, some kind of logic, good or bad, seems to be an inherent propensity in the human mind ; but, while the sound reasoner adapts his logic to nature, the pro- position is more commonly reversed, and nature is tortured into forms, against which she rebels. But as it is one of the qualities of a system to assimilate every thing to itself, an artificial arrangement soon comes to be considered as a natural one ; and when even its inventor learns to see only through Classifications of Rocks. 37 the false medium which he has constructed, it is not wonderful if those who follow him cease to inquire, and receive as proved, that which is mere matter of hypothesis. I hope to show that the classification of rocks which have been esteemed natural, are, on the contrary, artificial. They must not, therefore, be allowed to enter as constituents into the science of geology ; and the only inquiry will be, how far they are useful in facili- tating its study. An imperfect and ill-founded observation of Lehman gave rise to the first notion of separating rocks into two classes. That observation, as far as his researches and information extended, appeared to have for its basis a real order of things ; but, while the general principle has been preserved, the in- crease of observations has accumulated so many exceptionable facts, as to render it impossible any longer to reconcile to it the state of our knowledge or the order of nature. It was con- ceived that rocks could be easily distinguished into primary and secondary ; the first being chiefly characterized by high, and the last by low angles of elevation ; or, as more decidedly stated, rocks were distinguished by their vertical and by their horizontal positions. Hence the primitive and secondary classes were established. Other geologists, improving on this system, have pointed out the place where these two classes meet, or have attempted to assign their common boundary ; and thus the arrangement into two classes has been made more useful, if not more natural. But as this distinction has been found to be attended with some difficulty, a still more minute division has been attempted, and rocks have been arranged in three classes ; a division to which the name Transition has been applied as an adjective term, having been introduced between the primitive and secondary. This arrangement, promulgated by Werner, has been adopted by many persons, and has been esteemed strictly natural. This classification also has been connected with a system of cosmogony, even more decidedly than that which we must attribute to Lehman ; but it is not worth an inquiry which of the two was the origin of the other, whether the cosmogony or the classification preceded. It will pre- sently appear that it is not only as defective as the more simple 39 Dr. Mac Culloch on arrangement, but that it is not founded, as far as any evidence yet goes, on the real order of nature, while it is of far less utility even as an artificial arrangement. To examine, in the first place, the simple classification, or that into primitive and secondary. The primitive rocks are distinguished by the following cir- cumstances. Whatever geographical places they may occupy in nature, they are the lowest in geological position ; or else those rocks which steadily maintain the lowest places in the order of relative superposition, up to a certain point, are con- sidered as primitive. It is further stated, as characteristic of this class, that the strata are always elevated at high angles, and that they follow in consecutive parallel order. It is also said that their nature or texture is chemical, or that they bear no marks of mechanical origin ; and, lastly, that they do not contain organic remains. This class, thus determined, is found to comprise a certain number of rocks, of which the mineral characters are, to a great degree, peculiar and suffi- ciently constant ; and thus also, reversely, these mineral com- pounds are considered, wherever they may be found, as pri- mitive rocks. The secondary class is, of course, the receptacle of all those not included in the other. It is supposed that these are cha- racterized by prevailing low angles of elevation, by the general, or frequent, or necessary mechanical nature of their texture or nature, and by their containing organic remains. It is also supposed that their order is parallel and consecutive among each other, but that this order is not parallel to that of the substances in the primitive class. Hence, therefore, the boun- dary between the two is placed at that point where the change of order takes place ; or the reverse position of approximate strata indicates that the lowest of these is the last, or upper- most, of the primitive, and that the other is the first, or lower- most, of the secondary class. If, in certain cases, it happens that this reverse position does not exist, then the boundary is determined by the mineral characters of the approximate rocks ; it being observed that a conglomerate or sandstone is the lowest rock, whenever the series of the secondary strata is complete. If, again, even that rock should be absent, then Classifications of Rocks. 39 another stratum which, from previous observations, is known to lie above the conglomerate, is assumed at that point as the lowest of the secondary class. Such is a view of the arrange- ment into primitive and secondary ; giving it all the advantages that have been derived from observations far more recent thnn those of its original inventors. The limitation to its truth and utility will be examined when the nature of Werner's attempted improvement on it has been stated. In this arrangement the division is threefold, or into primi- tive, transition, and floetz ; the last being a term for which secondary may be substituted. The transition class, which alone requires notice here, is supposed to be distinguished from the primitive by its containing rocks, of which the nature or texture is partly mechanical and partly chemical ; and further, by the organic remains which are found in its mem- bers. Hypothetically, it is also distinguished by a presumed difference in origin ; a matter which cannot be examined here for want of space, and which must be referred to an examina- tion of geological theories, and to some possible future op- portunity. Thus this class is, as the name expresses, a collection of rocks, not only formed at a period intermediate between the formation of the primitive and the secondary, but necessarily occupying an intermediate place. It is proper to examine how far this subdivision is either natural or useful, as it involves a set of objections distinct from those which apply alike to both the systems. It is not natural, for the following reasons. In the primi- tive class, even of Werner, many rocks, such as micaceous schist and quartz rock, sometimes contain fragments, and are therefore partly of mechanical origin. Conglomerates also occur in this class, as among the limestones and serpentines ; and it cannot here be necessary to adduce examples of these facts. If required, the reader may consult the Classification of Rocks for them. In the transition class, again, limestones and greenstones, or basalts, of a purely chemical nature, are frequent ; and hence the distinction attempted to be founded on these circumstances has no existence. Organic remains are not necessarily found in the transition rocks, and thus far 40 Dr. Mac Culloch on that character is defective. I have shown further, that these have heen found under gneiss ; whence, according to the ar- rangement, that gneiss ought to be a transition rock ; and thus every rock found above any one that is discovered to possess such an organized body, must necessarily fall into the same class. The consequences are here sufficiently obvious ; and it is equally plain that there are no characters, either singly taken or combined, by which transition rocks can be distin- guished from the primitive. Neither is there any boundary by which the transition class can be separated from the first. None has been assigned ; and it is evident, from the last re- mark, that whatever boundary may be assumed, it must be removed as often as any organic substances, or even any imbedded fragment of a rock, shall be found in a position, or in a rock, inferior to that which has last been fixed on as its lowest member. Lastly, the transition rocks are frequently absent altogether ; a fact which, when the primitive and secondary are present, implies a contradiction in terms. This class, therefore, as a natural division, has every possible defect ; as it is not always present, does not form a transition, has no permanent or certain characters, and has no assignable boundary. Such at least is the judgment which must be pronounced upon it, as far as our knowledge of the early rocks yet goes. It is not impossible, as I formerly suggested, that there may be a division of rocks intermediate between the primary and secondary, and it is possible that its characters and boundaries are assignable. It is even possible that some of those which have been named as transition rocks, may belong to such a division ; but it is very certain that, at present, we have no definite notions of it, and cannot pronounce even on its exist- ence, much less on its characters and boundaries. As an artificial arrangement, it serves no useful purpose, as it does not facilitate the examination or classification of rocks. On the contrary, it is pernicious, as it leads to a vicious kind of reasoning in a circle ; certain rocks being first called by the name of transition, and then used to determine the class. To a certain extent, it is true, the same incorrect mode of reasoning may be applied to the primitive and secondary Classifications of Rocks. 41 classes, whenever the mere character of a specimen is used to determine either ; but, in this case, we can always prevent any error by having recourse to their actual positions in the great series of rocks, which are, comparatively, of a very de- cided nature. I have thus examined the objections to this class, taking it only on the general broad view which has been given of it. But it would not be doing the geological student that justice which he is entitled to claim from a writer who undertakes to tell him the truth as far as it can be discovered, if I did not state them more particularly. Its ingredients, or members, the reader may perceive, have never been named or defined, so that it answers any temporary purpose that may be wished ; adopting or renouncing at pleasure, and thus, like other visionary things, remaining unassailable. That which is no where is nothing ; the place of that which may be any where can never be known. If, with some writers, it comprises the later schists and limestones of the primary class which contain shells, it is still undistinguishable, even in this arrangement ; since, according to a celebrated writer on the Pyrenees, the transition rocks there alternate with micaceous schist, which is admitted to be primary. But it is easy to show that it involves both the primary and the secondary classes, that the only easily assign- able rocks in it belong to the latter, and that it has probably arisen from an entire misconception respecting these. It would be easy to show, had I here space for that purpose, that the inventor of this system had mistaken the upper red sand- stone for the lower ; and hence certain strata inferior to that, but still in the secondary division, became members of his transition class. Proceeding then to assume a wrong crite- rion, namely, the presence of organic remains and of frag- ments, one or both, some members of the primary class pos- sessing these characters, also fell into it. The effect of this invention, in the details, has therefore been to confound and intermix the two chief classes, in addition to all the objections already stated. It is easy to comprehend the inextricable confusion which it has introduced into geological writings ; a confusion indeed so great, as to render nearly unintelligible 42 Dr. Mac Culloch on many works otherwise valuable ; since nothing but minute and careful details of the connexions of the rocks described in them, can enable us to translate them into a meaning. Among the works of those who use names instead of descrip- tions, it would be quite fruitless to seek for one ; and it is per- haps the safest practice to avoid those in which the term transition occupies this prominent place. I may now venture to examine the objections which apply to the ancient division into primitive and secondary, as well as those which may be made to that method of arrangement, under certain modifications. It will be seen that the latter is free from some of those which apply to the former. I need not dwell on the objections that first meet the view in the ancient arrangement, namely, the confounding of granite and trap with the stratified rocks. With respect to the stratified, it is by no means true that, in the primitive class, they are necessarily placed at high angles. On the contrary, they are found at every angle, even down to the horizontal, though it may be admitted that angles exceeding 15° are more common than small ones. In the same way, so far are the secondary rocks from being necessarily horizontal, or placed at low angles, that they present the utmost variety in this respect. The first member of this class, the red sandstone, is frequently elevated to very high angles ; the coal strata are noted for their irregu- larity, and even chalk has been found in a vertical position. It is further supposed, in this ancient division into primitive and secondary, that a consecutive order, or common paral- lelism, exists in each class ; and that this order in the one is not consecutive to that of the other, has been more than once noticed. It is thus supposed that a general disturbance or elevation of the primitive strata took place before the deposi- tion of the secondary, and that these also were all deposited under another period of repose. Now it is very well known that, in the secondary class, there are abundant proofs of changes of position, and that there are in it breaches of the parallel consecutive order. The conclusion to be drawn from these objections is obvious. The arrangement, even into two classes, ought to be considered an artificial, not a natural one ; and those characters which Classifications of Rocks. 4& have been supposed to distinguish the secondary class are defec- tive. But, to passoverother objections, it is also deficient even as an artificial arrangement, and in points that would admit of a very easy remedy, by a slight alteration. Both classes, and the secondary more particularly, comprise rocks that ought to be separated, and which might be so without difficulty ; such as the unstratified substances, the partial deposits which have, by some, been called tertiary, the alluvial substances, and the volcanic rocks. The remedy for all these defects is easily found, by merely substituting certain modifications, which per- mit the general division into two classes to remain as it did before. In this amended classification, the term primary is substi- tuted for primitive, because it implies no theoretical conside- rations respecting the origin of rocks. The classes, otherwise, remain the same, except that they are first subdivided into unstratified and stratified rocks; a distinction, of which the propriety, and even the necessity, must be apparent to those who have read the various papers and works which I have on different occasions written, and the arguments from which I cannot here occupy room in re-stating. The primary class, therefore, in this arrangement, as far as the stratified rocks are concerned, is defined as it was before. All those unstratified rocks are also placed in this class, which are found to lie beneath the whole or any one of these strata, or even merely beneath the secondary, provided they do not, in any case, also lie above any one secondary stratum. They will not be taken out of this class though they should be found intruding, in the form of veins, into the primary strata ; unless these veins are connected with secondary masses, or may be inferred to have proceeded from such ; but they would no longer appertain to it should they continuously intrude among the secondary rocks. In practice the distinction thus becomes geologically easy, whenever the two classes are found together. But if the primary class is found alone, as there is then no opportunity of such a comparison, it is necessary to be guided by the mi- neral characters of the rocks, and by such other circumstances as experience has shown to be peculiar to them. This defect, 44 Dr. Mac Culloch on such as it is, must inevitably occur, whatever arrangement may be adopted ; as it is not usual, nor even very common, for both classes to be found in contact, or at one point. The secondary class commences as in the ancient arrange- ment, where the primary ends; but as that proceeds down- wards, this extends upwards. A conglomerate and sandstone frequently, but not necessarily red, is, as already observed, its lowest possible boundary. But as this may be absurd, it is not a necessary one ; and that must then be sought in the lowest stratum or rock, which is known to be, on ordinary occasions, superior to it, and of which the mineral characters, as in the case of the primary strata, are known. No rules for the boundary of this class must be drawn from the nature of the primary rock on which its lowest member reposes ; because this may be the lowest as well as the highest of that class. Such also are the occasional deficiencies in the secondary class, that its upper members may rest on the primary, and even on the lowest of these. Thus the extremes of both classes might meet ; an instance approaching to which has been elsewhere quoted by me as occurring in Sutherland. With respect to the unstratified substances, every such rock is considered as belonging to it which is not included in the primary division. But those of this class differ in one important point from the corresponding ones in the other ; as they may, and do, send veins through the primary rocks, without forfeiting their class. It needs only be added, that their masses are generally supe- rior to the strata with which they are associated. Such was the arrangement adopted in the work on Rocks, for the purpose of describing their characters ; and as such, it was suffered to remain, in other points, irregular and incom- plete. As the rocks of the tertiary strata, for example, agreed in character with corresponding ones in the secondary class, no attempt at a third distinction was made. In the same way as jasper and some other substances occur in both classes, it was held unnecessary to repeal them in both, where one discussion would serve, so that they were placed in an appendix, as being merely accidental modifications of some members in both classes. Such an arrangement, it is evident, made no preten- sions to a classification, in the proper sense of the term. With Classifications of Rocks. 45 equal neglect of geological classification, the remaining sub- stances, comprising volcanic rocks, coal, alluvia, and other matters, were placed in another appendix, because it would have been impossible to have followed a geological order in the descriptions of these, without the greatest inconvenience. These deficiencies, however, being palpable and acknow- ledged, were of little moment ; particularly as the arrangement was not intended to form part of a system of geological science. The most serious defect was one, which, I fear, is still irremediable. It is that which relates to the overlying rocks ; a division, the very name of which is objectionable. There can be no doubt that some of the porphyries and clay- stones are truly primary ; but the difficulty was then, as it is now, to determine which were such, and to find a mode of distinguishing them from secondary ones. Thus the whole were placed in one family, and in the secondary class ; a plan which had no other merit but its convenience for the purpose of describing the several kinds with the least repetition or confusion. There are some practical defects, I must now add, in a clas- sification of rocks, -were it even a perfect one, inherent in the very nature of the subject, and consequently irremediable. One of the most obvious of these, is the repetition of the same substance in different classes: of which limestone, jasper, siliceous schist, and others, are examples. Custom has led us to treat of the limestones of. the two classes separately ; yet to attempt to do the same for the other substances would not now be tolerated ; besides which, there is perhaps not enough to be said respecting them, to justify such a division. In the same manner limestones, sandstones, and other substances, occur in the secondary class, and also in what may be called a tertiary one. The former, indeed, is even an alluvial rock, in the shape of travertino and coral sandstone ; so that it occurs in four distinct parts of the system. But I need not enumerate more of these defects and difficulties. They cannot be reme- died ; but we must recollect that they are in a great measure artificial evils, and of our own creating. They have arisen from one of those abuses of logic, which attempts to reduce every thing to one system; from a desire to carry into a 46 Dr. Mac Culloch on department of nature, where it is not applicable, that kind of arrangement which had been found successful in others. Though there is no prospect, therefore, of producing a clas- sification of rocks, either natural or artificial, which can be followed in a systematical and descriptive work, there is no reason why we should not attempt to arrange them in some order. Such a classification, could it be perfected, would still have its uses in a scientific view, as it would represent the order of nature, or at least declare the connections, analogies, or relations, of rocks, in a compendious and convenient man- ner. It would also be of use for the mere purposes of descrip- tion and arrangement; because it would be a point from which to depart or deviate, without the risk of straying too far or falling into confusion ; standing as a beacon to indicate such changes as might, from time to time, be made En it. Even if highly imperfect, it would still be useful ; because, by placing the imperfections and difficulties in an obvious light, and by showing those that actually exist, it would lay the first step towards a better system. I am very far indeed from presuming that I have discovered an unexceptionable classification ; but if no one will attempt an imperfect one, we are very little likely to succeed in finding one that shall answer the desired ends. It is also true, in every thing, that what an inventor has been unable to accom- plish, is often done in an instant by those who might never have made the original suggestion. It seems to me that something like a natural classification may be made on the basis of the materials collected for that System of Geology which I have long since prepared for the press, which has remained these many years dormant in its MS., and may possibly thus remain for ever. The reasons for distinguishing the unstratified from the stratified rocks, in both classes, must long since have been obvious. Those for divid- ing the stratified rocks of the ordinary secondary class into three, are, in my own estimation, satisfactory even as a ques- tion of geological theory ; but being here compelled to crowd what I can into the narrowest possible limits, I dare not attempt to state them. I shall only further premise respecting this classification, Classifications of Rocks. 47 which is here given in a tabular form, that it coincides so well with that which has been already used for the practical pur- poses already mentioned, as to admit of their both standing together. Very few modifications were, in fact, required to permit the same enumeration to serve for both ; and thus two modes of division have been applied to the same list. Thus, one of them represents what may hereafter be rendered a natural classification in reality, as it is, now, but an attempt at one ; while the other is an artificial one, which may safely be adopted, at least as such, subject always to future amend- ment. I have merely numbered the new classes for the pre- sent, from an aversion to introducing new terms. If geologists shall approve of this plan under the present or some modified form, it is possible they may not feel the same dislike to the Greek compounds, of which I have merely suggested the first. I know not very well, if there must be a name, what better expedient could be devised. ARTIFICIAL SYSTEM. PRIMARY CLASS. STRATIFIED. Gneiss. tMicaceous schist. Chlorite schist. Talcose schist, partial. Hornblende schist. Actinolite schist, partial. ♦Quartz rock. *Red sandstone, f Argillaceous schist, fine clay slate and graywake. Diallage rock. Serpentine, ambiguous. ♦Limestone. Compact felspar, partial. Jasper modified from * 1 „ r . Siliceous schist, modified from 1 1 W , here gramte ° r Chert, modified from $ when ar- f tra P. T P resent ' gillaceous. J P artiah UNSTRATIFIED. Granite, from the ordinary appearance to that of greenstone and basalt. C. felspar porphyry, where decidedly limited] Often to the primary strata [doubt- Clinkstone and claystone, in the same cases J ful. Serpentine, when solely connected with primary strata, or granite. NATURAL SYSTEM. CLASS 1. Protolith? &c. CLASS 2. 48 Dr. Mac Culloch on ARTIFICIAL SYSTEM. ill w < b £ 03-2 n O) u o» Cfl / ■a o o I SECONDARY CLASS. STRATIFIED. ♦Sandstone. Conglomerate and fine. Old red, of various colours and qualities. Limestone. Mountain limestone of English. Tran- sition of some. Sandstone, various. •(•Shale ) Ait . *Clay } dltt0 ' Limestone. Coal. Limestone — Magnesian, first above the coal series. ,, % Argillaceous. Lias. Muschelkalk, &c ,, Compact, various ; generally organic. „ Oolithic. Chalk. ^Sandstone— Red marl. Red sandstone, containing salt and gypsum. £ < I jo Quadersand- ui „ White, various, and sand. stein, &c. „ Green, and sand \ „ Ferruginous, and sand J t^Variou, Jasper, modified from * "j Partial, only where Siliceous schist, modified from + \ trap-rocks are Chert, modified from % \ present. Salt and gypsum considered as minerals in this class. UNSTRATJFIED. Serpentine, as connected with trap chiefly. Pitchstone, comprising pearlstone. Known in veins only. /Trap— Indurated clay ; base of the amygdaloids. Claystone. Indurated claystone ; comprising some basalts. Clinkstone. Compact felspar. Basalt ; of hornblende only. Greenstone. Syenite. Sometimes emulating granite. Augit rock. Hypersthene rock. Porphyries ; with various bases. ^ „ Amygdaloids. a 5 | E o 2 Ph ft TERTIARY CLASS. Limestone Sandstone Chert. Millstone Shale Clay Marl Uncertain successions of marine " and fresh water strata ; or all fresh water. Gypsum NATURAL SYSTEM. CLASS 3. CLASS 4. CLASS 5. CLASS 6. CLASS 7. Classifications of Rocks. 49 ARTIFICIAL SYSTEM. NATURAL SYSTEM. ALLUVIAL CLASS. Marine, elevated; loose. Italy, containing marine remains. „ „ indurated. Marl of Italy. Coral. Islands of Pacific, &c. Terrestrial, loose, of very various materials. „ general, of diluvian origin, or else elevated and marine. „ local, from transportation ; and from de- composition. ,, soil. „ solid, Travertino, of Italy. „ „ West Indian and Coral sandstones. Messina and others. „ „ Marl of lakes. »» „ Peat. class 8. CLASS 9. VOLCANIC CLASS, CLASS 10. Lava } Presenting, under these general terms, analogies to many of the trap-rocks. I know not that I have much to remark on the preceding table, which the reader who is versed in geology may not re- mark for himself. The repetitions of the same rocks in the different classes became a matter of course in a classification of this nature. I have attempted to distinguish some porphyries as ex- clusively belonging to the primary class ; as is unquestionably the fact. In the 5th class, I have given only the principal varieties of the different rocks. To form a classification on the basis of the English strata, would be to prejudge a question of which we know not as yet enough, and to commit again an error from which geology has already severely suffered. To distinguish more minutely in the secondary or tertiary classes, would be to introduce a new and insufferable arrange- ment; because the same principle must also extend to the primary, giving us three or four kinds of gneiss, of quartz rock, and so on. Important as particular strata may seem in an English or any other series, it must be remembered that they are still but varieties, in the general system. JULY— sept., 1829. E 50 Remarks on the Worari and Sirvatan. I have made no attempt to place the strata in the order of nature, for sufficient reasons. In the first class, there is no order in nature ; there is none in the coal series. In the fifth class, the order of England is an order among varieties which are excluded by the arrangement. In the seventh, the same is true. I could gladly have extended the minute commentaries on some of the names ; but that was inconsistent with the tabular form ; and as I have now exceeded the prescribed bounds of this paper, I cannot venture to add them in any manner. Remarks on the Worari and Sirvatan, Centuries have now elapsed since this dreaded weapon, which takes away life like a magic wand, without causing the slightest pang, became known to Europeans, in its effects at least. It is strange, therefore, that the subject should still remain in- volved in such profound mystery, with regard to the poison, the mavacuri plant, which affords it, and that instrument, the sirvatan or blow-pipe, through which it is propelled upon the victim. The question, what plant affords the worari poison, involves, I presume, one of the most interesting inquiries in the whole department of natural history at the present day, and deserves from us a particular and attentive investigation. Having examined the Mandavacs, Francisco and Domingo, two intelligent Indians, who were born and bred on the spot, of the tribe most famed for producing the most active worari, and who lived in the vicinity of the mountains which produce both the deadly poison and the instrument of its conveyance, I have received from them separately a most correct and satis- factory account of this affair. These Indians stated, that, both for the mavacuri and sarsa, they go up the Siapo and contiguous streams, or about the mountains of Unturan and of Achivucary, as observed by Humboldt*. * They persist that there is no sarsa in Cassiquiari nor in the Rio Negro. Remarks on the Worari and Sirvatan, 51 They could give, however, no information respecting the flowers ; but they know the plant well, and call it mavacuri ; and they state, that it is of the gourd kind, or one of the cucurbitacea, of the size of a large orange, round, and having a hard shell or pericarp, which is used at times to contain the poison. The mahwy, they say, is the plant of which they make the blow-pipe for projecting the arrow. This plant, according to their representation, has large roundish leaves, is jointed, and has slight partitions, like those of the trumpet-tree, which they punch and clear away with long sticks of hard wood, fitted for the purpose. On further conversation with Domingo, it appears to be a species of palm, as, in respect to the texture, leaf and seed, he compares the different parts to the eta and camawari. On showing him the small pigmy palm growing on the sands of Essequibo, he said it was the wahwy ; exactly in respect to the stem ; but not the leaf, as that is bifid, and that it was similarly jointed. The lining tube is of the same material, a junior or smaller plant of the same kind. In regard to the manufacture of the poison, Domingo and Francisco say, that they, in general, add nothing, though some, to thicken it, add the bark. They merely peel or scrape off the bark, and bruise it well in a mortar. The mass is then put into a funnel or cartocho made with wild plantain leaves, and having a little cotton at the bottom to strain it ; plenty of cold water is poured over it ; and they proceed in the same manner as in drawing the lixivium of ashes. This infusion is put into an earthen pot; (that which is here called a buck-pot), and boiled down to a proper consistence. This was related circumstantially by Domingo and Fran- cisco, separately. — They had no idea of the addition of other substances (ants, &c), serving, in reality, only to dilute, and render the poison less active, as prescribed by the Indians living near our settlement, all of which are but inventions like those of the charlatans of Europe to throw mystery over the affair, and enhance the value of the art. It is very surprising that men of good sense, like Mr. Waterton and Mr. Hillhouse, E 2 52 Remarks on the Worari and Sirvatan. who, as I should suppose, have had opportunities of better information, should have the credulity to notice or respect such fictions. The following extract from a letter of Mr. J. Forsyth will throw further light on the subject : — 11 I received your letter of the 30th ult. requesting a speci- men of the worari vine. I am sorry it is not at present in flower ; but I send you a small branch of it, and two other vines, called worarybally and courampoey, which the Indians use as auxiliaries to strengthen the former. You will also receive two small roots of the worari vine, which will grow if immediately planted ; it will require a great proportion of sand mixed with the earth it is planted in, as it is found growing on sand hills. " The mode of preparing the poison is as follows : — The inner bark or rind of the root (for it is the root only that is used) is scraped off into some vessel. The worarybally root undergoes the same process ; but it is the vine itself of the courampoey that is used. To these, mixed together and well boiled down with some water, the Indians add some peppers, and further boil the whole mass to a thick syrup. M This account of the process, I have had from the Indians; but they are to bring some of these roots, &c, and make the poison in my presence. I shall, therefore, have it in my power, I hope, hereafter, to give you a more accurate descrip- tion of this process." If such a thing does in reality exist in nature as a direct sedative, in the strictest sense of the term, I should imagine it to be this extraordinary vegetable extract. Its operation on the animal frame is most mysterious. It extinguishes the vital spark without a pang or a struggle, if prepared without any other substance being added, for the most efficient poison is prepared from the worari vine alone. The sensation and effect it produces are extremely analogous to those which arise from excessive bleeding ; the animal, under its influence, sink- ing from existence in the most placid swoon. On the Parima, amongst the tribes the most celebrated for the use of the worari, I was told, that salt and sugar were consi- dered as the best antidotes to this poison. The same was stated Remarks on the Worari and Sirvatan. 53 to M. de la Condamine, upon the Amazon ; but afterwards, if I remember well, it was said to have been disproved by some experiments made in Germany. I am, nevertheless, inclined to think, that some of the tribes do possess a secret antidote to the worari ; for I was assured by the Portuguese, that the Indians of the Rio Negro are in the habit of shooting birds and monkeys with the worari, and after- wards resuscitating and transporting them to Para for sale. This would be an interesting subject for a traveller to inves- tigate. Could such an antidote be found, as to render the worari manageable, I feel a persuasion that it would put us in possession of a most important medicinal agent in convulsive disorders, as in tetanus and hydrophobia, and in diseases per- haps of an acute inflammatory nature. Does it kill by the privation of oxygen, the pabulum of the blood, and supporter of vitality ? — If this were the modus operandi, by which it subverts the living power, its effects might possibly be restrained by inhaling the oxygenous gas, or by cautiously throwing oxygen into the veins. Be this as it may, it is probable that the same principle belongs to very different plants. If so, an important discovery remains to be made — that of ascertaining the proximate prin- ciple, which, acting on the nervous and vascular systems, proves so subversive of animal life. John Hancock. On a Method of Cidtivating Plants in Walls, for Ornaments ; with a Catalogue of those which succeed under this treat- ment. to the editor. Dear Sir, For these ten years past, and more, I have been intending to communicate to you, for the sake of such of your readers as it might interest, a species of improvement (if I may use this grandiloquous term for want of a better) in one department of ornamental horticulture, which I had put in practice in dif- ferent places long before this ; yet I have delayed it till I need 54 On a Method of not delay it longer. I had thought that it might possibly be known to others as well as myself; and was unwilling to pro- duce as a novelty what might not prove one ; yet, having now communicated it to numerous persons, to all of whom it was unknown, and not having seen, in this country, a single attempt of the same nature, I suppose I may venture to pre- sume that this notice will in reality present a novelty, and, slender as the fact is, a new source of ornament and amuse- ment in a department which ought to despise nothing, since its sole ends are but amusement and ornament. The bare fact itself is known to every gardener, and even to botanists \ but the application has been overlooked, or Art has neglected to profit by what Nature offers to its eyes every day. I allude to the facility with which many plants, a great range, in fact, of even highly ornamental flowers, grow in or on walls ; in many cases, even selecting them in preference, where the choice is left to themselves. And when I recall this familiar fact to horticultural readers, there are some who will, perhaps, immediately see the application here intended ; but as none seem yet to have done that, I may be allowed to point it out. In the ancient architectural gardens, masonry formed an essential ingredient ; and, in a great measure also, it was necessary, that this masonry should be displayed, because it belonged to an architectural composition. We may regret, in passing, that the rage of innovation, too often hurrying from one fault to its opposite, has swept all this away ; yet, though modern gardening has not only done this, but attempted to exclude all sight of such art, it cannot always and everywhere succeed. In many ancient establishments there are still sub- sisting remains at least of former ages, maintained through necessity or other causes, yet, in general, now producing only deformity, divested as they have been of all to which they once belonged, and, often, further associated with modern freedom, so as to produce effects scarcely less dissonant than would arise from an intermixture of modern and ancient fashions in dress. In other cases, walls are matter of necessity, for the mere purposes of defence or separation ; or perhaps the wall of the fruit and kitchen -garden, unoccupied by fruit-trees, in- Cultivating Plants in Walls. 55 trudes itself disagreeably. Sometimes, a peculiar form in the ground about the house or garden renders walls, the support of terraces or otherwise, indispensable ; and in similar places staircases of masonry are demanded for communication, while the abandonment of any architectural plan or structure in these, renders that a source of absolute deformity which was once turned towards the general good effect of the domain. Thus also may I point at the walls of hothouses, green- houses, and so forth, often interfering with the beauty of the flower-garden, with which they are so frequently associated, and very especially so, where brick, and not stone, is the material. But not to dwell further on these cases, it needs not be said that since the masonry about gardens has now abandoned all attempts at beauty, whether in the disposition, design, or exe- cution, it is in almost every instance a deformity, and often to so great an extent as to injure materially the general effect of an ornamental garden, at least where taste has been called on to preside. That indeed needs not be urged, since it is acknowledged in the attempts at concealment by means of trailing shrubs, the only remedy in use, yet not the only applicable one, and one also which, in some cases, cannot be applied ; while, fur- ther, in others, the effect which it produces is not the best that could be obtained. There are many of the cases alluded to, such as in terraces and staircases, or in very low walls, in- cisures, and narrow passages between walls, where trained shrubs are inconvenient or inapplicable. But not to enume- rate all the objections to this system, there is also a question of taste here involved. In the first place, the number of shrubs capable of being thus trained is limited, and thus we are cramped in point of variety, and not less perhaps in that important circumstance in horticulture, the succession of flowers. And these plants are also all shrubs, which, though they include more than one rose, the jessamine, clematis, honeysuckle, and other flowers of great sweetness and beauty, form still but a limited list, and a list which, in any one place or spot," will always be small, from the great space which any one plant occupies. 56 On a Method of Nor is this the only question of taste. If a whole bare wall is always an ugly object, such masonry is far from being so under partial concealment, at least if of stone. Painters know well the value of such tints and such flat vacant surfaces, in enhancing the effects of form and colour; nor is there per- haps a local and limited, a formless, or shapeless object more engaging than the grey walls of an ancient abbey, when the interstices of the stones, the broken buttresses, the soffits, corbel tables, or whatever other " coin of vantage" give root to the wild plants which find their own lodgments there ; to the ash, the ivy, the w T allflower, antirrhinum, valerian, and even the tufts of grass, which mark the ruins of past days. The painter's study of such a ruin forms, in fact, the principle or basis on which the present proposal rests ; it is to imitate nature in these dispositions, and thus to give interest and beauty to what was deformity. And if the utterly bare and naked wall of the ancient abbey or castle is deprived of more than half its beauty by that nakedness, no less than does the modern and necessary garden wall, thus bare, distress the eye of taste: so if no painter would hesitate in preferring tLe ruin thus partially ornamented with plants, to one where the whole masonry should be concealed by ivy, we may draw a similar conclusion as to that vulgar wall which is entirely concealed by trained shrubs, and that which is here proposed to ornament in a more sparing and varied manner; though, as to the cases in which the one or the other mode ought to be adopted, no rule can be given to guide what taste alone must direct for each case. Let those who may doubt, that greater beauty may often be produced in this manner, recollect, if they can, such ancient castle or abbey wall as they may chance to know, thus partially concealed, or else entirely covered with ivy; and after this, decide : and could one example of the bad effect of an universal green covering be of use, I might point out Restormel Castle, in Cornwall, as an instance, where the effect is thus totally ruined by that ivy which conceals every stone, and gives a magnificent specimen of ancient castellated archi- tecture the semblance of a huge round bush. I need not proceed further, as far as the questions of beauty and taste are concerned ; since no rules can be given for the Cultivating Plants in Walls. 57 disposition of such plants, any more than for the comparative choice of trained shrubs, or scattered flowers and plants, or a mixture of both. In all cases it is a question of pure taste, or of effect ; but it belongs to the department of the painter, rather than the gardener ; and to him especially, the careful student in foregrounds, who best can judge of the power and effect of forms and colours near to the eye, and who alone can regulate those in Nature, as they would form the principle of distribution in his own imitations of her. Fortunate, in- deed, would it be for the art of ornamental horticulture, if it were made a branch of the landscape painter's office, not of the gardener's ; nor will the flower-garden and the shrubbery ever become what they may be rendered, until this is done, or till the ornamenting gardener shall add a knowledge of landscape, through the study and practice of art, to his other qualifications. That it is not so in this country, that such is not even suspected to be the true and only road to beauty of this nature, is a proof, among a thousand others, of the almost universal ignorance of art, the almost universal absence of real taste and knowledge, which, in spite of the as universal and daily pretensions to a knowledge of pictures, pervades the opulent, and the otherwise educated, in Great Britain. But I must proceed to another branch of this subject, to matters of detail. That a very large catalogue of plants, including many very ornamental flowers, can and do grow out of the interstices of masonry, will shortly be seen in the subjoined catalogue ; limited as that is, from being almost confined to our own native plants. The fact is familiar to botanists generally, though such a catalogue has never yet been made. And while they know also that many plants prefer the surfaces or crevices of rocks to the freer soil, it will be found that these are equally willing to grow out of walls. Yet as a matter of practice, a few words are requisite on the nature, on the structure or texture of the wall in which some plants will grow more freely than others. Such remarks must be here made general, as it would have immeasurably prolonged this paper to specify them as to each plant ; a few occasional notes or remarks must serve the purpose of information as to some of the most remarkable. 58 On a Method of It might be inferred beforehand, that more plants would grow (to take extreme cases) from a wall of rude stone ma- sonry laid in clay, as is not an uncommon practice where lime is scarce, and either pointed with lime or not, or from a wall built by grouting, than from a compact and well-laid piece of brick-work. Such is the fact ; and it is also true, that many plants will grow on the surface or top of a wall, which will not root in the interstices among the plaster, from the accu- mulations of soil which so easily form in that part. But a very great number, and many of the most desirable, will grow in the interstices of even the most well-wrought wall, whether of brick or stone, and even where the cement is of the firmest quality, as I have put to the test of experience, times without number. And this is the fact, of which I have found our gardeners particularly incredulous; while I have never seen one such attempt made in this country, if I except my own. This, however, is an essential point ; and it is needful, there- fore, to bestow a few further words on it. The process may commence with the very building of the wall, by laying the roots in the mortar as the work proceeds ; roots of perennials, of course, as it is not worth while thus to labour for annuals. I need not point out all the plants which may thus be intro- duced, as gardeners will easily supply what I omit ; but I may mention, that this plan succeeds with the whole genus of Dianthus for example, and that every pink or carnation that I have ever seen tried, has thus rooted itself. And, with this tribe, the effect is peculiarly pleasing and ornamental; as their proliferous quality enables them to produce large cushions from a single root, with which a wall can almost be covered, were it deemed expedient. The same practice succeeds with the Tussilago fragrans, with the Antirrhinums, Sedums, and others ; but that which I omit may be easily conjectured, as those which I have not thus tried will also leave room for the endeavours of others. Of sowing seeds in the same manner I have less experience, having never been able to return to the only spot where I had the opportunity of fairly trying this method, yet I see no reason why it should not equally succeed. For a wall already built, it is plain that another proceeding is required. In this case, I have opened the pointing with a Cultivating Plants in Walls. 59 chisel, sufficiently wide to admit the root easily, and penetrat- ing so far as to reach the looser mortar of the interior. After this it is secured by means of fresh lime or clay, to guard against accidents until it has taken root ; nor are the roots of such plants long in finding means of penetrating the firmest and best laid pieces of masonry ; having thus succeeded in a brick wall, for example, where the cement was so stony that the bricks gave way to the chisel in preference to the lime. The power of the Tussilago fragrans, in this respect, is quite extraordinary, and even proceeds at times to more than hazard, to destruction ; since I have seen one case where such a plant had found its way from a garden, through and through the wall, in fifty places and more, sending out an off- spring at every joint, on both sides, and ultimately dislocating a stone wall of three feet in thickness, so as to be on the point of oversetting it. It is in this manner that I have most frequently sown the seeds both of annuals and perennials, and with general success ; and I need not dwell on that part of the subject, as I also need not prolong these remarks on the mode of conducting this sort of cultivation. I may only add, that in dry seasons or peculiar circumstances, it would be expedient to keep the plant moist until it is rooted ; while it will not be difficult to find expedients for this purpose by means of water and strings, or otherwise. Let me now make a few remarks on the following catalogue, as I am desirous to restrain this paper within as moderate bounds as possible. It is not solely a catalogue of our native plants, as far as they will grow in such situations, but, such as it is, I have introduced none that I have not actually seen thus growing, through the length of time in which I have paid attention to this subjeet. If it also contains every native plant that I myself have so observed, though I have no doubt that there are many more, and if I intended at first so to limit it, I could not do this ; because there were some important plants capable of such treatment, and belonging to no native genus, and which therefore could not else have been pointed out. And this plan I have followed wherever the genus was native ; that is, I have introduced, under the genus, only the 60 On a Method of native species, referring in a general manner to the foreign ones. My object in this was chiefly brevity ; as I might otherwise have transcribed a large portion of our catalogue of cultivated plants. Thus, every Sedum which is hardy, and every Diahthus which we can cultivate, will grow in this manner ; and to have quoted nominally the whole of such lists would have been tedious. A few genera, of which we have no examples, are named in a note, or alluded to as offer- ing probabilities. On the other hand, the catalogue is too long in one sense, because it includes many plants which no one would be at the trouble of cultivating. But I did not well know exactly where to stop in omitting ; while, as the fact itself is a question of botanical physiology, I thought it inexpedient to sacrifice a catalogue once made ; since that bare catalogue might, in ano- ther way, interest those who have attached themselves to our native Flora. I am not aware, finally, that I have omitted any thing necessary ; and shall be pleased, if a suggestion so simple, and no less neglected, shall add any thing to the amusement or interest of those who occupy themselves with this elegant pursuit ; shall lead to the display or production of one new beauty, or the concealment of one deformity. And if I could once have referred, for a full proof of the truth and the effects, to a flower-garden once constructed by myself at Dunkeld, I must regret that I can no longer command that ; the whole of this particular part of that garden having been destroyed to give way to some alterations. Catalogue of Plants which admit of being cultivated in and on Walls. An asterisk * marks the few which are most deserving of cultivation. Antirrhinum *, almost the whole genus — cymbalaria — elatine — repens — linaria — orontium — majus — arvense — minus Antirrhinum spurium With every other hardy one of this genus. Aiva — prsecox — flexuosa Arab is — th ali ana — stricta — turret a Cultivating Plants in Walls. 61 Anthyllis — vulneraria * Arenaria — trinervia — verna — rubra * — serpyllifolia — tenuifolia Anethum — foeniculus* Apium — petroselinum * Acrostichum — sept entrion ale * Asplenium *, the genus — geterach — trichomanes — viride — rut a muraria — adiantum nigrum — lanceolatum Adiantum — capillus Veneris * Under this letter I may name some of the genus Aly ssum , and such of the Agave and Aloe as are sufficiently hardy, having witnessed their success. The American Aloe, as it is popu- larly called, may be thus ma- naged in masonry so as to pro- duce very pleasing effects. Bromus — mollis — sterilis — diandrus Bellis — perennis* Borago — officinalis * Ballot a — nigra Betula — alba* I have seen this tree growing to the height of twenty feet and more, out of a very thin and well-laid stone wall, without any communication with the earth. Carduus — lanceolatus Cherleria — sedoides* Cotyledon — umbilicus* — luteum With probably any foreign ones sufficiently hardy. Cerastium — vulgatum — viscosum — arvense — semidecandrum Cistus — helianthemum * And I believe every cistus, na- tive, and otherwise hardy. Cardamine — hirsuta Cheiranthus *, the genus — fruticulosus — sinuatus — incanus I have known only these species, but suspect that all the genus would succeed. Cressis — tectorum Convolvulus — sepium* — arvensis * And probably every hardy Con- volvulus and Ipomea. Their creeping powers render 'them peculiarly applicable in certain cases. Chrysanthemum — leucanthemum * Cochlearia — officinalis — greenlandica In general not native. Calendula — vulgaris*, and Crassula, wherever hardy, * 62 On a Method of Dianthus *, the whole genus Geranium *, the genus — barbatus — maritimum — prolific — moschatum — armeria — lucidum — caryophyllus — rotundifolium — deltoides — robertianum — coesius i — cicutarium I have merely mentioned the I suspect it also to be true of species for which I can an- many foreign species. swer, but believe it true of all Hordium the genus, and it is particularly — murinum ornamental. Hieracium * Draba — murorum — verna — pilosella — hirta — sylvaticum — muralis Leontodon Euphorbia — taraxacum — portlandica * Lepidium And, I suspect, many more. — petraeum Echium — levigatum* — vulgare * Lactuca Erysimum — virosa* — barbaria — scariola — alliaria In foreign and hardy plants, un- der this letter, I may point Erigeron — acre * out Lavandula stsechas. Epilobium Medicago — angustifolium * — lupulina * Fumaria *, the genus Matricaria . — capreolata — parthenium* — lutea Myosotis i — officinalis — arvensis* — clariculata — versicolor * Festuca Mercurialis i — myurus — annua — duriuscula Origanum — ovina — vulgare * . — rubra Ononis — bromoides Fraxinus excelsior * Like the birch, despising soil. Fragaria — i vesca * And especially capable of being rendered very ornamental in this manner. Galium — anglicum — arvensis * I find this noted, yet without ac- curately recollecting the parti- culars ; and in foreign plants, the Oenothera mollissima, being very ornamental. Plantago — lanceolata Prenanthis — muralis* Cultivating Plants in Walk. 63 Parietaria — officinalis* Poa — rigida — compressa Phalaris — phleoides Phleum — paniculatum — nodosum Papaver * — argemone — rheas — dubium Pteris — crispa* Polypodium * — vulgare — fontanum — cristatum — rhaeticum — fragile — dryopteris Pinus — sylvestris* Growing to a considerable tree, like the birch, out of solid stone walls. Rhodiola — rosea* Rosa — spinosissima * And suspected to be true of some others. Rubus — fruticosus* — caesius * Probably more. Reseda — luteola * — lutea * Of plants not native, the Reseda odorata will also grow in this manner from seed, and pro- duce triennial plants. I believe I may add the Rosmarinus officinalis among foreign spe- cies. Sagina — procumbens — apetala Statile — armeria * Solidago — virgaurea* — cambrica* Sonchus — oleraceus Silene * — nutans — maritima — ■ armeria — acaulis Sempervivum — tectorum* And probably all that may prove hardy. Sedum * — album — acre — . sexangulum — anglicum — dasyphyllum — reflexum — rupestre And doubtless every hardy spe- cies in this genus. Many of them are very ornamental. Sysimbrium — tenuifolium — murale — sophia — iris * Senecio — vulgaris — squalidus — viscosa Salvia — verbenaca * Saxifreaga * — tridactylitis — hypnoides 64 On a Method of I have lost the note belonging to this genus, and will not con- jecture now ; but I believe many more, and especially the Alpine ones, will thus suc- ceed ; among others, the beau- tiful oppositifolia. Teucrium — scorodonia * — chamaedrys * Tamarix — gallic a Thalictrum — majus* — alpinum * Thymus * — acinos — serpyllum — nepeta The serpyllum forms a singularly beautiful ornament. I have already noticed the Tus- silago fragrans, and may add that few flowers deserve culti- vation better, from the singu- lar fragrance of that which flowers when there is scarcely another appearing. This plant ought to be added to our Flora ; growing in Guernsey in so many and such places, that it cannot have escaped from gardens, the more espe- cially as it is there cultivated but in very few, and also but recently. Dr. Smith, indeed, while admitting those which he knew, says that, the Flora of these islands has no more claim on a place in a British one than the Flora of Gibral- tar ; a somewhat singular com- parison, it must be admitted, for a Briton, acquainted of course with the history of England, and of that country which was not the conquest, but the conquering side. Veronica — arvensis * — verna * Probably more. Valeriana — rubra* — calcitrapa — locusta Verbascum * — thapsus — lychnitis — pulverulentum — nigrum Vicia — sylvatica* Urtica — diocea — pilulifera Among foreign genera, the hardy Yuccas. Such is the list of my experience, having been unwilling to go beyond that ; but I may suggest one or two points for the consideration of those who may be inclined thus to amuse themselves. I presume that almost every hardy Alpine which prefers rocks, such as some alyssums and saxifrages, would thus succeed. It is probable that similar success would attend such of the foreign plants as grow in dry sands ; the mesem- bryanthemums, for example, should there be any hardy ones discovered, and that it would be true in general of all the succulent plants, which nature has contrived for these very Cultivating Plants in Walls. 65 ends. Lastly, an attention to the genera here named will in- dicate experiments on other species, or, as an example, if the Lychnis viscaria will thus thrive, so might the Chalcedonica. Modern botanists may be shocked at some of the antiquated names here adopted ; but the remarks were associated with names acquired before it became the essence of " the lovely science" to change its nomenclature once a year ; and I saw no great necessity for consulting a table of synonimes which might be changed again before this paper was printed. A science of names cannot suffer much by such neglect, as long as there are catalogues ; and it is probable that the majority of readers will still find themselves most at their ease in the fashion which is passed away among those who undertake to regulate the fashion of botany. With your permission I will now add a postscript on a subject of an analogous nature, interesting for the same or similar reasons, yet to a somewhat different set of persons ; namely, to the ever-longing and ever-disappointed horticul- turists of cities and towns, whose gardens are a tea-pot or a flower-pot, emulous of the gardens of Adonis, a smoked balcony, a darkened and smoky area, containing a few square yards of grass or gravel, or the somewhat freer, yet still poisonous inclosure of a square. On this, however, I can do little more than suggest, or rather produce, a faulty and im- perfect notice, as a stimulus to those who can do better, and to whom, perhaps, the having cause for blame will, as is common, prove the most engaging inducement. It is true, that professional gardeners are frequently consulted on this subject, by the anxious prisoner of towns longing for the sight of something that resembles the fair face of nature ; and it is equally true, that such advice as they do give is limited, and often worthless. Yet there must be some gardener or horti- culturist who knows incomparably more on this subject than I can pretend to do ; and my end will be accomplished, if some such person will supersede a very bad catalogue by a very good one. If even he shall meet dispraise instead of thanks, he will have the satisfaction of having attempted to multiply the innocent amusements of his race. JULY— SEPT., 1829. F 66 On the Cultivation of It is as unnecessary to point out the general antipathy which vegetables in general have to towns, as it is at present difficult to explain the cause. It would be somewhat extraordinary, indeed, if it were understood ; when what is called the science of botany is solely occupied in making and changing names and arrangements, as if its objects were not only dead matter, but useless specimens of forms ; and when the conventional, or perhaps necessary limitations of the far other valuable science of horticulture, together with the extent of this pur- suit, and its no very remote origin as a science, seem to cut it off from the more refined anatomical and physiological inquiries necessary to illustrate this, and far more in the his- tory of this great division of animated nature. But, indeed, if the immediate or proximate cause is un- known, we are scarcely better informed as to the remote and acting one. It is not exclusively want of light, because as much light can be obtained in towns as in the country ; and '* want of air" is a term without meaning. If it is excess of carbonic acid, or indeed if it be any other derangement of the proportions in the constituents of the atmosphere, why cannot our refined chemistry detect this ? It is said to arise from smoke, and, in our own towns, to depend exclusively or espe- cially on coal smoke. Certainly this is not the exclusive cause ; since similar effects take place in towns where wood is burnt, and where comparatively there is little smoke of any kind ; nor is it easy to conceive how smoke acts, when we know what its nature is, and know that this very substance can be applied largely to plants in a solid state, or mixed with water, without injuring them in the same manner. It is pro- bable, however, that the clue must be sought in that which has not simply been neglected, but denied ; and that is, the sensations, the vital power, or nervous system of plants ; denied by those who have, through all time, explained the actions of plants by mechanical principles, by the immense majority of botanists, or nearly by all ; and in exactly the same deep philosophical spirit which, in the hands of a few others, assigned the actions of animals to similar causes. But to pass what cannot at present be explained, it is an object of interest to trace the effects, be the cause, whether Plants in Towns. 67 proximate or remote, what it may ; as one, at least, of these concerns the purpose of this brief note. On this, however, I must content myself with a very few slight remarks, as I dare not prolong this postscript. In London, as in Edinburgh and Glasgow, or other rapidly increasing towns, it is easy to follow the gradually widening circle of this noxious atmosphere, and in certain parts of those also its increase of noxious power. The receding of nurseries from the precincts of these towns is the evidence of the former ; and, of the latter, he who will search, will find proofs enough, in the gradual extinction of plants which had gone on resisting through years. I know not, in London, a more distinct example of the last than in the garden of Mr. Bentham in Westminster, which, once bearing many fruits and flowers, even in abundance and perfection, is now gradually yielding to the increasing influence, and will probably soon be reduced to that limited number of plants which seem endowed with the power of resisting these effects. And it has not been uninteresting to trace the progress ; the disappearance or non- production of the stone fruits there cultivated, having been among the first effects, and that (if, as I believe, I am correct) having been followed by their flowers ; the currant and goose- berry afterwards suffering in the same order, and some or other of the flowering plants and shrubs, together with some trees, annually and successively becoming more enfeebled, or ceasing to live. But, to omit a long detail, the downward progress of this garden will aid in illustrating the appended imperfect cata- logue ; though I must remark, that it does not afford a rule for all London, as the vicinity of the Park secures it probably from many consequences as to the tenderer town plants ; just as Grosvenor and Lincoln's Inn squares are favourable to many species that would not exist in St. Paul's churchyard. It would have been useful could we have discovered any ge- neral principle on which to determine beforehand what plants would succeed in these situations. And, perhaps, one might be found, should the investigation be pursued to a far greater increase of this meagre catalogue. At present it presents none, whether as relates to natural affinities, orders, or even genera, F 2 G8 On the Cultivation of or as it concerns origin, climate, or hardiness to other injuries. One only remark, at all bearing on this question, has been made, and it is no less unexpected than remarkable. It is, that very many of the Alpine plants will thrive in the most confined allies, in the garrets of working mechanics for example, where almost every other plant dies ; and without seeming at all affected by a change, so enormous in every sense, as to almost render the fact incredible. How far this sort of endurance extends through this geographical division of plants has not however been ascertained ; but it offers one broad basis which will save much detail in the following catalogue. Such as I have been able to make this catalogue, and chiefly from observations collected in Glasgow, the most smoky town in Great Britain, here it is ; though I cannot pretend to say, out of all these, which are the most and which the least hardy in this sense. I have no doubt that many gardeners can ma- terially enlarge it, and I must hope that some one will do so 5 supplying also that proportional scale, towards which I could but have added so few fragments, that I thought them better omitted altogether. These plants, of course, are ornamental ones, since ornament is the object ; and I have used the most popular rather than the botanical names, as the end was that they should be generally understood. The latter are intro- duced only where there was no English popular name, or where that name itself was little known : — Laburnum. Lilac. Hawthorn. American Ivy. Ivy. Jessamine. Lily of the valley. Solomon's seal. White lily. Orange lily. Yellow lily. Turncap lily. Periwinkle. Both species. Matricaria parthenium, or Feverfew. Valeriana pyrenaica. — rubra. Bladder senna. Alchemilla vulgaris. — alpina. Scilla nutans, or Wild hyacinth. Stace armeria, or Thrift. Scarlet bean. Marigold. Common bean. Box. Mignonette. Sweet William. Plants in Towns. 69 Mule pink, or Dianthus. In general, including all or most pinks and carnations. Rocket. Hollyhock. Lavatera. Elder. Dogwood. Poppies : But it is remarkable that, if the seeds are sown in the border and in the gravel both, those in the border will often fail, while those in the gravel succeed. Saxifraga hypnoides. — oppositifolia. And many more. Alyssum. More than one of this genus. Sunflower. Crocus. Snowdrop. Daffodil, and others of Narcissus. Aucuba japonica. Mimulus ringens. Wallflower. Cheiranthus : The whole of the stocks or gilli- flowers, I believe. Auricula. Onopordum acanthium. Mespilus pyracantha. Yellow lupin. Sweet peas. Nasturtium ; Both species. Convolvulus : tricolor, and more of this genus. Gum Cistus : Probably more of cistus. Such Alpine plants as I have thought fit to omit may be added ; and it is best perhaps to leave even the blank I might fill, that others may, in trying, add species of which I am ignorant. I may add, that the vine continues to bear fruit where the stone fruits have ceased, and even where the goose- berry and currants appear to be verging to an end. Allow me yet to hope, before closing this paper, that some competent person will also favour the public, through your Journal, with a catalogue of such flowers as will succeed in thickets and woods, or within the shade and influence of our various trees and shrubs. Every one knows the disagreeable blank so often caused in these situations by the want of flowers or flowering shrubs ; not seldom, by the entire absence of plants of any kind ; and he who has busied himself in orna- ment of this nature, has often had to regret that he could not remedy this defect, nor obtain the requisite information. There are few gardeners probably who have not at some time been applied to for advice on this subject, as well as the former ; and most assuredly the advice is not obtained, since the defect continues. It cannot be irremediable ; and if the knowledge 70 On Winter Gardens. does not exist, it can at least be procured by the contribution of many, if not by the efforts of one. But as I am ashamed of the scantiness of my own list, deprived of the means of collecting one, I will not add a dozen or two of names, when I hope soon to see a far greater number. Still there is another subject connected with ornamental gardening, which has been strangely neglected — strangely, in a climate like ours, and still the more remarkably, when it is recollected that the fashions of our country render winter a sort of conventional summer, as they also reverse the proposi- tion ; or that the time allotted to the rural residence is that in which all the brightest flowers of summer have disappeared ; and, still more, that in which the great mass of vegetation is dormant or dead. To the great bulk of the opulent, the flower garden and shrubbery, often far more, are lost to all but the gardener ; it is ornament and expense, without comparative use. Why, then, are the autumnal and winter gardens neglected, while every thing is reserved for spring and summer ? Who, among the higher classes, see the lilac and laburnum flower in their own grounds ? How many see even the rose ? Yet nearly two centuries are past since this recommendation, even to the de- tails, such as the knowledge of that day could make them, was urged by Lord Bacon, urged, yet neglected, since there is scarcely a winter garden in Great Britain, and certainly not one such as might be constructed with a very small degree of attention. The reason is not in the ignorance of gardeners, since they do possess knowledge enough of the plants which would serve this purpose ; it must be sought partly in their neglect, but chiefly in the neglect, and more in the ignorance, of rural pro- prietors, who do not seem aware that such a thing is possible. Had they learned what and how to command, their servants would have learned to obey. And while such gardens may be constructed, it is surely superfluous to remark what pleasures might be derived from a spot which excluded the aspect of winter, even did it but cheat us with a cold semblance of sum- mer. How this may be effected, and what are the evergreens and the successions of late flowers, it is not my purpose here On Winter Gardens. 71 to point out, having perhaps already protracted this paper beyond due bounds. But my wish is, that those whose proper business it is would publish such catalogues in those works which are in every one's hands, and direct the attention of proprietors and gardeners to those plants which, if known, are not pointed out to the ignorant ; urging further the advantages of such an improvement, and adding such details respecting choice, disposition, succession, and so forth, as would here, and in hands like the present, be misplaced. I am, &c. J. Mac Culloch. On the Construction of the Galvanic Battery. I beg leave to present to the Editor of the Quarterly Journal an account of a galvanic battery invented by myself some years since, which has been adopted by several of my country- men of the United States of America, and approved by many chemists in Paris, who have seen its operation. The general description is this: — The copper plate is formed into a narrow cell in which the zinc is inserted and prevented from contact by bits of - varnished wood. A number of pairs thus arranged are suspended from a common bar of wood by wires, the communication being made as usual between each zinc and the contiguous copper by a metallic slip. It is easy to see that by plunging the cells into a vessel containing the liquid until they are filled, and lifting them out, the instrument will be in action, which may be suspended by emptying them, and again renewed by filling them in the same manner. The facility of operation is greater than that of any other form I have ever seen, and a great power is saved by their complete insulation ; in addition to which, the necessity of separate cells of glass, porcelain, &c. is superseded, which are expensive, troublesome, and fragile. The instrument may be constructed by any tin worker ; and the zinc plates, when worn, can be renewed at a very trifling expense. I shall pass on to the minute description, for which purpose I send drawings. 72 On the Construction of the Galvanic Battery, 3 i s / W 4 s ,.B « _ . <*«' T, Trough of wood. B, Bar of support. U, Uprights, with a notch at top to re- ceive the bar. C, Copper cell, to which W, Suspensory piece, is soldered. Z, Zinc plate. S, Copper slip soldered to the copper cell at one end, and next zinc plate at the other end. Fig. 1 represents the form of the zinc plate, which is rhom- boid al, with a projection at the upper part, to which is sol- dered one end of the slip connecting it with the next copper plate. It is made of rolled zinc. Fig. 2 gives the form of the copper plate, which is formed into a cell open at top. In order to form it the copper should be cut in the shape given at On the Construction of the Galvanic Battery. 73 Fig. 3. Little slits are made at the lower angles and in the middle, represented by a a a a, and the copper, being then bent in the direction of the dotted lines, will produce the cell. It is soldered on the lower and sloping sides. At the back of the copper plate is soldered a piece of metal, w (iron, well var- nished), by which it is suspended from the common bar repre- sented by b. To one side also is soldered the slip s, connect- ing it with the zinc of the contiguous pair. Fig. 4 gives a perspective view of a single element. The copper cell, c, is represented with its suspensory piece, w, attached to the bar, b, by two screws. The zinc plate z is inserted in it, and prevented from contact by bits of wood with a slit in one side, which have been boiled in copal varnish. The copper plate suspensory and connecting slip are all well varnished exteriorly, and the soldered part interiorly. Fig. 5 represents an end view of the whole instrument in action. Fig. 6 giving the front of the same. T being a trough of wood, well joined and lined with cement of wax and resin, at each end of which is an upright support of wood, with a notch in the top large enough to receive the end of the bar to which the plates are attached ; wires proceeding from the opposite poles convey the electric fluid where it is wanted. To suspend the action, we have only to lift the bar out of the notches and empty the fluid either into the same or another trough. To renew it, plunge the cells until filled into the trough, and lifting them out, place the ends of the bar into the notches. I have constructed several instruments of different dimensions ; and comparing their action with those upon other plans, find a very great superiority of force in favour of my own. The im- portance of insulation even for combustion is demonstrated by placing in the circuit a wire of a given thickness, which, while the plates remain immersed in the fluid, will show no sign of combustion, but when they have been lifted out, is instantly heated to a high degree. Should a" plate prove defective, it may be replaced with but little trouble ; and an immense power occupies but little space, the cells being only half an inch wide, and not more than a quarter from each other. The action also, being renewed or suspended at plea- 74 Mr. Graham's Experimental Researches sure, gives room for the professor to explain. If you should think this description worth inserting in your Journal, you will oblige Yours respectfully, Robert Greenhow. A short Account of Experimental Researches on the Diffusion of Gases through each other, and their Separation by mecha- nical means. By Thomas Graham, AJM., F.R.S.E., Lec- turer on Chemistry, Glasgow. Fruitful as the miscibility of the gases has been in interesting speculations, the experimental information we possess on the subject amounts to little more than the well established fact, that gases of a different nature, when brought into contact, do not arrange themselves according to their density, the heaviest undermost, and the lightest uppermost, but they spontaneously diffuse, mutually and equably, through each other, and so re- main in an intimate state of mixture for any length of time. The beautiful illustrations of Mr. Dalton, by which this law was first developed, have rendered it familiar to everyone. The subsequent experiments of Berthollet were made with uncom- mon care, and in most favourable circumstances, yet it is diffi- cult to draw more from them than the same general fact ; unless perhaps that hydrogen is much more penetrating and diffusive than any of the other gases*. It is sufficiently evident, however, from Berthollet's experiments, that, in cases of gaseous mixture which are exactly similar, corresponding results may be expected, or that the diffusion is not accidental, but subject to fixed laws. In the prosecution of further inquiry into the laws of the diffusion or miscibility of gases, much use was made of a * Berthollet's experimental paper is contained in the Mem. d'Arcueil, vol. i. p. 463 ; but the whole experiments are given in a tabular form in Dr. Thomson's System, vol. iii. p. 33. on the Diffusion of Gases, 8rc. 75 cylindrical glass receiver A, 9 inches in length, and /O^ 0.9-inch internal diameter, divided into 150 equal parts, and provided with a stopper B, fitted into the mouth of the receiver by accurate grinding. The stopper was perforated longitudinally, cavity cylindrical, 0.34-inch in diameter, and 1.8 in length. Into the cavity of the stopper there was again ground a short piece of stout tube, having a bore of 0.07 or nearly y^.-y inch, and bent into a right angle in the middle ; such as C. These were the dimensions of tube A ; but after several experi- ments that tube was laid aside, and a second and a ... wider tube, of 0.12-inch bore and 2 inches in I L^ c length, was ground into the aperture of the large stopper B, and bent in the middle, like tube C. B I. — On the Diffusion of the different Gases into atmos- pheric Air. The receiver, above described, was filled in succession with various gases in a state of purity, and supported in a horizontal position upon a frame, within a box, with the end of the bent tube pointing upwards, Fi 9- I- when the contained gas was r~ heavier than air (fig. 1), and ^- downwards, when the gas was lighter (fig. 2), to avoid any tendency of the gas to flow out of the receiver. After the gas had been allowed to diffuse into the air through the tube for a certain time, the receiver was transferred to the pneumatic trough, and the quantity of air which had entered, and gas that remained, ascertained. Two or three and sometimes more experiments were made on each gas, and the results found to be regular, or to vary within moderate limits. (1). After diffusion for ten hours, through tube I, there 76 Mr. Graham's Experimental Researches was found in the receiver, of which the capacity = 150 parts — of Hydrogen gas (sp. gr. 0.0694*) . . 8.3 parts. Carburetted hydrogen of marshes (sp. gr. 0.5555") . 56 Ammoniacal gas (sp.gr. 0.59027') . . 61 defiant gas (sp. gr. 0.9722') . . .77.5 Carbonic acid (sp. gr. 1.52 7 7 # ) . . .79.5 Sulphurous acid (sp. gr. 2.2222') . . 81 Chlorine (sp.gr. 2.5) ... . 91 (2). After diffusion for four hours through tube I — in 152 parts there was found — of Hydrogen gas . . . ,28,1 Carburetted hydrogen . . 86 Ammoniacal gas . . .89 defiant gas . . , 99 Carbonic acid . . . . 1 04 Sulphurous acid . . . 110 Chlorine 116 There have, therefore, left the receiver in the same time — of Hydrogen gas . . . 1 23 . 9 parts. Carburetted hydrogen . . .66 Ammoniacal gas . . . 63 defiant gas . . . .53 Carbonic acid gas . • . 48 Sulphurous acid . . .42 Chlorine .... 36 In deducing the comparative diffusiveness of the different gases from the table above, it is necessary to keep in mind the diminishing rate, according to which the latter portions of the gas leave the receiver. It was determined, with precision, in the case of olefiant gas, that that gas continues to leave a receiver, by diffusion, according to the same diminishing rate which holds in mechanical exhaustion by the air-pump. Hence the initial diffusions of the gases are even more varied than the numbers of the table. As much hydrogen gas left a receiver in two hours, as of carbonic acid in 10 hours, Hence the former gas is five times more diffusive than the latter. In all cases the gases were necessitated to diffuse in opposition to the solicitation of gravity. Yet carburetted hydrogen and ammoniacal gases left the receiver in greater proportions than 07i the Diffusion of Gases, 8fc. 77 defiant gas did, although the diffusion of the former gases was more opposed by mechanical causes. It is evident that the diffusiveness of the gases is inversely as some function of their density — apparently the square root of their density. f The results, however, are much influenced by the mechanical resistance arising from gravity, which is not constant in gases of different densities, the position of the receiver remaining the same. The effect of the position of the receiver may be con- ceived from an experiment on hydrogen gas. The re- ^-x ceiver, filled with hydrogen gas, was placed in an upright instead of a horizontal position (see figure). Other circumstances being the same as in the experiment of table (1), of 150 parts hydrogen 22.1 were found re- maining in the receiver after diffusion for ten hours, instead of 8.3 parts, as in that experiment. Although the stoppers fitted precisely, the additional precaution of luting the joinings was attended to. The properties of the receiver, too, were found not to be peculiar to it. II. — On the Diffusion of mixed Gases into atmospheric Air. In the case of an intimate mixture of two gases, I was anxious to learn if each gas left the receiver, independently of the other, in the proportion of its individual diffusiveness — which would be a step gained in the solution of the important problem of the analysis of mixed gases by mechanical means. For this purpose, the receiver was filled with 75 vols, hy- drogen + 75 vols, defiant gas, agitated and allowed to stand over water for 24 hours, that the mixture might be as perfect as possible. The receiver being then placed in the usual position, the mixed gases were allowed to diffuse into the air for ten hours. The receiver thereafter was found to contain Hydrogen gas . . . 3.5 Olefiant gas . . .56.6 Air 89.9 150.0 78 Mr. Graham's Experimental Researches There have left the receiver — of Hydrogen gas . . 71.5 out of 75 parts. Olefiantgas . . .18.4 75 The more diffusive gas has, therefore, separated from the other, and left the receiver in greatest proportion. Now, when the receiver contains nothing but pure olefiant gas, 72.5 parts of that gas leave the receiver in the circum- stances of the preceding experiment. Hence, when the re- ceiver is half filled with olefiant gas, we would expect the half of 72.5 parts, or 36.25 parts to leave the receiver, and this happens when the complementary 75 parts are common air. But instead of 36.25 parts, only 18.4 olefiant gas leave the receiver in the last experiment. The disparity between the diffusion of each of the mixed gases, in that experiment, is actually greater than the disparity between the solitary diffu- sions of the same gases. In the case of mixed gases, the law is— that the more dif- fusive gas leaves the receiver in a greater proportion than in the case of the solitary diffusion of the same gas, and the less diffusive gas in the mixture in a less proportion than in its solitary diffusion — a law of the diffusion of mixed gases, which was confirmed in upwards of forty experiments on di- verse gaseous mixtures. Some of these experiments I shall subjoin. (1.) The receiver was charged with Carbonic acid . . . ^ 5 \ - 150 Hydrogen . . . .75) which were allowed to mix intimately over-night. The mix- ture was afterwards allowed to diffuse into the air through the tube for ten hours. Position horizontal, mouth of tube downwards. Thereafter contained, Carbonic acid . . . 45 Hydrogen . . . . 4.65 Air 100.35 150.00 In this experiment, a portion of the carbonic acid may have flowed out, for at the end of the experiment the density of the gaseous mixture was greater than that of the atmosphere, while the mouth of the tube opened downwards. on the Diffusion of Gases, fyc. 79 (2.) Receiver charged with Carbonic acid . . . 1021 = ^ Hydrogen . . . 50 J With tube II. Position of receiver horizontal, mouth upwards. After diffusing into the atmosphere for four hours, contained, Carbonic acid ' . . . 76 Hydrogen . ' . ' . . 10.3 Air .... 65.7 152 (3.) Receiver charged with Carbonic acid . . . 761 j 52 Carbur. hydrogen (of marshes) 76 J Tube II, mouth upwards. After four hours, contained, Carbonic acid . . .57 Carbur. hydrogen . . 35.3 Air . . ' . . ' . 59.7 152 Have left the receiver, Carbonic acid . . .19 Carbur. hydrogen . . . 40.7 or, twice as much carburetted hydrogen as carbonic acid has left the receiver. Of these gases individually, there left the receiver in the same circumstances, Of Carbonic acid . . . 48 Carburetted hydrogen . . 66 (4.) Receiver charged with Carbonic acid . . . 521 _ .,« Carburetted hydrogen . . 100 J 10i5 Position, &c. as in preceding experiment. After four hours, contained, Carbonic acid . . .39 Carbur. hydrogen . . 51.6 Air ... . 61.4 152 Have left the receiver, Carbonic acid Carbur. hydrogen . . 13 •. 48.4 80 Mr. Graham's Experimental Researches . . 31, . 121/ (5.) Receiver charged with Carbonic acid Carbur. hydrogen Position, &c. as above. After four hours, Carbonic acid ... 23 Carbur. hydrogen . . .71 Air .... . 58 152 152 Have left the receiver, Carbonic acid ... 8 Carbur. hydrogen . . 50 These three last experiments form a series. Suppose we had a mixture of two gases, of the same densities as carbonic acid and carburetted hydrogen, in equal volumes, but which could not be separated from each other by chemical means. Allow this gaseous mixture to diffuse for a certain time, as in Experiment 3, into a gaseous or vaporous atmosphere, which may afterwards be absorbed or condensed with facility. On condensing this atmosphere, there would remain a mixture, consisting of two parts of the light, and one of the heavy gas. By a similar diffusion of the mixture thus obtained, we would procure a third mixture, consisting of four parts of the light, and one of the heavy gas, (Experiment 4.) By a third diffusion, a mixture would be obtained of six or seven of the light, and one of the heavy gas, (Experiment 5.) In this way a specimen of the light gas would at last be eliminated, by a species of rectification, in a state of tolerable purity. On the other hand, if a specimen of the dense gas be de- sired, a converse series of operations must be pursued. What remains in the receiver after diffusion must be preserved, accumulated, and submitted again and again to diffusion. (6.) Receiver was charged with defiant gas . . . . 76] Carburetted hydrogen . 76 ^ After four hours, contained, defiant gas . . . 47.75 Carbur. hydrogen . . 41.40 Air . . . . . 62.85 152 on the Diffusion of Gases, fyc. Have left the receiver, 81 Olefiant gas Carbur. hydrogen 28.25 34.60 III. — Diffusion of Gases into other Atmospheres than common Air, (1.) A phial, A, of 5.2 cubic inches, provided with a per- forated cork, was filled with an intimate mixture of olefiant and hydrogen gases in equal proportions. The phial being held with its mouth undermost, a glass tube of 0.12 inch bore was thrust through the cork, and likewise quickly inserted into Fig. I. A the perforated cork of another bottle, B, of 37 cubic inches, containing carbonic acid gas. The whole was then sunk in water, till the surface of the water, a a, {Fig. 2.) rose above the joinings. After ten hours, the upper phial was removed, and its contents washed with lime-water. There remained a mixture, consisting of Olefiant gas Hydrogen 12 3.1 There can be no doubt that the olefiant gas would have been obtained in a state of greater purity, had not the diffusion of JULY— SEPT., 1829. . G 82 Mr. Graham's Experimental Researches the hydrogen gas been greatly impeded, 1st. From the direc- tion in which it took place, downwards ; and, &dly. From the density of the medium into which it diffused. Had the mixture of olefiant gas and hydrogen been allowed to diffuse upwards, and into an atmosphere of specific gravity intermediate between that of its constituent gases — into steam or ammoniacai gas, for instance, circumstances would have been most conducive to the unequal diffusion and separation of the mixed gases. (2.) Hydrogen gas, in a tall receiver, is expanded by sul- phuric ether, I find, four times more rapidly than common air. Mr. Leslie had already observed, that ice evaporates twice as rapidly in hydrogen gas as in common air ; and he and Mr. Dalton found the cooling powers, or mobility of the different gases to be inversely as their density. (3.) Gases permeate with increased facility in both direc- tions through the pores of porcelain tubes at high temperatures (Priestley), because, I believe, their tendency to diffusion, which is inversely as their density, is vastly increased by their rarefaction, and not from any dilatation of the pores of the por- celain, which must be utterly trivial in the most intense heat. (4.) A tall receiver was jths filled with a mixture of 2 hy- drogen + 1 oxygen, which had remained mixed for three weeks, but was found sensibly pure before the experiment. A little ether being thrown up into the receiver, the experimental mixture rapidly expanded. The first bubble projected from the receiver by the expansion was received, deprived of all ether-vapour by washing, and being exploded, left half its bulk of pure hydrogen gas. (5.) The vapour of water appears, from the following expe- riment, to be more diffusive than the vapour of alcohol, as might be expected from the densities of these vapours. Of dilute alcohol (0*964), three ounces were exposed to spon- taneous evaporation in a cylindrical jar two inches deep, and the same quantity in a jar six inches deep, but otherwise similar, the mouths of both- jars being loosely covered with paper. When each of the vessels had lost half an ounce by evaporation, the remaining liquor was examined and found to contain sensibly more alcohol in the case of the deep than of on the Diffusion of Gases, Sfc. 83 the shallow jar. The difference, however, was altogether in- sufficient to enable us to account for the well known experi- ment of the concentration of alcohol in a bladder, by referring it to the superior diffusiveness of water-vapour. But it is conceivable, and the subject is at present under investigation, that imperceptible pores, or orifices of excessive minuteness, may be altogether impassable (by diffusion) by gases of low diffusive power, that is, by dense gases, and passable only by gases of a certain diffusive energy. Hydrogen gas certainly escapes from a bladder more rapidly than any other gas, and probably from diffusion, as the place of the hydrogen is found occupied by common air. But to these investigations, and to certain theoretic considerations, I hope again to recur in a future paper. Observations on the Oxidation of Phosphorus, By Thomas Graham, A.M., F.R.S.E., Lecturer on Chemistry, Glasgow. We are at present in possession of several curious facts re- specting the insensible combustion of phosphorus at low temperatures. 1. In pure oxygen gas, under the atmospheric pressure, and at temperatures below 64°, the usual white smoke is not seen around phosphorus in day-light, and it is not luminous in the dark. No absorption of oxygen takes place. 2. A slight expansion of the oxygen gas, produced by dimi- nishing the pressure upon it two or three inches below the usual pressure of the atmosphere, occasions phosphorus to be acted upon by pure oxygen, and to undergo slow combustion. 3. By diluting oxygen with certain gases, such as hydrogen, azote, protoxide of azote, carbonic oxide, carbonic acid, &c, the oxygen becomes capable of supporting the slow combus- tion of phosphorus even under the atmospheric pressure, as well as when rarefied by reduced pressure. Hence phosphorus is luminous in common air. The proportion of foreign gas necessarily varies according to the nature of the gas. G 2 84 Mr. Graham's Observations on 4. Certain other gases do not qualify oxygen to act upon phosphorus at low temperatures, in whatever quantity they may be added to it. This is the case with olefiant gas, and with azote obtained by the action of a paste of sulphur and iron on common air. The first and third of these facts have been known for a long time ; the second was discovered by M. Bellani de Monza; and the fourth appears to have been first observed by M. Thenard (Traite de Chimie, t. i. p. 236, where the subject is treated at length). In experimenting upon this subject, another curious fact was noticed. The presence of a minute quantity of certain gases and vapours entirely prevents the usual action of phosphorus upon the oxygen of common air. Thus the slow combustion of phosphorus does not take place at all, at the temp, of 66°, in mixtures of Volumes of air. 1 volume olefiant gas and . . .450 1 ditto vapour of sulphuric ether and 150 1 ditto vapour of naphtha and . 1820 1 ditto vapour of oil of turpentine and 4444 A stick of phosphorus was repeatedly left for upwards of 24 hours over water in air containing only one-four hundredth part of its bulk of pure olefiant gas, during the hot weather of July and August 1828, thermometer frequently above 70°, without diminishing the bulk of the air in contact. A slight expansion, amounting sometimes to T ^th part, occurred on several occasions. A stick of phosphorus, with a few drops of water, was corked up in a large retort, 213 cubic inches in capacity, and containing common air, with which -^th of its bulk of pure olefiant gas had been mixed. During three months the phosphorus never became luminous, although its surface was gradually covered with a thin white crust. The water present was found to have become slightly acidulous. The influence of a minute quantity of ether-vapour, in ex- tinguishing the combustion of phosphorus at low temperatures, may be exhibited in a striking manner. Introduce two or three moist sticks of phosphorus into a pint-stoppered phial, into which, when filled with the white fumes, pour a little ether- the Oxidation of Phosphorus. 85 vapour from the ether bottle. In a few seconds the fumes entirely disappear, and the air around the phosphorus becomes perfectly transparent. If the bottle is now stopped, white fumes do not again appear in it, till the ether has passed entirely into acetic acid by combining with oxygen, which requires a few days. Phosphorus is not luminous in the dark in air slightly im- pregnated with any other essential oil, as well as oil of turpen- tine. In an open two-ounce phial, phosphorus will appear brightly luminous in the dark; but the moment the phial is stopped with a cork, which has formerly confined an essential oil, and still sensibly retains its odour, the light begins to fade, and disappears entirely in a few seconds. The light from phosphorus in air at 63° F. is extinguished by the addition of 4 per cent, of chlorine gas, or 20 per cent, of sulphuretted hydrogen. The vapour from strong alcohol of about 80° in temperature extinguishes luminous phosphorus. But the vapours from camphor, sulphur, iodine, benzoic acid, carbonate of ammonia, iodide of carbon, do not produce that effect, — thermometer 67°. Held in the mouth of a bottle, containing strong muriatic acid, phosphorus appears to become more brilliant. But this is not the case with nitric or nitrous acids, which sensibly impair the light. The vapour from the liquor condensed in the vessels of the Portable Oil Gas Company, and coal gas, protect phosphorus from oxidation. It is evident from these experiments, that phosphorus cannot be used to withdraw oxygen from gaseous mixtures, containing defiant gas, or the different compounds of carbon and hydro- gen allied to that gas. It may be employed as a test of their presence even in very minute quantity. The influence of those gases in preventing the oxidation of phosphorus in air appears even at elevated temperatures. Phosphorus may be melted and kept for any length of time at 212°, without alteration, in air containing an equal volume of olefiant gas. In three parts air, with two parts sulphuric ether, phosphorus became faintly and transiently luminous in the dark at 215°, — weak lambent flashes, which disappeared entirely at 210°, and were repeatedly revived and extinguished by alternately elevating and lowering the temperature between 86 Mr. Graham's Observations on these limits. A pretty strong combustion occurred at 240°. The following table exhibits the temperature at which phos- phorus first becomes faintly luminous in the dark in air con- taining different gaseous substances : — In 1 volume of air and 1 volume of defiant gas, at 3 „ 2 „ vapour of ether, at 111 „ 1 , vapour of naphtha . 166 „ 1 „ vapour of turpentine, at 200° F. 215° 170° 186° The manner in which the influence of these gases is modified by barometric pressure is the most curious part of the subject. The proportion necessary to prevent combustion depends en- tirely upon the density of the gases. Thus, although less than one four-hundredth part of olefiant gas prevents the combus- tion of phosphorus, barometer 29 inches, phosphorus has been observed in a luminous state, under the pressure of half an inch mercury, in air containing so much as an equal volume of that gas. In the following table the first column of fractions expresses the largest proportion of olefiant gas, in a mixture of air and that gas, which allows phosphorus to be luminous under the pressure placed against it. A greater proportion of olefiant gas extinguishes at that pressure. PEIOSPHORUS LUMINOUS. Proportion of olefiant gas. Olefiant gas + Air Barometric pressure. * + 2 1 *4 inches I + 4 2-3 T^ + 9 3-2 ft + 19 5-0 6 -4- 29 10-3 £ + 39 12-1 M + 49 16-5 ik + 99 25-5 5^5 + 199 26-4 fik + 449 290 Thermometer at 70°. When phosphorus is luminous above the mercurial column in a barometer tube at the greatest pres- the Oxidation of Phosphorus. 87 sure possible for a particular mixture, a slight inclination of the tube from its vertical position, which has the effect of con- densing the gas, extinguishes the light; while, on bringing back the tube to its vertical position, the phosphorus again becomes luminous. The influence of other vapour on the oxidation of phos- phorus at various pressures did not present any material dif- ferences from that of defiant gas just detailed. Naphtha and turpentine vapours appeared to lose their negative influence very rapidly as the pressure was reduced. Carburetted hydrogen of marshes impedes to a certain degree, but does not altogether prevent, the oxidation of phos- phorus. Its effect vanishes over a mercurial column of a few inches, a circumstance which will be attended to with advan- tage in removing, by means of phosphorus, the small portion of oxygen generally found in that gas. The sulphuret of phosphorus and phosphuretted hydrogen gas are likewise protected from oxidation, to a certain extent, by olefiant gas, sulphuric ether, &c, although less powerfully than phosphorus, in proportion to their higher accendibility. The oxidation of potassium appears likewise, from several comparative experiments, to be considerably retarded in dry air, containing a fourth or a fifth of its bulk of ether-vapour or olefiant gas, particularly of the latter. A piece of potassium, about the size of a pea, confined for a month in dry air, con- taining a fifth of its bulk of olefiant gas, was merely covered by a thin coating of grey oxide ; while another piece of potassium, in similar circumstances, with the exception of the olefiant gas, was deeply penetrated with fissures of a kernel white. The interference of those gases in preventing the oxidation of phosphorus, &c, is probably allied to the influence of the same and several other gases in preventing the accension of the explosive mixture of oxygen and hydrogen by the electric spark, first observed by Sir H. Davy (Essay on Flame), and since confirmed and investigated by Dr. Henry (Phil. Trans. 1824), and Dr. Turner (Edin. Phil. Journal, vol. xi.) Ole- fiant gas was found to act most powerfully, half a volume pre- venting the combustion of the explosive mixture, that is, defending the hydrogen from oxidation ; and here, as in the 88 Notice of the case of phosphorus, the olefiant gas seemed to suspend the usual action between the supporter and combustible, without undergoing any change itself. If the nature of this influence of olefiant gas is the same in both cases, it forms a singular and interesting subject of inquiry, readily accessible in its most minute details in the case of phosphorus. Notice of the singular Inflation of a Bladder. By Thomas Graham, A.M., F.R.S. E., Lecturer on Chemistry, Glasgow. In the course of an investigation respecting the passage of mixed gases through capillary openings, the following singular observation was made. A sound bladder with stopcock was filled about two-thirds with coal gas, and the stopcock shut ; the bladder was passed up in this flaccid state, into a bell-jar receiver filled with car- bonic acid gas, and standing over water. The bladder was thus introduced into an atmosphere of carbonic acid gas. In the course of twelve hours, instead of being in the flaccid state in which it was left, the bladder was found distended to the utmost, and on the very point of bursting, while most of the carbonic acid gas in the receiver had disappeared. The bladder actually burst in the neck, in withdrawing it from under the receiver. It was found to contain 35 parts of carbonic acid gas by volume in 100. The substance of the bladder was quite fresh to the smell, and appeared to have undergone no change. The carbonic acid gas, remaining without in the bell- jar, had acquired a very little coal gas. The conclusion is unavoidable, that the close bladder was inflated by the insinuation of carbonic acid gas from without. In a second experiment, a bladder containing rather less coal gas, and similarly placed in an atmosphere of carbonic acid gas, being fully inflated in fifteen hours, was found to have acquired 40 parts in 100 of this latter gas. A small portion of coal gas left the bladder as before. A close bladder, half filled with common air, was fully in- flated in like manner, in the course of 24 hours. The en- Singular Inflation of a Bladder. 89 trance of carbonic acid gas into the bladder depends, therefore, upon no peculiar property of coal gas. The bladder, partially filled with coal gas, did not expand at all in the same bell-jar containing common air or water merely. M. Dutrochet will probably view, in these experiments, the discovery of endosmose acting upon aeriform matter, as he observed it to act upon bodies in the liquid state. Unawar j of the speculations of that philosopher at the time the experi- ments were made, I fabricated the following theory to account for them, to which I am still disposed to adhere, although it does not involve the new power. The jar of carbonic acid gas standing over water, the bladder was moist, and we know it to be porous. Between the air in the bladder and the carbonic acid gas without, there existed capillary canals through the substance of the bladder, filled with water. The surface of water at the outer extremity of these canals being exposed to carbonic acid, a gas soluble in water would necessarily absorb it. But the gas in solution, when, permeating through a canal, it arrived at the surface of the inner extremity, would rise, as necessarily, into the air in the bladder, and expand it. Nothing but the presence of car- bonic acid gas within could prevent the disengagement of that gas. The force by which water is held in minute capillary tubes might retain that liquid in the pores of the bladder, and enable it to act in the transit of the gas, even after the pressure within the bladder had become considerable. Account of an Apparatus for ascertaining the value of different Alkalis. To the Editor of the Quarterly Journal of Science, &c. Sir, I herewith send you some account of an apparatus which I have employed for many years in ascertaining the value of the different alkalis of commerce ; it is more simple and less liable to variation in its results than any with which I am acquainted as proposed for the use of persons not familiar with the niceties of chemical analysis. You will observe that I 90 Account of an Apparatus for ascertaining have taken the principle of its formation from the paper of M. Decroizelle, in the Annales de Chimie. I am, Sir, Respectfully yours, W. G. Colchester. London, Aug. 28, 1829. The apparatus consists of a glass jar about one inch in dia- meter, containing about five cubic inches, and graduated into inches and tenths ; a dropping tube about seven or eight inches long, divided into thirty equal parts ; a porcelain mor- tar and pestle ; a weight of 100 grains, and a bottle of sul- phuric acid, so diluted that the quantity contained in twenty- two divisions of the dropping tube will just saturate fifty grains of crystallized sub-carbonate of soda. To determine the point of saturation litmus paper may be used, or, what is much more convenient, infusion of cabbage. METHOD OF USE. The sample to be examined having been pounded sufficiently to pass through a coarse sieve, rub up some of it in the porce- lain mortar until it be reduced to a very fine powder ; from this weigh 100 grains and return it into the mortar; add thereto boiling water, a small quantity at a time, and continue to rub it as long as any grittiness appears under the pestle ; suffer it to stand a short time, and pour off the liquid into a pint or half-pint vessel with a lip ; add more boiling water to what remains, and again use the pestle, repeating this to ensure the perfect solution of all the soluble part of the sample, until about half a pint of boiling water has been employed ; transfer the whole into the same vessel, stir it well together, and allow it to stand for the insoluble part to subside; when this is effected, measure off the clear liquor by pouring it into the graduated jar and set it by for use; measure also the remain- der, first shaking it up, and having noted the total quantity, this remainder may be thrown away. Take of the clear solu- tion just one half of the whole amount of the two quantities, and add thereto about a table-spoonful of the infusion of cab- bage ; then, having filled the dropping tube to the upper the Value of different Alkalis. 91 division with the test acid, drop so much into the sample, con- stantly stirring the mixture, as will just change its green colour to crimson ; the quantity of acid used, as indicated by the divisions on the tube, will show the per centage of alkali in the sample, if it be barilla, kelp, or manufactured soda ; but, if the sample be pot or pearl ashes, augment the proportion of test acid used, by adding to the number of divisions indicated by the dropping tube, one half such number, and the total will be the per centage of alkali in such sample. Should it be desired to ascertain the quantity of carbonic acid contained in the sample, we need only note the point at which the solution becomes blue in the foregoing process, and deduct the divisions then indicated by the test tube from the subsequent total amount ; every ten of the remainder will then indicate seven per cent, of carbonic acid, whether of barilla or of pot-ash. The apparatus is made and sold by Mr. Bate, Philosophical- instrument Maker, 21, Poultry. Memoir on the Mean Results of Observations ; read before the Academy of Sciences, April 20, 1829. By M. Poisson. This Memoir is the continuation of that which I inserted in the Additions a la Connaissance des Temps for the year 1827. My object is to add some new developements to that part of it which treats on the probability of arithmetical means between the results of a great number of observations. When there is no reason for believing some more exact than the rest, the mean of them should be taken for the unknown value sought ; and one is naturally led to think that this mean result ap- proaches the nearer to the truth as the number of the observa- tions is more considerable. But La Grange is the first person who subjected this question to mathematical analysis*, and who investigated the probability that the arithmetical mean between any number of observations does not differ from the * Vol. v. of the old Memoirs of the Academy of Turin. 92 M. Poisson's Memoir en the true value by a quantity greater than some assigned limit. To solve it, he supposes known the law of probability of error in the observations, or the values which they may give for the thing which it is sought to determine ; an hypothesis which prevents the formulae deduced from it being applicable and of any use in practice. It is to Laplace we are indebted for hav- ing rendered the probability of the mean result independent of this law in the cases where the observations are numerous ; so that from the sole numerical data of the observations the pro- bability may be calculated of a determinate limit of error to be apprehended in taking this result for the value of the un- known quantity. I hope the details on this subject, into which I have entered in my Memoir, will be well calculated to dissi- pate the doubts which might still remain as to the degree of approximation of this probability*. To form a precise and general idea of the limit to which the mean result of observations approaches indefinitely in propor- tion as the number of them increases, we must suppose the construction of a curve, the ordinates of which are proportional to the probabilities of the values of the unknown quantity, which last is expressed by the corresponding abscissae. If the law of probability change from one observation to another, this curve will change also; and another will be constructed, the ordinates of which will be means, for each abscissa, between those of all the particular curves. This being so, the limit in question, in every case, is the abscissa which corresponds to the centre of gravity of the area of the mean curve. This limit to which the mean result of the observations converges, is not necessarily one of the values of the unknown quantity which have the most probability, and are given most frequently by isolated observations. It may even happen that the proba- bility is altogether none, and that it cannot be given by any single observation ; which, in fact, will be the case if the ordi- nates of all the curves of probability are null for the same abscissa, and symmetrical on each side of it. In the general case where the curve of probability varies from one observation to another, it may also happen that the areas of all the curves * Supplement to Theorie Analytique des Probability, p. 1. Mean Results of Observations. 93 may not have their centres of gravity on the same ordinate ; the abscissa which corresponds to the centre of gravity of the mean area will then vary with the number of observations ; and if this number be divided into several parts, which still consist of considerable numbers, the mean results of these partial series will not be the same, although the error to be apprehended from each of them is very small, and all possess a very great probability. The calculation of mean life is one of the most ingenious applications which has been made of these principles. A great number — a million, for example — of children are considered as born at the same epoch, and the future duration of the life of each infant is assimilated to an eventual gain, of which the probability is unknown. The sums of all the possible durations of life, from zero to the greatest age which men can attain, mul- tiplied by their respective probabilities, and relative to this infant, will then form his chance or his hope of life : conse- quently, mean life will be the sum of these quantities for all the infants divided by the number of them ; now it is easy to see that this quotient is nothing else than the abscissa of the centre of gravity of the mean area, which was mentioned above. Thus, by taking the mean time that an equal number of indi- viduals, born in the same country as the children under consi- deration, have lived, and at a period as near as possible to that of their birth, we shall obtain an approximate value of mean life ; and from these observed durations of human life may be calculated the probability that this value does not differ from the truth, such as it has been defined, by more than a given time. The probability of living to an assigned age is, doubt- less, not the same for a million of infants born at the same period. But it may be admitted that the mean of its unknown values varies but slowly by the extinction of maladies and the improvement of society ; experience alone can teach us if this mean law of probability, and consequently the mean duration of life, remains stationary, or sensibly varies in long intervals of time. It is also by the same principles that the mean advantage, and the probability of it, which may be expected from a very 94 M. Poisson's Memoir on the great number of speculations, is calculated, from the known losses and gains of another very considerable number of similar operations, that is to say, of which the mean law of probability is supposed the same. In other questions depending upon the same theory, where the subject is the greatness of a phenomenon or the measure of any thing which is to be determined by a series of observa- tions, it is supposed implicitly that, among all the values of which this thing is susceptible by its nature, there exists one from which it is equally probable that there will be an equa difference in excess, or defect in each observation ; it is sup- posed, moreover, that this value of the unknown quantity is the same for all the observations, and it is this value, thus defined, that it is sought to discover. That amounts to saying, that the curves of probability relative to all the observations are symmetrical on each side from one of their points, and that this point corresponds to the same abscissa for all these dif- ferent curves. In this hypothesis the centres of gravity of their areas and that of the area of the mean curve will be situated on a common ordinate, the abscissa of which will represent the true value of the unknown quantity. By mul- tiplying the observations, the quantity by which we shall inde- finitely approximate will be constant and independent of their number ; and although their laws of probability may be dif- ferent, their mean result will give a value nearer and nearer to the unknown quantity ; and at the same time, from the whole of the observations collectively, the probability of its degree of approximation may be calculated. But however small may be the error to be apprehended in taking the mean result for the value of the unknown, and however probable may be the limit of this error, it must not be lost sight of that the value of anything drawn from observations is always subordinate to the hypothesis already stated. If any unknown cause render the errors of the instruments or the variable circumstances which influence the phenomena, preponderant one way or the other, or if the thing to be determined varies progressively during the continuance of the observations, this hypothesis will not hold good, and the observations should be rejected as improper for Mean Results of Observations, 95 this determination. It will therefore be important to ascertain by the observations themselves, if they are incompatible with the supposition that has been made, that is to say, with the symmetry of all the curves of probability on each side of a point corresponding to the same abscissa : now, in fact, condi- tions do exist which the observations should satisfy if this sym- metry really have place. Let us suppose, for the sake of illustration, that the mean result of a great number of observations be successively taken away from the particular results of each of them, which will make known their differences each way from the mean, which will be in general very small quantities, positive or negative, the sum of which will be nothing. If we take the sum of any powers of these errors, neglecting the signs, and the sum of the double of those powers, it is evident that the ratio of the first sum to the second will be inversely as the greatness of the errors, and consequently a very considerable quantity. Also, if the square root of the second sum be taken, the ratio of the first to this root will also be a large number of the order of the square root of the number of observations ; that is, if there be, for example, a million of observations, the ratio in question will be comparable to one or to several thousands ; but it will not be the same where the first sum is composed of uneven powers, and that their changes of sign are considered. This circumstance will diminish this sum ; and the calculus shews that in the hy- pothesis of an equal probability of equal errors, plus or minus, the ratio of the sum of their uneven powers to the square root of the sum of the double powers, must be an inconsiperable fraction : we find, forexample, that there is one against one to wager that the observations are incompatible with this suppo- sition, when the ratio shall equal a fraction not differing much from | ; thus, in comparing the sum of the cubes of the errors to the square root of the sum of the sixth powers, or the sum of the fifth powers to the square root of the sum of the tenth powers, &c. when we find for one of these ratios a fraction which is not much below ■§■, that will suffice to shew the hypo- thesis in question to be improbable, and, consequently, that the observations ought to be rejected, as was stated above. In a great number of cases, and particularly in questions of 96 M. Poisson's Memoir on the astronomy, the quantity which it is proposed to determine by observations, is a given function of several elements which are already approximately known, and in which it is only necessary to make very small corrections, the products of which and all the powers higher than the first are neglected. The given function then becomes a linear function of these unknown cor- rections. It is made equal successively to all the values resulting from experiment, which affords as many equations of condition as there are observations. The employment of these linear equations for determining the corrections of the elements, by adopting for the purpose a great number of k ob- servations, has contributed much to the improvement of the astronomical tables. It appears that Euler and Mayer are the first who employed them ; one in his Memoir on the Perturba- tions of Saturn and Jupiter, which received the prize in 1750 from our academy, and the other in his Memoir on the Libration of the Moon. But their number being always superior to that of the unknown quantities, the solving of them occasioned some embarrassment, and this serious inconvenience ensued, that the calculators could deduce, from the same system of equa- tions, different results according to the method of calculation they employed. When there was only one unknown quantity to be determined, it was agreed to render its coefficient positive in all the equations that were subsequently added, to form the final equation, from which the value of the unknown quantity was to be deduced. When these unknown quantities were two or more in number, the combination of the equations of con- dition that was made to reduce them to an equal number of final equations was absolutely arbitrary. This embarrassment, and the inconvenience which resulted from it, remained to the period when M. Legendre proposed a direct and uniform me- thod of forming the final equations, which was generally adopted under the name of Method of least squares of the errors, which was assigned to it by its author. It consists, as is well known, in deducting from the result of each observation the linear function of which it furnishes an approximate value : the difference is the error of observation ; the sum of the squares of all these differences is taken : its differentials taken successively, with respect to the corrections of all the elements, Mean Results of Observations. 97 are there made equal to zero ; which gives as many equations as there are unknown quantities to be determined. This me- thod, if it possessed only the advantage of uniformity, and of freeing the steps of the calculation from all that is indetermi- nate, would be an important service rendered by our brother academician to the sciences of observation ; but it is also that which leaves the minimum of error to be apprehended in the value of each element, as Laplace has proved by the calculus of probabilities. Let us add, in conclusion, that after having calculated the corrections of the elements by the method of least squares, and having substituted their values in the linear expressions of the errors of the observations, if we take the sum of the uneven powers of all these errors, and divide it by the square root of the sum of their double powers, the magni- tude of the quotient will furnish a criterion, according to which observations should be rejected, or their results adopted, if they have, in other respects, a sufficient probability. On a Method of rendering Platina malleable. The Bakerian Lecture. By the late William Hyde Wollaston, M.D. F.R.S., &c. [From the Philosophical Transactions for 1829. Part I.] As, from long experience, I probably am better acquainted with the treatment of Platina, so as to render it perfectly mal- leable, than any other member of this Society, I will endea- vour to describe, as briefly as is consistent with perspicuity, the processes which I put in practice for this purpose, during a series of years, without seeing any occasion to wish for fur- ther improvement. The usual means of giving chemical purity to this metal, by solution in aqua regia and precipitation with sal ammoniac, are known to every chemist ; but I doubt whether sufficient care is usually taken to avoid dissolving the iridium contained in the ore, by due dilution of the solvent. In an account which I gave in the Philosophical Transactions for 1804, of a new metal, Rhodium, contained in crude platina, I have mentioned this precaution, but omitted to state to what degree the acids JULY— sept., 1829. H 98 Dr. Wollaston on a Method of should be diluted. I now therefore recommend, that to every measure of the strongest muriatic acid employed, there be added an equal measure of water ; and moreover, that the nitric acid used be what is called u single aquafortis ;" as well for the sake of obtaining a purer result, as of economy in the purchase of nitric acid. With regard to the proportions in which the acids are to be used, I may say, in round numbers, that muriatic acid, equi- valent to 150 marble, together with nitric acid equivalent to 40 marble, will take 100 of crude platina ; but in order to avoid waste of acid, and also to render the solution purer, there should be in the menstruum a redundance of 20 per cent, at least of the ore. The acids should be allowed to digest three or four days, with a heat which ought gradually to be raised. The solution, being then poured off, should be suffered to stand until a quantity of fine pulverulent ore of iridium, suspended in the liquid, has completely subsided ; and should then be mixed with 41 parts of sal ammoniac, dissolved in about five times their weight of water. The first precipitate, which will thus be obtained, will weigh about 165 parts, and will yield about 66 parts of pure platina. As the mother-liquor will still contain about 11 parts of platina, these, with some of the other metals yet held in solu- tion, are to be recovered, by precipitation from the liquor with clean bars of iron, and the precipitate is to be redissolved in a proportionate quantity of aqua regia, similar in its composi- tion to that above directed to be used : but in this case, before adding sal-ammoniac, about 1 part by measure of strong muriatic acid should be mixed with 32 parts by measure of the nitro-muriatic solution, to prevent any precipitation of palla- dium or lead along with the ammonio-muriate of platina. The yellow precipitate must be well washed, in order to free it from the various impurities which are known to be contained in the complicated ore in question ; and must ultimately be well pressed, in order to remove the last remnant of the wash- ings. It is next to be heated, with the utmost caution, in a black-lead pot, with so low a heat as just to expel the whole of the sal-ammoniac, and to occasion the particles of platina to cohere as little as possible ; for on this depends the ultimate ductility of the product. rendering Platina malleable. 99 The gray product of platina, when turned out of the cru- cible, if prepared with due caution, will be found lightly co- herent, and must then be rubbed between the hands of the operator, in order to procure, by the gentlest means, as much as can possibly be so obtained of metallic powder, so fine as to pass through a fine lawn sieve. The coarser parts are then to be ground in a wooden bowl with a wooden pestle, but on no account with any harder material, capable of burnishing the particles of platina* ; since every degree of burnishing will prevent the particles from cohering in the further stages of the process. Since the whole will require to be well washed in clean water, the operator, in the later stages of grinding, will find his work much facilitated by the addition of water, in order to remove the finer portions, as soon as they are sufficiently reduced to be suspended in it. Those who would view this subject scientifically should here consider, that as platina cannot be fused by the utmost heat of our furnaces, and consequently cannot be freed, like other metals, from its impurities, during igneous fusion, by fluxes, nor be rendered homogeneous by liquefaction, the mechanical diffusion through water should here be made to answer, as far as may be, the purposes of melting ; in allowing earthy matters to come to the surface by their superior lightness, and in making the solvent powers of water effect, as far as possible, the purifying powers of borax and other fluxes in removing soluble oxides. By repeated washing, shaking, and decanting, the finer parts of the gray powder of platina may be obtained as pure f as * The following experiment will prove the necessity of attending to this precaution : — if a wire of platina be divided with a sharp tool in a slant- ing direction, and, being then heated to redness, be struck upon an anvil with a hammer, so as to force into contact the two newly-divided sur- faces, they will become firmly welded together ; but if the surfaces have previously been burnished with any hard substance, the welding will be effected, if at all, with very great difficulty. When the powder of platina has been over-heated in decomposing the ammonio- muriate, or has been burnished in the grinding, I have in vain endeavoured to give it a welding surface, by steeping it in a solution of sal-ammoniac in nitric acid. t Sulphuric acid, digested upon the gray powder of platina, thus pu- rified, extracted less than j^ th part of iron. H2 100 Dr. Wollaston on a Method of other metals are rendered by the various processes of ordinary metallurgy; and, if now poured over, and allowed to subside in a clean basin, a uniform mud or pulp will be obtained, ready for the further process of casting. The mould which I have used for casting is a brass barrel, 6J inches long, turned rather taper within, with a view to faci- litate the extraction of the ingot to be formed, being 1.12 inches in diameter at top, and 1.23 inches at a quarter of an inch from the bottom, and plugged at its larger extremity with a stopper of steel, that enters the barrel to the depth of a quarter of an inch. The inside of the mould being now well greased with a little lard, and the stopper being fitted tight into the barrel by surrounding it with blotting-paper, (for the paper facilitates the extraction of the stopper, and allows the escape of water during compression,) the barrel is to be set upright in a jug of water, and is itself to be filled with that fluid. It is next to be filled quite full with the mud of platina ; which, subsiding to the bottom of the water, is sure to fill the barrel without cavities, and with uniformity, — a uniformity to be ren- dered perfect by subsequent pressure. In order, however, to guard effectually against cavities, the barrel may be weighed after filling it, and the actual weight of its contents being thus ascertained, may be compared with that weight of platina and water which it is known by estimate that the barrel ought to contain*. A circular piece of soft paper first, and then of woollen cloth, being laid upon the surface, allow the water to pass, during partial compression by the force of the hand with a wooden plug. A circular plate of copper is then placed upon the top, and thus sufficient consistency is given to the * From the mean weight of the ingots obtained in previous operations, it is known that the barrel described in the text ought to contain 16 ounces troy of dry platina powder. The weight of the contents of the , , ,. sp. grav. of platina — 1 ,, barrel = 16 ounces x -±-~^ h—TT- + the weight of a cubic sp. grav. of platina ° inch of water x capacity of the barrel in cubic inches = 1 6 ounces x — '■ — 21.25 + .526 ounces x 7.05 = 18.9575 ounces troy. Should the contents of the barrel weigh materially less than this estimated weight, there must be a want of uniformity in the disposition of the powder within the barrel. rendering Platina malleable. 101 contents to allow of the barrel being laid horizontally in a forcible press. The press which I have generally used for this purpose consists of a flat iron bar AB, set edgeways, and screwed down by a hook E, near its middle, where it would other- wise be liable to bend, to a strong wooden bench CD. The bar is connected by a pivot at its extremity A, with the lever AFG. An iron rod F H, which turns at its two extremities upon the pivots F and H, proceeds from the lever at F^ and, as the lever descends, propels forward the carriage I, which slides along the bar. A stopper or block being placed in the vacant space I k, the carriage communicates motion to the cradle klm, which is also made to slide along the bar, and carries the barrel N, which lies upon the cradle, straight against the piston O, which rests by its end against P, a pro- jection in the further extremity of the bar. The weight, which in this machine, when the angle of the lever's elevation is small, will keep the power, applied ver- tically at the extremity of the lever, in equilibrio = that power x . _ r k ~ — =77^- X cotan of the angle of the lever's AF [AF + FHJ elevation ; which expression, in the case of the press actually used, becomes, Power x 5. cotan of the angle of the lever's 102 Dr. Wollaston on a Method of elevation. This expression, at an elevation of 5°, becomes nearly 60 x power, and at an elevation of 1°, becomes nearly 300 x power; and when the lever becomes horizontal, the multiplier of the power becomes quasi infinite. This expla- nation will be sufficient to show the mechanical advantage with which, by means of this press, the weight of the operator, acting on the end of the lever, will be made to bear against the area of the section of the barrel, a circle little more than an inch in diameter. After compression, which is to be carried to the utmost limit possible, the stopper at the extremity being taken out, the cake of platina will easily be removed, owing to the conical form of the barrel ; and being now so hard and firm that it may be handled without danger of breaking, it is to be placed upon a charcoal fire, and there heated to redness, in order to drive off moisture, burn off grease, and give to it a firmer degree of cohesion. The cake is next to be heated in a wind -furnace ; and for this purpose is to be raised upon an earthen stand about 2\ inches above the grate of the furnace, the stand being strown over with a layer of clean quartzose sand, on which the cake is to be placed, standing upright on one of its ends. It is then to be covered with an inverted cylindrical pot, of the most refractory crucible ware, resting at its open end upon the layer of sand ; and care is to be taken that the sides of the pot do not touch the cake. To prevent the blistering of the platina by heat, which is the usual defect of this metal in its manufactured state, it is essen- tial to expose the cake to the most intense heat that a wind- furnace can be made to receive, more intense than the platina can well be required to bear under any subsequent treatment; so that all impurities may be totally driven off, which any lower temperature might otherwise render volatile. The fur- nace is to be fed with Staffordshire coke, and the action of the fire is to be continued for about twenty minutes from the time of lighting it, a breathing heat being maintained during the last four or five minutes. The cake is now to be removed from the furnace, and being placed upright upon an anvil, is to be struck, while hot, on the rendering Platina malleable. 103 top, with a heavy hammer, so as at one heating effectually to close the metal If in this process of forging, the cylinder should become bent, it should on no account be hammered on the side, by which treatment it would be cracked irremediably; but must be straightened by blows upon the extremities, dex- terously directed, so as to reduce to a straight line the parts which project. The work of the operator is now so far complete, that the ingot of platina may be reduced, by the processes of heating and forging, like that of any other metal, to any form that may be required. After forging, the ingot is to be cleaned from the ferruginous scales which its surface is apt to contract in the fire, by smearing over its surface with a moistened mix- ture of equal parts by measure of crystallized borax and common salt of tartar, which, when in fusion, is a ready solvent of such impurities*, and then exposing it, upon a platina tray, under an inverted pot, to the heat of a wind-furnace. The ingot, on being taken out of the furnace, is immediately to be plunged into dilute sulphuric acid, which in the course of a few hours will entirely dissolve the flux adhering to the surface. The ingot may then be flattened into leaf, drawn into wire, or submitted to any of the processes of which the most ductile metals are capable. The perfection of the methods above described, for giving to platina complete malleability, will best be estimated by comparing the metal thus obtained, in respect of its specific gravity, with platina, which has undergone complete fusion ; and by comparing it, in respect of its tenacity, with other metals possessing that quality in the greatest perfection. * The chemist will find this flux very serviceable for removing from his crucible or other vessels of platina those ferruginous scales with which, after long use, and particularly after being strongly heated in a coal or coke fire, they become incrusted. In the analysis of earthy mi- nerals, I have been in the habit of using a similar flux, composed of two parts by weight of crystallized carbonate of soda, and one of crystallized borax, well ground together. It has the advantage of not acting, like caustic alkali, upon the platina crucible, and is a powerful solvent of jargon and many other minerals, which yield with difficulty to other fluxes. If the mineral to be operated on requires oxidation, in order to decompose it, a little nitre or nitrate of soda may be added. 104 Dr. Wollaston on a Method of The specific gravity of platina, drawn into fine wire, from a button which had been completely fused by the late Dr. E. D. Clarke, with an oxy-hydrogen blowpipe, I found to be 21.16. The aggregate specific gravity of the cake of metallic mud, when first introduced into the barrel, exclusively of moisture, is about 4.3 ; when taken from the press, is about 10. That of the cake fully contracted, on being taken out of the wind-furnace before forging, is from 17 to 17.7. The mean specific gravity of the platina, after forging, is about 21.25, although that of some rods, after being drawn, is 21.4 : but that of fine platina wire, determined by comparing the weight of a given length of it with the weight of an equal length of gold wire drawn through the same hole, I find to be 21.5, which is the maximum specific gravity that we can well expect to be given to platina. The mean tenacity, determined by the weights required to break them, of two fine platina wires, the one of -j-Jq-q, the other of y^Vff of an inch in diameter, reduced to the standard of a wire -j^th of an inch in diameter, 1 found to be 409 pounds ; and the mean tenacity of eleven wires, beginning with ^oo anc * ending with ^.^o of an inch, reduced to the former standard, I found to be 589 pounds ; the maximum of these eleven cases being 645 pounds, and the minimum 480 pounds. The coarsest and the finest wire which I tried pre- sent exceptions, since a wire of T3 ^ of an inch gave 290 pounds, and a wire of g-Tr.&Tnr of an inch, 190 pounds. If we take 590 pounds, as determined by the eleven consecutive trials, to be the measure of the tenacity of the platina prepared by the processes above described, and consider that the tenacity of gold wire, reduced to the same standard, is about 500, and that of iron-wire 600, we shall have full reason to be satisfied with the processes detailed in the present paper, by which pla- tina has been rendered malleable. To this paper I beg to subjoin an account of some processes relating to two of the metals which are found in the ore of platina. To obtain malleable palladium, the residuum obtained from burning the prussiate of that metal is to be combined with rendering Platina malleable. 105 sulphur, and each cake of the sulphuret, after being fused, is to be finally purified by cupellation, in an open crucible, with borax and a little nitre. The sulphuret is then to be roasted, at a low red heat, on a flat brick, and pressed, when reduced to a pasty consistence, into a square or oblong and perfectly flat cake. It is again to be roasted very patiently, at a low red heat, until it becomes spongy on the surface. During this process, sulphur flies off in the state of sulphurous acid, espe- cially at those moments when the heat is allowed occasionally to subside. The ingot is then to be cooled ; and when quite cold, is to be tapped with a light hammer, in order to condense and beat down the spongy excrescences on its surface. The alternate roastings and tappings (or gentle hammerings) re- quire the utmost patience and perseverance, before the cake can be brought to bear hard blows ; but it may, by these means, at length be made so flat and square, as to bear being passed through the Halting-mill, and so laminated to any required degree of thinness. Thus prepared, it is always brittle, while hot, possibly from its still containing a small remnant of sulphur. I have also fused some palladium per se, without using sulphur ; but I have always found it, when treated in this way, so hard and difficult to manage, that I greatly prefer the former process. To obtain the oxide of osmium in a pure, solid, and crys- tallized state, I grind together, and introduce, when ground, into a cold crucible, 3 parts by weight of the pulverulent ore of iridium, and 1 part of nitre. The crucible is to be heated to a good red in an open fire, until the ingredients are reduced to a pasty state, when osmic fumes will be found to arise from it. The soluble parts of the mixture are then to be dis- solved in the smallest quantity of water necessary for the pur- pose, and the liquor thus obtained is to be mixed, in a retort, with so much sulphuric acid, diluted with its weight of water, as is equivalent to the potash contained in the nitre employed ; but no inconvenience will result from using an excess of sul- phuric acid. By distilling rapidly into a clean receiver, for so long a time as the osmic fumes continue to come over, the oxide will be collected in the form of a white crust on the 106 Sig. Santini on Achromatic Telescopes. sides of the receiver ; and there melting, it will run down in drops beneath the watery solution, forming a fluid flattened globule at the bottom. When the receiver has become quite cold, the oxide will become solid and crystallize. One such operation has yielded thirty grains of the crystallized oxide, besides a strong aqueous solution of it. On Achromatic Telescopes. By Signor G. Santini, Director of the Observatory at Padua. Since the publication of my theory of optical instruments, Mr. Rogers has read to the Astronomical Society of London, a Memoir, which appears to be of the highest interest for optical science, but with which I am unacquainted, except by an extract inserted in vol. v. of a periodical work published at Vienna, by MM. Ettingshausen and Baumgartner, entitled " Zeitschrift fur Physik und Mathematik," p. 120. Mr. Rogers, considering that the principal obstacle to constructing achromatic object-glasses for large refractors, is the difficulty of obtaining large pieces of pure homogeneous flint-glass, free from striae, and thus fit, by being combined with another lens of crown glass, to produce at once an achromatic lens, has en- tertained the happy idea of interposing between the lens of crown glass and its focus, when the pencil of luminous rays is much contracted, a correcting lens composed of two smaller lenses of crown and of flint glass, brought into contact, which, retarding the convergence of the red rays, and removing further off that of the violet rays, produces, in the rays of mean re- frangibility, the effect of a plane glass ; and it is clear that correct images will be produced, if the surfaces of the correct- ing lens and the distance from the greater object lens be so arranged, that all the heterogeneous rays parallel to the axis be united in the mean focus of this last. The eminent author lays down a simple rule for determining the focal distances of the correcting lenses ; and then observes, that if these be con- structed, nearly according to the dimensions laid down in the rule, the remaining chromatic errrors may be destroyed by means of a micrometrical motion, by which the two smaller Sig. Santini on Achromatic Telescopes. 107 lenses conjointly can be brought nearer or removed from the first ; and the errors arising from the figure will be destroyed by a small motion tending to separate in a small degree the two correcting lenses, without its being necessary, as in the ordinary theory, to retouch the surface of the last lens. The simplicity of this construction made me curious to cal- culate numerically the dimensions assigned by theory, so as to verify the simple method which is given for destroying the remaining chromatic and spherical aberrations. Having, in this last particular, obtained results which do not exactly agree with the statements of the illustrious author, I have brought them together here, with the results of my calculation, from which it will more clearly appear, under what circumstances, and with what precautions, recourse must be had to the pro- jected correcting lens. Imagine a system of three lenses placed in the same axis, and constructed of crown and flint glass, the indices of mean refraction of which are respectively m, m! ; the first and the second being of crown glass and convex ; the third of flint and concave. Let their focal lengths be p, q, r, and p = 1 ; also, let the distances of the points of union of the rays be indicated respectively by a, a ; 6, /3 ; c, y ; the distance of the first from the second lens = d ; let the second and the third be imagined in contact. As the correcting lens should produce in the rays of mean refrangibility the effect of a plane glass, q + r will be = 0, that is, q = — r. Now, considering that the rays parallel to the axis, a case which takes place in the object- glasses designed for astronomical observations, will be a — oo, a zrp = 1, 6 = — (I — d)\ and assuming, for the sake of brevity, t = -t — ♦ —, — 7' the equation, which should exist to 1 * a m m' - 1 destroy the longitudinal aberration of refrangibility, will be 1 + — (I-?) = ; from whence q = 6* (£ - 1) ; r = — b* (£ — 1); whence d and b being assumed arbitrarily, the focal distances of the two correcting lenses will be obtained, from which the rule laid down by Mr. Rogers evidently fol- lows, b, q, r, being obtained, the other distances /S, c, 7, are 108 Sig. Santini on Achromatic Telescopes. readily ascertained, since /3 =j—^-> and the last lenses being in contact, c will be = — /3, and since r = - q, y will = - 6. The figure of the lenses, such that the longitudinal spherical aberra- tion may be destroyed, remains to be determined. For this purpose, let X, X', x", denote arbitrary numbers, on which their figure depends \ and, for brevity (as in my Teoria degli Stro- menti Ottici, vol. i. No. 104), let ^ = Q , m ^™ ~ l \ ox n . ^ 8 (m — 1)8 (m +2) — 4 ( m "" - 1 ? 4 ~f m - 2 ms m (2 m + 1) V ~ 4 m ~ i ,P ~~ 2 ( m + 2 ) (™-i)' ' ~"2(w + 2) (m-1)' ; /x',v', f ', <7',t', denoting similar functions 2 (m + 2) (m-1) when the index m relative to the crown glass changes into the index m f relative to the flint. The proper reductions being then made, it will be found that the equation given in No. 108 of the above cited work, in order that the longitudinal spherical aberration in a system of three lenses may be de- stroyed, is brought, in the present case, to the following : — b* b 3 v* * + m O *$r t m V9 + — O v-V *') = (a), in which are the three arbitrary quantities, X, x', X"; two of them, however, being determined at will, the third follows; when, from the well known principles of optics, the rays for each of the surfaces of the lenses will be obtained. NUMERICAL EXAMPLE. To construct an achromatic object glass, from the foregoing principles, with crown and flint glass of Frauenhofer's ma- nufacture, of which the following are the indices : — For the crown mean rays m = 1. 5300001 , „ red rays m — dm — 1.521000] For the flint mean rays m f = 1.634494 1 , , _ A _ „„■ ' j i j r i ^i^^a^ \dm ' = 0.017787 „ red rays m'-dm' = 1.616707 J From which we get £ = 1.650853. Having assumed d = f ; b will be = - $, from whence q = 0.072317, r = - 0.072317, jS = - c = + 0.0594247, y = - b = 0.3333333. With respect to the figure of the lenses, two of the three quantities, X, X', X", remaining arbitrary, we shall determine X, X', so that the first Sig. Santini on Achromatic Telescopes. 109 two lenses shall be isosceles, which will be done by means of the following equations (No. 106, vol. i.) : — From these, in the present case, we shall obtain X= 1.G000676, X'=2.233782 • from whence equution(a) will give x"= 2.9 17899. According to these numbers, the radii of the lenses will come out as follows : — 1st lens, R = R l = 1.06. 2d lens, R" = R m = 0.0766555 ; double convex. 3d lens, of flint glass, double concave: R iv = -0.0800292, R v = — 0.1075404. The aperture should be determined so that that of the cor- recting lenses does not exceed the half of their focal length. The aperture of the first lens will thus be about = 0.108 : in round numbers = 0.1, which exceeds remarkably what is adopted in practice for the larger object-glasses. Let us now see, first, how in this system the chromatic aber- ration is destroyed for the rays nearest to the axis ; wherefore let us assign for the first lens 0.002 ; for the second, 0.002 ; for the third, 0.001 ; and let k, h\ *», fc iU , k iv , /c v represent the distances at which the rays nearest the axis unite after refrac- tion at the first, second . . . sixth surface. From the prin- ciples of dioptrics we shall find, For the mean rays. For the red rays. k = 3.060000 k™ = 0.0589577 k = 3.094550 A 5ii = 0.0603419 A 1 = 0.999673 A iv = 0.1809460 A 1 = 1.016946 k™ = 0.1823450 A 11 = 0.1542802 A* = 3.14150 A» = 0.1575919 ft* = 0.314422 So the remaining chromatic aberration will be = 0.000272. Before proceeding to calculate the spherical aberration, it is as well to destroy this remaining aberration by a Small variation S d given to the distance d. Calling £ k v the correspondent variation of Ar v , there will be found £ k r = — r n ,x - 2 $ d ; wherefore we shall have, For the mean rays, A* = 0.314150 — 0.889959 Id For the red rays, h? = 0.314422 — 0.805748 I d Making these two values of k y equal to each other, there will 110 Sig. Santini on Achromatic Telescopes. be ) d = — 0.003230 ; wherefore d = 0.663437. Recalcu- lating the values of k by this corrected value of d, we obtain the following results : — Mean rays. Red rays. k = 3.060000 A Ui = 0.0590609 k = 3.094550 A Ui = 0.0603006 A» = 0.999673 A* = 0.1815420 ft = 1.016946 k" = 0.1828973 A" = 0.1547307 h? = 0.317137 A u = 0.1580190 A* = 0.317921* Remaining aberration = 3.000016 from which it results that the remaining chromatic aberration may be neglected. For the purpose of determining the spherical aberration which takes place in this system of lenses, with the superior distance d corrected, we shall denote the angles of incidence of a luminous ray which goes toward the extremity of the first lens in successively refracting surfaces, by i, i\ if* • • i v ; the re- fracted angles respectively by /, l'\ l' 1 ' 1 •• l v ; the inclinations of the directions of the refracted ray to the axis, by o, o\ o u -« o v ; the distances of the point of meeting from the respective re- fracting surfaces by k, k\ & u -«& v . Then retaining the above quantities for the size of the lenses, and in round numbers regarding i = 2° 43', we shall find, For the mean rays. / // o / // i — 2 43 0.0 o 1 = 2 53 7.96 I = 1 46 30.8 A» = 0.995676 o = 56 29.2 i» =9 39 45.36 A = 3.0585405 Jl = 6 17 53.35 t> = 3 38 30.40 o u = 6 14 59.77 = 5 36 9.16 A u = 0.1539007 Z'iii - 18 56 27.6 iv = 5 14 45.7 m = 29 46 38.1 A iv F 0.1813396 o Ui = 17 5 10.3 V> =3 32 54.9 m* 0.0529159 /v = 5 48 23.0 i* = 29 12 51.8 ov = 2 59 17.6 I* = 17 oo 27.2 Av = 0.316238 For the red rays. o / // o / // i = 2 43 0.0 o» = 2 50 11.3 I = 1 47 8.6 A 1 = 1.012955 * .This should be .317121.— Ed. Sig. Santini on Achromatic Telescopes. Ill For the red rays • o / // o / // o = 55 51.4 t» = 10 8 43.80 A = 3.0930420 /» = 6 39 1.45 t> = 3 38 52.63 o» = 6 19 53.65 fi = 5 33 12.53 A» = 0.1571542 a»i =19 28 52.3 o lv = 2 23 30.0 f u = 50 28 50.9* AIT = 0.1825478 0*"= 17 19 51.2 i* = 3 42 26.3 A m = 0.0538743 P = 6 1.9 t lT = 29 53 44.8 o* = 3 5 54.4 F = 17 57 23.6 A* = 0.315527 For the mean rays nearest to the axis k v is a 0.317137, which, compared with the above value of k y for the remote mean rays, will give the remaining spherical aberration, = 0.000899 ; that is, about ten times greater than what writers on optics lay down as tolerable to the eye. Mr. Rogers extols, as one of the advantages of his new con- struction, the power of removing the spherical aberration by a slight separation of the second from the third lens, which is not to be defined, but to be performed by means of a micrometrical adjustment, until it is found by observation to be destroyed, or at least rendered unappreciable to the eye. Although it does not appear very commendable to allow a micrometrical motion to this system of lenses, from which may arise errors of cen- tering more dangerous than those it is sought to avoid, it does not appear to me possible, at least in this example, to remove, by this method, the spherical aberration. In fact, introducing a small distance I d! between the second lens and the third, the chromatic errors are reproduced which had been pre- viously destroyed. We must, therefore, on this account, make the distance d vary contemporaneously by a small arbitrary quantity, £ d : calculating numerically the coefficients of £ d, $ d' in the expression of A: v , as well for the proximate as the remote rays, I obtain the following results : — For the nearest mean rays, k 1 = 0.317137 ■— 0.88962 Id — 28.8332 3 d! For the nearest red rays, A' = 0.317121 — 0.80472 >d — 27.5364 W For the remote mean rays, A* = 0.316238 — 1. 21610 St/ — 34.8746 \d' * So in the original, but this evidently should be 30° 28' 50.9".— Ed. 112 Sig, Santini on Achromatic Telescopes. Making an equation between the values of /c v , we obtain $d = + 0.014013, Jd'= - 0.0009021 ; and the correcting lenses being previously supposed in contact, the negative result is inadmissible. I do not wish to deduce generally from this, that with no other ratio of dispersion the chromatic and spherical aberrations may not even this way be destroyed ; only it appears that they vary considerably with the distance £ d' ; so that, if even in other cases the thing be possible, the micrometrical ap- paratus should be constructed with the greatest care. Not having succeeded, by varying the distances, in destroy- ing the spherical aberration, I have had recourse to small arbitrary variations, d R iv , d R v , given to the rays of the last lens, which I have regarded as positive, although relative to a concave lens, having with greater facility obtained in this hypothesis the general equations relative to the path of a ray of light. In this way I have found the following equations of condition. Forthe nearest meanrays,Av = 0.317137 — 10.07444 dR iv — 5.51794 dR* For the nearest red rays, & T = 0.317121— 9.79024 c?R iv — 5.37508 dR» Forthe remote mean rays, £ v = 0.316238 — 12.15546 dR iT — 4.97661 rfRv The resolution of which gives d R iv = - 0.0002655; d R v = + 0.0006401 ; k v = 0.316280. From whence the corrected values of R iv , R v will be R iv = 0.0797637; R v = 0.1081805 ; the distance remaining d = 0.663437. If now the distance k v of the point in which the rays unite behind the last lens be directly calculated in this system, there will be found — For the mean rays nearest the axis, k v = 0.316145 For the red rays nearest the axis, k v = 0.316136 For the mean remote rays, k 9 = 0.316120 For the red remote rays, A* = 0.315466 Remaining aberrations. Chromatic in the mean rays, = 0.000009 Spherical in the mean rays, = 0.000025 Spherical in the red rays, = 0.000669 The first two remaining chromatic and spherical aberrations are extremely minute, and without the small errors from the tables to seven places of figures, or without the influence of the Sig. Santini on Achromatic Telescopes. 113 second powers of the corrections found, would have been eva- nescent; the last, that is the spherical aberration in the red rays, is about the same order as that which remains in the double object glasses, constructed according to the theories of Her- schel and Frauenhofer ; and therefore less than what remains in the triple object-glasses. It cannot be taken away altoge- ther, but may still be diminished, if it would be worth while to give up the simplicity of construction which lenses of equal curvature present, such as we have supposed the first and the second to be. But it is evident, at the same time, that the aber- rations vary considerably with the rays of the last lens ; and hence the construction of a correcting lens of this sort requires great care, and should not be recommended, except for the greater telescopes designed for astronomical observations, for which they may be employed with great advantage and saving of expense. Another great advantage from the construction of Mr. Rogers is, the field being free from a coloured edge. In fact, the condition that should have place in a system of three lenses separated by the distances d, d' } and disposed round the same axis, that the coloured margin should be removed, is represented by the equation (Vol. ii. No. 246) o £, which in this case is identical, since d' = 0; q+r=0. Such a combination, moreover, deserves all the attention of practical opticians. Giovanni Santini. Travels in Turkey, Egypt, Nubia, and Palestine, fyc, in 1824, 5, 6, and 7. Byll. R. Madden, Esq., M.R.C.S. 2 vols. London, 1829. At a moment when political events, of a magnitude scarcely to be estimated, are rivetting the attention of the world upon Turkey and Turkish interests, comes forward this, among other works, calculated to satisfy the literary craving which such a state of things is sure to engender. But, independent of the interest which Mr. Madden's work possesses from the peculiar circumstances of the times, it is well worthy of atten- tion from the curious and obviously faithful picture which it JUNE — sept., 1829. I 114 Madderfs Travels in Turkey, $-c. presents of the condition of mankind in that extensive region which owns the sway of the Grand Signior. The author en- gages in the task with no ordinary claims upon our confidence. His was no rapid survey of a country, taken with pen in hand, where impressions are noted down as they first arise, un- checked and uncorrected — where much is trusted to second- hand information — where matters are treated of, foreign to the author's usual habits of observation and thinking. We have, in the instance before us, a gentleman, bred to the profession of physic, and though not yet possessed of its highest honours, well skilled in the knowledge which entitles him to them, so- journing for four years in the country which he professes to describe, with an ardent love of information, a good under- standing, an unprejudiced judgment, and abundant opportuni- ties of exercising all his faculties of observation and research. Such a man can hardly have failed of producing a book cre- ditable at least to himself, and useful to others ; but Mr. Madden's volumes have the additional merit of a high degree of literary polish. His style is easy and flowing. His graver reflections on literature and science are pleasingly mixed up with playful anecdotes, descriptions of scenery, and the little incidents of his own journey. It is impossible to read the work without feeling an interest for its author. His accuracy is unquestionable. His good humour never deserts him. This is all for which he takes credit. Apologizing, with much mo- desty, for his literary qualifications ; acknowledging that he did not carry in his head Herodotus and Hamilton, Pococke and Pausanias, affecting not to be a learned traveller, he lays claim only to some share of patience and philosophy. An unruffled temper and a cheerful demeanour he has found to be the best passports to Turkish confidence. A mild manner and quiet deportment will, he says, carry a traveller through difficulties, which peevishness and pride (the too frequent qualities of an English traveller) would have rendered intolerable. The fero- city and fanaticism of the most obstinate Turk may be subdued, as it would appear, by good humour. The volumes before us contain a vast fund of information respecting the present political and social condition of the inhabitants of the various provinces of Turkey, — .European, Asiatic, and African. These, however, we do not propose to analyse at present. An ample field of observation remains in the medical and philosophical parts of Mr. Madden's travels. As a medical man, Mr. Madden had ample opportunities of ascertaining the state of literature, and more especially of me- Madden's Travels in Turkey, fyc. 115 dicine, in the countries through which he travelled, and he appears to have availed himself of them most fully. It shall be our object to lay before the reader the substance of the author's observations on these important topics, following, however, our own arrangement of the matter. It may be pro- per to premise, that Mr. Madden's Travels are written in the form of letters to his principal friends, whom he addresses on the subjects adapted to their respective capacities. His female acquaintances are entertained with the description of a Turkish toilette, and an occasional poetical effusion. The Reverend Mr. M'Pherson receives copious details concerning the Route of the Israelites, and the passage of the Red Sea. A letter to Thomas Coltman, Esq., barrister, affords the opportunity of describing the state of Turkish law, and its formidable ad- juncts, the sack, the bowstring, and the bastinado ; while his medical friends, Dr. James Johnson, Dr. Gregory, and Mr. Joshua Brookes are favoured with accounts of vapour-baths, amulets, and madjouns, the dysentery, the ague, and many such plagues and pestilences. The volumes teem with accounts of the low condition to which medical science is reduced throughout Turkey ; and such probably it was throughout all Europe not many centuries back. It has been well remarked, that the state of medicine may be considered as the criterion or barometer of the state of science in any country. Wherever science and refinement have extended their influence, there will medicine be most cherished, as being so eminently conducive to the interests and happiness of mankind. The following lively sketch of the mode of conducting business at Constantinople will illustrate this remark : — " There are about fifty medical practitioners in Constantinople, principally Franks, from Italy and Malta, and a few Ionian Greeks, Armenians, and Copts ; of this number there are, perhaps, five regularly educated physicians, and two of these are English gentle- men, highly respected, both by the Turks and Franks. Every medico has his allotted quarter ; he beats this ground daily in pur- suit of patients, and visits all the coffeehouses in the district with a Greek drogueman y as interpreter, at his heels, whose occupation it is to scent out sickness, and to extol the doctor. They are ever to be found on the most public bench of the coffeeshop, smoking with profound gravity, and prying into the features of those around them, for a symptom of disease. I confess I had to descend to this degradation, to get practice, in order to become acquainted with the domestic customs of the people. The first day my drogue- man, whc had just left the service of a Roman doctor, and had been practising on his own account since his discharge (for all I 2 116 Madden* s Travels in Turkey, 8fc. droguemen become doctors), took upon him to teach me my pro- fessional duty, which he made to consist, in never giving advice before I got my fee, in never asking questions of the sick, and in never giving intelligible answers to the friends ; I was to look for symptoms only in the pulse ; I was to limit my prognosis to three words, ' In Shallah,' or, ' Please the Lord,' for doubtful cases ; and ' AUakharim,' or ' God is great/ for desperate ones. I took my post in the coffeeshop, had my pipe and coffee, while my drogueman entered into conversation with the Turks about us." — Vol i. p. 54. The story then proceeds as follows : — " A well-dressed man, who had been sitting by my side, in silence, for half an hour, at last recollected he had a wife or two unwell, and very gravely asked ' what I would cure a sick woman for ?' I inquired her malady, — ' she was sick.' In what manner she was affected, — ' why, she could not eat.' On these premises I was to undertake to cure a patient, who, for aught I knew, might be at that moment in articulo mortis. I could not bring myself to drive the bargain ; so I left my enraged drogueman to go through that pleasing process. I heard him ask a hundred piastres, and heard him swear, by his father's head and his mother's soul, that I never took less : however, after nearly an hour's haggling, I saw fifty put into his hand ; and the promise of a hundred more, when the patient got well, I saw treated with the contempt which, in point of fact, it deserved. No man makes larger promises than a Turk in sickness, and no man is so regardless of them in con- valescence. I visited my patient, whom I afterwards found both old and ugly ; but I was doomed, on the first occasion, to see no part of her form ; she insisted on my ascertaining her disease with a door between us, she being in one room and I in another ; the door was ajar, and her head, enveloped in a sheet, as it was occa- sionally projected to answer me, was the only part of her I had a glimpse of; this was the only woman I ever attended here or in the islands, who would not suffer the profanation of my fingers on her wrist. I, however, could just collect enough from the attendants, to cause me to suspect she had a cancer ; and I did all, under such circumstances, that I could well do — I gave her an opiate." — pp. 57, 58. At page 59 is a well told story of a Turkish consultation, at which the author assisted. Nothing can display more clearly the miserable condition of the medical interest in Turkey than this scene. A host of doctors, Jews, Greeks, Italians^ and even Moslems, thronged round the sick man's bed. Amongst them were jumbled the friends, slaves, and followers of the poor patient. The latter gave their opinion as well as the doctors. But he who took the leading share in the business of the day, was a Turkish priest, who administered to the diseases MadderTs Travels in Turkey, #c. 117 both of soul and body. After a most unintelligible exordium, oil of wax was proposed, and agreed to. The doctors got their fee, (four Spanish dollars each, the only rational part of the story,) and the patient soon afterwards died. The secret of the Turkish priest's activity then came out. The bulk of the patient's property was invested in a mosque. The faith of Turks in the power of amulets, fertilizing potions, and madjouns, seems to be universal. Indeed, from what we learn in these volumes, the principal business of the doctor is the prescribing of these efficacious remedies. " There are few Mahometans," says the author, page 63, " who do not put faith in amulets. I have found them on broken bones, on aching heads, and sometimes over love-sick hearts. The latter are worn by young ladies, and consist of a leaf or two of the hyacinth. Sometimes these amulets consist of unmeaning words, at other times of a scroll, bearing the words, \ Bismii- lah,' * in the name of the "most merciful God,' with some ca- balistic sign ; but most commonly they contain a verse of the Koran. In dangerous diseases recourse is had to the most potent of all charms, shreds of the clothing of the pilgrim- camel which conveys the Sultan's annual present to the sacred city. The amulet in most common use is an amber bead, with a triangular scroll worn over the forehead. This is probably an imitation of the phylacteries which the Jews were com- manded c to bind for a sign upon their hands, and to be as frontlets between their eyes.' " They are manufactured by Ma- rabouts and Arab sheiks. Some very preposterous applica- tions of a similar kind are occasionally to be seen, such as a roasted mouse laid upon a gun-shot wound, and intended to extract the ball. These absurdities, it may be said, only indi- cate the low state of intellect in the mass of the Turkish popu- lation, but it may reasonably be doubted whether the sick would be better off in the hands of the faculty. Ladies were incessant in their demands upon the Doctor for some potion that would ensure fertility. A woman in Turkey has no honour or respect until she prove a mother, and all there- fore are desirous of a progeny like Priam's. In spite of the specifics, however, they have in general but few children, for polygamy is undoubtedly injurious to population. But great as is the fondness of the women for medicines to make them fruitful, it is exceeded by that of the men for aphrodisiacs, which they denominate madjoun. The author was solicited for them in every province of the empire which he visited. It is lamentable to think that hardly a man arrives at the age of five and thirty whom debauchery has not debilitated and made 118 Madden's Travels in Turkey, See. dependent for his pleasures upon this sort of adventitious ex- citement. The common rnadjoun of Constantinople is com- posed of the pistils of the flower of the hemp plant ground to powder, and mixed up in honey, with cloves, nutmeg, and saffron. Everyone has heard of the opium-eaters in Turkey, and the author was naturally anxious to inform himself concerning this supposed fascinating practice. The coffee-houses where the Theriakis, or opium-eaters, assemble are situated in a large square, near the mosque of Soly mania, and on a bench outside the door, they await the wished for reve- ries. There the author stationed himself to watch the effects of the potent drug. The gestures of the men were frightful. Those who were completely under the influence of opium talked incoherently. Their features were flushed, their eyes had an unnatural brilliancy, and the expression of their countenances was horribly wild. The effect is usually produced in two hours. The dose varies from three grains to sixty ; one old man was seen by the author to take twenty-four grains in two hours. He had been in the habit of eating opium for five and twenty years. The effects of this practice are painted by the author in the most dismal colours. " The debility," he says, " both moral and physical, attendant upon it, is terrible. The appetite is destroyed ; every fibre in the body trembles ; the nerves of the neck become affected, and the muscles get rigid," producing wry necks and contracted fingers. Life itself, as we may well suppose, is shortened by it. A regular opium-eater seldom lives beyond thirty years of age, if he commence the practice early. The habit, however, is too agreeable to be easily aban- doned. The man is miserable till the hour arrives for taking his daily dose, but when its influence begins, he is all fire and animation. Some compose verses, and others harangue the bystanders, imagining themselves emperors, with all the harems in the world at their command. The following detail of the author's own feelings when in- toxicated by opium, is too curious to be omitted. It reminds us very strongly of the inhalation of the nitrous oxide which Sir H. Davy describes as producing a " thrilling, and a sense of tangible extension highly pleasing, in every joint." The dose which Mr. Madden took was four grains, shortly after which, he says — " My spirits became sensibly excited: the pleasure of the sensa- tion seemed to depend on a universal expansion of mind and matter. My faculties appeared enlarged : every thing I looked on seemed increased in volume ; I had no longer the same pleasure when I Madden's Travels in Turkey, fyc. 1 19 closed my eyes which I had when they were open ; it appeared to me as if it was only external objects, which were acted on by the imagination, and magnified into images of pleasure : in short, it was * the faint exquisite music of a dream' in a waking moment. I made my way home as fast as possible, dreading, at every step, that I should commit some extravagance. In walking, I was hardly sensible of my feet touching the ground. It seemed as if I slid along the street, impelled by some invisible agent, and that my blood was composed of some etherial fluid, which rendered my body lighter than air. I got to bed the moment I reached home. The most extraordinary visions of delight filled my brain all night. In the morning I rose, pale and dispirited ; my head ached ; my body was so debilitated that I was obliged to remain on the sofa all the day, dearly paying for my first essay at opium-eating." — Vol. i., p. 26. Early in the month of July, 1825, the author reached Alex- andria, where the first thing that attracted his notice was the climate of Egypt. His observations on this very interesting topic are somewhat desultory, but we shall extract their sub- stance for the benefit of our readers. From the 1st of May to the 20th of June an easterly wind blows, called the kamsin, or simoom. It is the poison wind of the desert, and its effects on animal life are oppressive in the extreme. It produces such languor and exhaustion as made the author often lie for hours on his divan, incapable of the slightest mental or bodily exertion. The sensation was inex- pressibly distressing. It was not, however, the degree of heat which occasioned it, for the thermometer is not affected more than five or six degrees during its prevalence. Perhaps some electrical condition of the air may be the real cause of this sin- gularly depressing influence upon the nervous system. The country, which has had no rain since March, is now completely parched up. The soil is split into innumerable cracks. The trees are scorched. The only plant that survives the drought is the alkaline salsola, which covers the burning sands. About St. John's day (the 24th of June) the face of nature changes. The north-west, or Etesian winds, begin to blow, and so continue till September, diffusing at Alexandria an agreeable freshness in the air. A heavy dew, called the nocta, falls also at this time. The drooping plants revive, and pestilence is stayed. Alexandria is at all times very damp. The atmosphere is saturated with a saline vapour, which con- denses on the walls and furniture of the houses, in small crys- tals of nitre, sal ammoniac, and common salt. The soil is every where coated with these saline particles, and every thing made of iron rusts. Yet is this saline atmosphere not injurious 120 Madden's Travels in Turkey, Sfc. to breathing : diseases of the lungs are unknown. Except during the prevalence of the Etesian gales, the sky of Egypt is serene and beautifully blue. All Egypt in the vicinity of the river is a lake, from the be- ginning of August to the end of October ; that is to say, the Nile then brings down all the moisture which the Etesian winds, loaded with clouds from the Mediterranean, had been carrying up since June. On the subsidence of the Nile, agri- culture commences. Early in January spring puts forth its buds, and in April the first harvest is ended. By a system of irrigation the country is made to afford a second harvest, which is reaped in August, prior to the overflow. At Alexandria the thermometer, during the summer months, seldom exceeds 90°, nor is the heat oppressive ; yet, owing to other causes, its climate is the most unwholesome in all Egypt. The principal of these is the vicinity of the Lake Mareotis, now a saline swamp. The quarter of the city nearest the lake is subject to intermittent fevers in the spring, and to malig- nant putrid fevers in the autumn. The climate of Upper Egypt is singularly dry, yet syca- mores, five or six hundred years old, have thriven there with- out a drop of rain, and some, which are highly situated, without even deriving moisture from the inundation. A sheet of paper may be exposed there all night without its imbibing a particle of moisture, the nocta extending only to Lower and Middle Egypt. In Alexandria, Damietta, and Rosetta, there is more or less rain from November till March^ and sometimes excessively cold weather ; but in Cairo, though only one hun- dred and fifty miles distant, there is much less of both. In Upper Egypt there is no rain for six or even ten years, but when it does come, it is in torrents. During the intense heat of summer many birds leave Egypt, while the swallows of Europe make it their abode in winter. Their last starting- place appears to be the Morea. A medical man travelling through Turkey must naturally hear much of the plague, but Mr. Madden did more : he saw a great deal of it, and studied the disease with a very proper degree of professional zeal, avoiding, we are happy to say, at the same time, those absurd attempts at bravado, which have cost some English physicians their lives, and others their cha- racter for common sense. One of the best chapters in Mr. Madden's first volume is that which he devotes to the subject of plague (Letter XVII. to Dr. Quin) ; and his opinions really appear to us so good, that it is but justice to bring them at Madden's Travels in Turkey, fyc. 121 some length before our readers. The author had some expe- rience of the plague, both at Constantinople and in Candia, but his notions of it were then confused, sometimes believing it to be contagious, sometimes infectious, and sometimes neither the one nor the other. On his arrival at Alexandria he found the disorder very rife ; the natives were perishing at the rate of eighteen per day, and few days passed over without the death of an European. " For so small a population as that of Alexandria, say sixteen thousand souls, the mortality was considerable : every house was shut up, the servants were not suffered to go out, money was passed through vinegar before it was touched, letters were smoked, papers were handled with tongs, passengers in the streets poked unwary strangers with their sticks, to avoid communication, people thronged round the doctors' shops to know how many died in the night: the plague was discussed at breakfast, contagion was described at din- ner, buboes and carbuncles (horrescoreferens !) were our themes at supper. The laws of infection were handled by young ladies in the drawing-room ; * a cat could communicate the plague, but a dog was less dangerous ; an ass was a pestiferous animal, but a horse was non-contagious. Fresh bread was highly susceptible, but butchers' meat was non-productive/ If you looked at a man, he felt his groin; if you complained of a headach, there was a general flight; if you went abroad with a sallow cheek, the people fled in all directions ; if you touched the skirt of a Christian's coat, you raised his choler : and if you talked of M'Lean, your intellect was suspected to be impaired." The author visited the plague hospital daily, sometimes taking with him his host, Mr. Casey, whose fears he had some- how contrived to overcome. " The pesthouse consists of several small rooms, with a grated window opposite the door facing the east, as if intended for receiv- ing the poisonous wind of the desert. There is neither chair nor table in this dungeon ; the sole furniture is a cane bed, called a cafass, with a mattress, and a sheet, which serves for a shroud a little later. The door is generally locked on the unhappy patient, an Arab attendant sits smoking his pipe outside, and very rarely enters to moisten the burning lips of the sufferer, or to lessen the terror of his solitary confinement ; once a day the Italian doctor enters the room ; orders a decoction of marshmallows, or elder- flower water, and then departs. Of all human horrors, earth has nothing to compare with the dismay depicted on the features of the sick, in these dreadful receptacles of pestilence ! We would have wished to spare our readers a medical descrip- tion of the plague, but the history which Mr. Madden gives of it, as occurring in his own servant, is so striking, and so illustra- 122 Madden's Travels in Turkey, tyc. tive of the common phenomena of the disease, that we cannot pass it over. He had taken his man with him to a supposed case of apoplexy ; it proved to be the plague. " The second day after this, I observed him staggering as he walked, his eyes had the expression of a drunken man's, his features were tumid, and yet he complained not ; 1 asked him in the even- ing if he felt unwell ? he said he .had a cold ; but I perceived he could hardly keep his feet : his pulse was very frequent, but easily compressed and not full, his tongue was of a whitish brown in the centre, with the borders very red. " I saw the poor fellow had the plague, and I took him to the hospital. When we arrived there I saw him shudder (and well he might) : he said to me, * Don't you recollect, sir, I said in the Bazaar, that health is above every thing ?' I never was more un- comfortable; I felt as if I was in some sort accessary to his disease. Headach and nausea distressed him from the time he was put to bed ; he shivered frequently, but he said * his heart was burning.' At night two livid spots were discovered on the forearm, with purple streaks, extending to the axilla and terminating in a bubo. His skin was parched and burning, his eye glaring on one object; and when his attention was called off, he talked incoherently, and com- plained of his tongue becoming swelled. His pulse at sunset was one hundred and eighteen, small and obstructed, his features swollen and of a sallow crimson hue ; but next morning his colour was of a darker purple, such as denoted congestion somewhere, strangling the circulation. His regard was constantly fixed on the ceiling, and the low thick muttering of his lips had been incessant during the night. At four o'clock he bounced out of bed, escaped unnoticed, passed the outer door of the hospital, and ran, naked as he was, several yards in the direction of his home ; but here he was overtaken by the people of the pesthouse ; he had just sunk down quite exhausted. The strength of death, which had carried him thus far, was now gone ; and, with the help of two Arabs, he was borne back to his dungeon, (for it deserved no better name,) trail- ing his feet, and his head sunk on his bosom. I saw him two hours after this ; the bubo was the size of a small orange, the two livid spots had become large carbuncles, his eyes were glazed, yet unnaturally brilliant, and his fingers were playing with the bed clothes ; at dusk the rattling of the throat was accompanied with spasms of the muscles of the neck ; these went off, and after a couple of hours, without any apparent suffering, he died." The author has his own speculations on the causes of plague, and upon the proper mode of managing it. These, we think, very rational and deserving of mature reflection. His notion is that the plague is essentially of endemial origin, in other words, that the original miasm is formed by some obscure pu- trefactive process, and that the atmosphere is only the medium Madden's Travels in Turkey , #c. 123 by which the poisonous matter, thus eliminated, reaches the human body. He goes a step further, however, than this. Common malaria he believes to be formed from the decompo- sition of vegetable matter contained in the soil. Plague miasma, again, originates in the putrefaction of animal mat- ter, the production of both depending on certain states of moisture and heat. But while the author is thus clear in at- tributing to plague an endemial origin, he is perfectly satisfied that it is also a contagious disorder, and that the contagious emanations from the bodies of the sick may produce the disease in others, in three different ways: — first, by contact; secondly, by means of the breath ; and thirdly, by woollen clothes and other fomites, which have become saturated with contami- nated air. The contagion of plague, according to Mr. Mad- den, requires to be in a certain state of intensity to produce the disorder in others. Hence it is, that with proper precau- tion, a pest hospital may be visited with impunity. " In a word, plague under all circumstances is contagious, but under some, far more so than under others. In a well-ventilated chamber, where the bed-clothes are shifted daily, where the floor is washed daily, and a fire kept constantly in the apartment {this I consider the most important agent of all in carrying off the foul air) there is hardly any peril in approaching the bedside of the sick, avoiding his breath, and suffering no part of one's dress to touch the bedclothes. At four feet from the bed of the plague patient, in an airy room, there is no danger whatever. The miasma, I have ascertained, by much observation, (so far as an invisible agent is amenable to observation or experience) does not extend beyond a very few feet from its source ; I would say, not four feet from the bedside, and then it becomes so diluted by the surrounding atmos- phere as to prove innoxious." From these statements it appears that the plague is, in the author's notion, more allied to typhus fever and to ague, than it is to small-pox and measles. It is held by the best physicians, that the two latter diseases are entirely the produce of vital actions, and that no combination of agents, exterior to the human frame, can give rise to them. The complete ex- emption of the world from these complaints for so many hun- dred years, and the fact that at St. Helena they are invariably imported, are decisive, we think, in favour of this doctrine. On this point then we are perfectly agreed with the author. But we have our doubts how far he is right in attributing the origin of plague so exclusively to animal decomposition. He strives to account for it thus : — In Turkish towns the butchers kill their meat in the public streets. The streets are never 124 Madden's Travels in Turkey, fyc. cleansed. Dead dogs, cats, and rats, are constantly putre- fying there. The carrion of camels and asses may be seen lying in the great thoroughfares. The Turks seldom change their linen, and in spite of their daily ablutions, are, in reality, a very dirty people. In every town of the Levant the Jewish quarter is the first affected by plague, and there every descrip- tion of animal putrefaction is, par excellence, going forward. We mast do the author the justice to say, however, that he does not overlook the facts that seem to associate the plague with some condition of the soil. " It ceases," he tells us (p. 283), " when the inundation is established, and begins when the lands have been drained." This he attempts to explain by saying that the atmosphere is thereby rendered a better recipient of the pestilential effluvia which have their origin else- where ; but we can hardly go along with him in this refine- ment. To all this theory, however, is appended the following very philosophical reflection : — " I am endeavouring to illustrate this scourge of the Levant by facts, for I disclaim all theories. In a science, like that of medicine, where there are no general rules, there can be no unerring- and universal principles ; and, above all, in an anomalous disease, like that of plague, he who soars into the clouds to analyze the float- ing particles of miasma; to search after the causes of the fomes, and not to study its effects ; to prove that the disease be infectious only, or contagious only ; taken only by the breath, or only by the touch ; to waste research and learning on mere terms ; cavilling about distinctions between endemics and epidemics, but never turning attention to the treatment of the disease ; that man, I say, may acquire notoriety, by the novelty or ingenuity of his theories, but he is not likely to lessen the mortality of the disorder." The opinions which the author has been led to entertain on the treatment of the plague may be summed up in a few words. He condemns bleeding, and all measures of depletion, whilst he places the highest confidence in strong stimulants, diffusible and permanent. Wine and brandy were his sheet anchors. These he gave from the first moment the patient came under his care, even though the eye was suffused, the cheek flushed, and the skin dry. The first day he gave his brandy and water, one-third spirit; the second day he made it half and half; on the third day he contented himself generally with keeping up the excitement by strong Cyprus wine. If the patient live to the sixth day, he is very likely to recover. The third is that of greatest danger. By this treatment (with some other items of minor importance) he saved, in Candia, five patients out of nine. Every thing, however, he allows, depends on early Madden's Travels in Turkey, Src. 125 treatment. So satisfied was he with his success at Candia, that on his arrival at Alexandria he proposed to attend plague patients for the season, and undertook to save from seventy to seventy-five per cent, of the sick. The measure, however, was never carried into effect ; and we suspect, had the author tried his plan upon a large scale, he would have been disappointed. We are quite ready to admit that the principle of his treatment is good, but the virulence and depressing influence of the poi- son is such as to bid defiance to all ordinary restoratives. Besides, the plan has been tried and failed. In the Ionian Islands, in 18 1G, the tonic plan was pursued by several prac- titioners, but the patients died, in spite of wine, brandy, and opium. At Cairo, Mr. Madden visited the lunatic asylum, and he favours us with some interesting observations on the state of eastern countries with regard to mental alienation. Fanaticism being a great source of insanity in most countries, and religious zeal being very strong in Turkey, one would think, a priori, that insanity should there be very frequent. The reverse, however, is the fact. There is very little madness in Turkey compared with other countries, which the author very reason- ably attempts to account for in this manner. Turkish fana- ticism is founded on certain essential doctrines of faith, which neither admit of doubt or disputation, whereas English fana- ticism wants all this consoling security : " With us, the fanatic wavers with the wind of every doctrine ; and while he works heaven and earth to gain his* neighbour to his sect, his own bosom is distracted with a thousand doubts and scruples. His anxiety for his neighbour's soul undermines liis own intellect at last ; and thus fanaticism paves the road to Bedlam." It is fortunate that insanity is rare in Turkey ; forjudging from what the author saw at the lunatic asylum at Cairo, the poor creatures are miserably provided for. The courbash, a whip made of one solid thong of hippopotamus hide, was in constant use. When he inquired about their allowance, he heard, to his horror, that there was none except what charitable people were pleased to afford from day to day. The author, very kindly, sent for some food, which the poor creatures de- voured like hungry tigers. " There was one thing I could not help remarking. The ruling passion of the Mahometan character was preserved even in insanity. One man, who begged me to give him bread, spat upon me when he got it ; another, who seized on the piece of water melon, which the women brought him, with all the eagerness of famine, ab- stained from eating it ; hungry as he was, he preferred flinging it 126 Madden 1 s Travels in Turkey, fyc. at a Christian's head rather than satisfy his craving stomach. He concealed it for near a quarter of an hour, till I was opposite his window, he then thrust his naked arm through the bars, and threw it in my face. In spite of my entreating, he got the courbash round his uncovered shoulders." While travelling in Upper Egypt, the subject of embalming naturally came under the author's notice. He was a diligent investigator of the tombs with which that district abounds ; and the following are a few among the interesting observations which his researches led to. The tombs are met with in the Libyan mountain, on the north-west side of Thebes. They perforate the mountain from top to bottom. The lowest are the most highly finished. These are inhabited by the Arabs, about three hundred of whom pass a miserable existence in these sepul- chres of pride. The staple commodity of the place (Gourna) consists in mummies, the Arabs finding it easier to live by sell- ing dead men than by the toil of husbandry. In the traffic of mummies, however, there appears to be no little portion of fraud ; for the author states it as his firm belief, that in all the cabinets of Europe, there are not probably twenty mummies in the same coffin in which they were originally deposited. Having had the good fortune to cure one of the old troglodytes of a bad fever, he gained admission, with great difficulty, to the interior of the principal tomb, and there he found the manufacture of mummies going forward : that is to say, the best mummy cases being laid open, the original was taken out and sold, and its place supplied by one of an inferior kind. A little red paint in a coffee cup set all matters to rights again. From this he proceeded through a narrow passage into another cave, which was literally crammed with mummies. They were lying in horizontal layers, as they had, in all probability, been deposited some thousand years ago. In all the sepul- chres which the author visited, he never found one mummy placed upright. Yet Herodotus so describes them. He pur- chased three mummies from his old friend, all in excellent preservation, for about sixteen shillings, the regular cost price for such articles from the Frank agents being from ten to fifteen pounds. They illustrated the three modes of embalm- ing common among the Egyptians. The first consisted simply of drying. This could not have been practised generally in any other country than Upper Egypt, where the dryness of the air is so extraordinary. In Lower Egypt the mummies go to pieces on exposure to the external air; and at Alexandria, where the atmosphere is very humid, mummies, which had resisted corruption in a dry air for perhaps forty centuries, Madden's Travels in Turkey, fyc. 127 decomposed in as many hours. A few places in other parts of the world possess, from local causes, the same antiseptic property. The author mentions, as an instance, the vaults of St. Michael's church in Duhlin. The second mode of embalming consists in the injection of some antiseptic drugs previous to drying ; and the third, which is the most perfect and sumptuous of all, is thus effected : — The viscera are removed, and the body sprinkled with aromatics and natron. After drying, it is enveloped in folds of gummed linen, and placed in coffins according to the condition of the deceased. The great principle of embalming is the exclusion of the external air, but much is undoubtedly attributable to the agency of antiseptics. The author ascertained that one of the principal ingredients in the mummy balsam was colocynth powder. The same drug is employed in Upper Egypt for destroying vermin in clothes, presses, and storerooms; and the ostrich-feathers sent to Lower Egypt are sprinkled with it. In the head of a mummy of a superior kind, he met with a balsam, in colour and transparency like a pink topaz. It burned with a beautiful clear flame, and emitted a very fragrant odour, in which the smell of cinnamon predominated. In the heart of one of the mummies he found about three drachms of pure nitre ; the heart being entire, this must have been in- jected through the blood-vessels. Mummy powder was for- merly in use all over Europe as a medicine, and, according to the author, is still employed as such by the Arabs, who mix it with butter, and esteem it a sovereign remedy for internal and external ulcers. Another topic of inquiry suggested to the author by his residence in Upper Egypt, was the question, who are the de- scendants of the aboriginal mummified Egyptians ? To decide this point, he made a collection of the skulls of the various inhabitants of Egypt, — Turks, Jews, Copts, Arabs, and Greeks, and the following are the conclusions to which he came. The old Egyptian head is of so peculiar a form, that it would be impossible to confound it with the Turkish, Grecian, or Arabic head. It is extremely narrow across the forehead, and of an oblong shape anteriorly. Among the many thousand mummy heads which he examined, he never found one with a broad expanded forehead. In phrenological language, those anterior organs which mark the seat of the reasoning powers were not weti developed. Niebuhr and most other travellers have stated the Copts to be the great body of the descendants of the Egyptians 5 but 128 Madden's Travels in Turkey, fyc. this the author will not agree to. The Coptic head is altoge- ther of a different form. A line drawn across the orbits from one external angle of the eye to the other, is in the Copt half an inch longer than the same line of the mummy head. Hero- dotus describes the old Egyptians, among whom he was ac- tually residing, as a people of black skins and short woolly hair. The Copts have neither the one nor the other. They were, in all probability, adds the author, a colony in Lower Egypt, in the time of the Egyptians, speaking their language, but not of their race. " It is among the Nubians," says Mr. Madden, " that we must search for the true descendants of the Egyptians ; a swarthy race, with wiry hair; surpassing, in the beauty of their slender forms, all the people of the East ; living on the confines of Egypt, whither probably their ancestors had been driven by the Persians, and possessing a dialect which, though mixed with Arabic, no Arab understands." The measurement of the Nubian head corresponds with that of the mummy in every particular. Having completed his survey of Egypt, the author prepared to visit Palestine. His journey across the Desert, tedious and painful as it was, afforded him the opportunity of making many interesting observations. These we must here endeavour to abridge. Leaving San in company with his Bedouin guides, he started for Suez on a camel. The soil, for the first fifteen miles, (as far as Salehie,) was covered with a saline crust like hoar frost, which impeded vegetation, but did not altogether prevent it. The true sandy desert begins at Salehie, a string of miserable villages, with a population of about 8000 souls, shaded by a long row of date trees. A party of Bedouins, encamped in the neighbouring plains, received them kindly. A kamsin wind set in the following evening, attended with its usual debilitating effects. The sun was obscured with yellow clouds ; the air was loaded with particles of sand ; breathing became difficult. Sand was driving in furiously with the wind through every cre- vice in the tent, penetrating books and clothes, though tied up in a hair skin sack ; it even got into the author's watch-case. The thermometer, at two o'clock, stood at 110° in the shade, and in the sand outside the tent, at 135°. , The tent itself was like an oven. Starting at dawn next morning, our traveller soon lost all trace of vegetation ; and he often wondered how, without landmark, trace in the sand, or compass, the Bedouins contrived to follow the proper route. Their whole study Madden's Travels in Turkey, fyc. 129 seemed to be to keep a straight course, occasionally looking back to observe their track, and to correct any little deviations. The wadys or wells where they took up their stations for the night, afforded some bad water. The dew which then fell was heavy. The Bedouin maxims for preserving health in the Desert are highly extolled by the author. They are, never to drink in the day-time, nor to sleep with the head uncovered. The more a traveller drinks during the day, the more thirsty he gets ; at night, he may drink to his heart's content. The Bedouins seem to follow the example of their camels, and lay in overnight a stock of water for the next day's journey. The author is half inclined to attach some value to the Arab notion of a morbific influence in the moon. Ophthalmia and catarrh are especially considered to be owing to moonbeams. " Strange as this may seem," says the author, " I really believe there is some influence more than that of common dampness in the nights here.'' 1 He was strangely perplexed with that singular phenomenon of the Desert, the mirage ; but this we must allow him to describe in his own animated language. " We had now journeyed in the Wilderness three days without meeting a human being', and without seeing any living creature. With all my endeavours to resist the delusion of the Mirage, I found it quite impossible this day to persuade myself that my senses did not deceive me. At one moment, the rippled surface of a lake was before my eyes ; at another time, a thick plantation appeared oh either side of me ; the waving of the branches was to be seen, and this view was only changed for that of a distant glimpse of a city: the mosques and minarets were distinct, and several times I asked my Bedouins if that were not Suez before us; but they laughed at me, and said it was all sand ; and what appeared to me a city, a forest, or a lake, the nearer I endeavoured to approach it the far- ther it seemed to recede, till at last it vanished altogether, ■ like the baseless fabric of a vision, leaving not a wreck behind.' If I were to speak of the nature of the Mirage from my own sensations, I should say, it was more a mental hallucination than a deception of (the sight ; for, although I was aware of the existence of the Mirage, I could not prevail on myself to believe that the images which were painted on my retina were only reflected, like those in a dream, from the imagination ; and yet so it was." Vol. ii. pp. 199, 200. The theory of the formation of a sandy desert occupied the author's thoughts. Whence came the accumulation of sand ? Did it always exist there, and occupy the same extent of sur face ? or can its origin be traced to depopulation and the want of cultivation ? The sight of the wide ocean of the Wilderness JULY— sept., 1829. K 130 Madden's Travels in Turkey, tyc. naturally suggested these questions, but their solution, says Mr. Madden, is far from being easy. He scouts Dessaix's notion that Nature, having expended all her art in perfecting the rest of the world, left the Desert but half made up ; and throws out the following for want of a better explanation : — " The Deserts, I imagine, from the peculiarity of their situation, were the last places from which the waters of the Deluge retired; consequently the deposition of sand, in those places, was much greater than elsewhere. This sand is identical with that of the ocean ; it is formed of the same transparent particles of quartz and silex. In all probability, in ancient times, it did not occupy the tenth part of the surface which it now does ; but when population diminished and cultivation ceased, the sands in the interior were dispersed by the prevailing winds, particularly those of the north and west, over the plains ; and the soil, for want of irrigation, be- came an arid surface: plantation, which above all impedes the ac- cumulation of sand beyond it, when no longer attended to, favoured the desolation of the land. * On the seacoast, particularly of Egypt, the flatness of the country allows a free passage to the winds, which come loaded from the shore with particles of sand. Thus I particularly remarked on the shores of Rosetta and Damietta, near the Boghas, the setting up of a small stick on the shore would be a sufficient nucleus, in the course of a few months, for the formation of a mountain of sand. One thing is certain, that wherever there is water, no matter in what part of the Wilderness, there vegetation is to be found. The stopping up of canals, and the want of irrigation, are the great causes of desolation which favour the extension of the Desert. The country from San to Salehie, and probably to Suez, was formerly a cultivated country : the ruins of palaces, such as those of Zoan and that of the Beit Pharoon, now in the middle of the Desert, prove that the country around them must have been cultivated, and that, at a very short period before our era." The latter half of the second volume is occupied with some very interesting pictures of the Holy Land. We can only find room, however, for the following sketch of the Dead Sea, or the Sea of Lot, as the natives call it. From the summit of a sterile rock, he first looked down upon the glossy lake, three hundred feet below him. The towering mountain on the opposite coast coast appeared almost ten miles distant. " The moon was shining in all her oriental splendour, on the desecrated scene; the shadows of the rugged promontories around me were reflected on the lake ; but on its surface not a ripple was to be seen ; the silence of death was there, and the malediction of heaven was written on the soil ! For miles around me there was Madden's Travels in Turkey, 8rc. 131 life in neither air, earth, nor water. I sickened of the prospect; my spirits were completely overpowered. " I reposed on the bare rock for half an hour ; my feet were cut in many places with the sharp flints which abound here, and it was with difficulty I could descend the mountain. About six in the morning I reached the shore, and much against the advice of my excellent guide, I resolved on having a bath. T was desirous of ascertaining the truth of the assertion, that * nothing sinks in the Dead Sea.' I swam a considerable distance from the shore ; and about four yards from the beach I was beyond my depth ; the water was the coldest I ever felt, and the taste of it most detestable ; it was that of a solution of nitre, mixed with an infusion of quassia. Its buoyancy I found to be far greater than that of any sea I ever swam in, not excepting the Euxine, which is extremely salt. I could lie like a log of wood on the surface, without stirring hand or foot, as long as I chose ; but with a good deal of exertion I could just dive sufficiently deep to cover all my body, but I was again thrown on the surface, in spite of my endeavours to descend lower. On coming out, the wounds in my feet pained me excessively : the poisonous quality of the waters irritated the abraded skin, and ulti- mately made an ulcer of every wound, which confined me fifteen days in Jerusalem ; and became so troublesome in Alexandria, that my medical attendant was apprehensive of gangrene." On the shores of the lake the author found several fresh- water shells, and the putrid remains of two small fish, which he believes to have been carried down by the Jordan, for he is convinced that no living creature is to be found in the Dead Sea. He spent two hours in fishing, but he only caught some bitumen. The face of the mountains and of the surrounding country bore to him all the appearance of a volcanic region, though he confesses he neither found pumice-stone nor ge- nuine black lava. The soil was covered with white porous stone and red- veined quartz. On the mountains on the western side of the lake were large quantities of the stink stone, the recent fracture of which produces a strong smell of sulphur- etted hydrogen. The surface of the water on these shores is covered with a thin pellicle of inflammable asphaltum. This proceeds from fissures in the rock on the opposite beach. After coagulating in the cold air, it cracks in pieces with an explosion, and is drifted over to the western beach. On com- ing out of the water the author found his body coated with it, and likewise with an incrustation of salt, about the thickness of a sixpence. The rugged aspect of the mountains, the ter- rible ravines on either shore, the romantic forms of the jagged rocks, all prove that the surrounding country has been the scene of some terrible convulsion of nature. I have no hesi- K2 132 Madden's Travels in Turkey, fyc." tation, adds the author, in saying, that the sea which occupies the sites of Sodom and Gomorrah, Adam, Seboim, and Segor, covers the crater of a volcano ; and that, in all probability, heaven made that mode of destruction the instrument of Divine vengeance. A bottle of the water of the Dead Sea, which Mr. Madden brought home with him, was analyzed last winter by Dr. William Gregory, at the London University. The following is his analysis : — " Chloride of sodium, with a trace of bromine 9.58 Chloride of magnesium . . . 5. 28 Chloride of calcium .... 3.05 Sulphate of lime . . . 1 5im< . 1.34 ■ it h i\Kjh J ' / firf 19.25. " The most extraordinary circumstance perhaps to be remarked is, that there is no visible outlet to the lake, notwithstanding that the Jordan is continually flowing into it. Dr. Shaw calculates that the Jordan daily sends into the Dead Sea six millions and ninety thousand tons of water, and yet there is never any visible increase or diminution in the height of the water, though Chateaubriand erroneously states that it varies at different periods. Its greatest breadth does not exceed ten miles, and its extreme length is about seventy." With this we must conclude our extracts from Mr. Mad- den's very interesting volumes. We had marked many other passages for notice, for the author was very observant, and many curious facts of a scientific nature will be found dispersed through his pages. But we have said enough, we think, to attract the reader's attention to the work, and to impress him with a favourable idea of Mr. Madden's talents. One of the great merits of the book is its adaptation to so great a variety of tastes. The physician, the divine, the politician, and the mere lover of adventure, will find in it wherewithal to interest him ; and the sketch of the work now given will, at least, suffice to show, that it is not unworthy the careful perusal of the man of science. 133 Further Recommendations resjiecting the Use of Lights in the Cornish Fisheries. Dear Sir, I attempted some time ago, and through a former number of your Journal, to call the attention of the proprietors of the Cornish fisheries to the probable advantages that might be derived from the use of lights, as practised in so many parts of the world, towards attracting the shoals of the pilchard, or inducing them to come nearer to the shore than it is conceived they have done for some years past. That this notice did not fail of its intended effect, is at the same time a proof of the influence of your Journal, and an inducement to renew the same subject in this manner, rather than through the common and vulgar method of a newspaper. But it proves what is of much more consequence, the activity of mind of that really enlightened and watchful people : since it is rare to find im- provements, even when established, instead of suggested, as in this case, adopted by any class of persons accustomed to a routine, and since no other fishermen throughout England or Scotland have thought fit to make the same experiment. Such conduct is an encouragement towards bringing this subject once more under the public notice ; and, if I am not misinformed as to the management of these trials in Cornwall, to which, if rightly represented to me, their failure may pro- bably be traced, a few further remarks on the same subject cannot be misplaced, and may possibly lead at some future time to better success. As I understand, (I hope the report was correct,) the method alone that was adopted was to make lights on shore, hoping that by this method the shoals which might possibly be swimming far off might be enticed toward the land, where alone, and in very shallow soundings, this, whicrf is a seine fishery, can be con- ducted. If no other mode was attempted, perhaps I ought to take part of the blame to myself, since the remarks made on their tendency towards the Eddystone lighthouse, a tendency which, as to all fish, will be found to hold almost universally where lighthouses exist, might have seemed to indicate that to imitate this by means of a light on] shore would have been 134 Dr. Mac Culloch on the Use of sufficient. Let me be permitted, therefore, to suggest what I consider more likely to be successful, premising also a few remarks, which are, however, unfortunately little more than hints and conjectures. I have shewn on a former occasion, in your Journal, that the changes of the herring, as to place, are even more capricious than those of the pilchard have ever been, while in some cases also their abandonment of particular shores has proved parti- cularly durable. Nor is this less true of all fishes, though most conspicuous in the gregarious ones. The cause would concern us more, could we find the remedy ; though we cannot, it is still an object of rational curiosity. And it probably consists in previous change of place, or deficiency in their natural food, though of this we can equally give no account, and have only removed the difficulty from one set of animals to another. That the occasional disappearance or diminution of gregarious fishes, perhaps in particular, is also sometimes dependant on epidemic, or epizotic disease, I have suggested to be probable in another work, but cannot enlarge on it here. Now, as to the actual fact of the variable presence or abun- dance of those endless and multitudinous marine animals which are probably the food of various fishes, there can be no doubt, although naturalists, like fishermen, have seemed to pay no attention to it ; nay, not even to the existence of such animals ; and after all their voyages and studies, have utterly overlooked, not ninety-nine in a hundred, but far more, even of those which swarm about our own shores, to say nothing of the vast ocean through all parts of the world, which they have traversed on these very pursuits. My own experience is narrow, but it is at least sufficient to establish the point. And the general result, as it bears on this question, is, that having discovered nearly two hundred undescribed species, rather by accident than de- sign, since it was not my pursuit, in the short space of six weeks, and with a very few hours of those weeks, on a very limited tract of coast ; and further found that in such places the whole sea was almost a mass of life, it cannot but follow that, con- sistently with the universal order of nature, these are the very food of the other tribes which exceed them in magnitude, and that here, probably, in particular, the great armies of the grega- Lights in the Cornish Fisheries. 135 rious fishes, such as the pilchard and herring, find their food. To suppose that they do not eat, as fishermen imagine, because food is not found in their stomachs, would be an anomaly in the laws of nature, that no sound physiologist can admit. • Nor, indeed, is that presumed fact fairly stated. If the stomachs of these fishes are widely examined they will not be found empty, though we cannot detect organized forms in them, as we find entire crabs in the stomach of a cod-fish. Nor is this surprising, when we consider how small and how tender the tribes of marine worms and insects are, and how rapid is the digestive power of fishes. And, to come more nearly to the point in question, I have had further occasion to observe, during various summers in the same seas, that while some shores abounded in such animals, such food, others were entirely destitute, and not only so, but that in one summer, during two entire months, scarcely a single animal was to be found, not one medusa, for example ; while, in a previous or subsequent one, the seas were alive with them. Here then is, or may be, a cause, or the cause, of the recent absence of the pilchard from the Cornish coasts, or of its com- parative absence, that absence concerning this fishery, imme- diately, as it relates to the shallow soundings near the shore. But whatever the cause be, if their only change is to have quitted those soundings for deeper water, as has been more than once said, it is by the project in question that it is pro- posed to recal, or entice, and circumvent them ; should they have entirely abandoned the coast or channel, or should the race be absolutely diminished, there can be no hopes. But if they do revisit the coast still, however distantly, a fact which can be ascertained, I must think that Cornwall will not show its usual acute attention to commerce or industry, if it does not persevere in these efforts, and in a more efficient manner. The contingent gain so often experienced is tempting, and it is more- over true that a very extensive capital is lying dormant, or pro- ducing actual and annual loss. They may be reminded here, that the places of the fish during the time of the trials which they made might have been such as to render the lights invisible, or so distant as to. render those inefficacious ; nor, speculating on this influence as expe- 136 On the Use of Lights in the Cornish Fisheries, rienced in other fisheries, should I consider that a light on the shore would engage their attention, unless they were already in such depths as to have permitted the use of the seine. Hence, then, I would suggest to the fishermen the adoption of the mode actually practised in the Mediterranean and the Ame- rican rivers, or elsewhere ; and this is, to carry their lights to sea, or to establish a sufficient fire-boat as the leader, and as an essential part of the arrangements for a seine. It is not necessary to say how this ought to be constructed ; it is suffi- ciently obvious, since its essence is a grate with flaming fuel, so as to maintain a large, brilliant, and durable light. Nor need I suggest to these active and keen fishermen that their object should be to attempt, first, through scouts, to discover where the fish are, and then by means of the light to entice them to follow into the requisite sounding. It is not easy to believe that it would be inefficacious, nor to admit this proposal to be termed a wild speculation, because it would be a very sin- gular anomaly that this fish alone, of all those on which the experiment has ever been tried, should be uninfluenced by that which influences the whole race, apparently because to the whole, as 1 have shewn when explaining the use of the uni- versal luminous property of fishes, it is the indication of the presence of their food, their general guide to their prime ob- ject, through the darkness of the night or the deep ocean. Thus have I taken the liberty to urge this question once more on the proprietors of these fisheries, regretting only that I cannot hope to be a witness, or to assist more usefully, and making the only necessary apology if I have here proceeded on wrong information. I have yet also, however, to learn, why the seine should be the exclusive instrument of the pilchard fishery, why the driving or herring net may not be applied to the one case as well as the other, if the fish are determined to hold to the deep water. The captures might not be so great, but the necessary capital is less ; and if the herring fishery is a profitable trade, why would not the pilchard one be the same, under the same system? when the joint value of the fish and the oil are, I believe greater, surely at least equal to that of the herring. I am, &c, J. Mac Culloch. 137 On Cookery in general, and on the Works of Ude and Jarrin in particular* We are induced to particularise the works of Messrs. Ude and Jarrin, because they form the most complete " Code of Cookery" ever presented for the world's edification ; and also because we are convinced that the well-being of the nation depends more on that useful science, scienxe as we are now bound to call it, than the public in general are aware of. It might, perhaps, be going rather too far, to charge the atrocities of the French Revolution to those " Artistes" who left their ordinary duties to turn orators, or to say that the cruelties of Robespierre and Carnot, with the other monsters who acted in the national tragedy, arose from the crudities of undressed viands ; and yet, when it is recollected that all the useful arts were done away, and cookery amongst the rest was so unnaturally misused to be applied to the purposes of state, when the country was embroiled^ — the " First Etat," in a, fer- ment, — the Noblesse in hot-water, and M. de Colonne mak- ing a hash of affairs ; we repeat, that when ministers thus usurped the jirofessor's chair, (his stew-pan we should rather say,) and by their inability the state cauldron was boiling over, it was no wonder that domestic cookery should fall into disre- pute. In fact, the c< Chef de Cuisine" was superseded by the " Chef d'Armee ;" as was the " Batterie de la Cuisine" by the " Batterie de la Guerre." This state of affairs is feelingly alluded to and explained by M. Ude. The Goddess of Reason employed no (i Maitre d'Hotel." The Parisian dealers in " JEpice Fine" were as cruelly treated as Poor Barto-Valle, and melancholy Burgess; Victims of Pitt, of Huskinson, and Sturges. Our author, Ude, begins his useful book with an elaborate history of French cookery, headed by a Greek quotation, which we at first sight took to be /xsya xaxov, and that, by a free translation, being made " great cake," it might have reference to pastry and pie-crust ; but on closer inspection we found it to be /xEya aofMc, and other Greek words, implying, " great 138 On Cookery in general. mouth, great understanding." Under which is a more intel- ligible but homely observation of the great lexicographer, Johnson, " that he who does not mind his belly will hardly mind any thing else." French cookery seems to have been in a very inferior state, up to the time of the Reformation, when the illustrious Luther made mastication, as well as morals, an object of considera- tion : ancient dogmas on dishes were done away, and freedom of eating and thinking came into fashion together; the enjoy- ments of feasting succeeded the severities of fasting ; and the great Gonthier appeared to raise the culinary edifice, as .Descartes raised that of philosophy. The English reader, whose excursions in culinary affairs have not extended beyond the pages of that primitive old lady, Mrs. Glasse, may never have heard of d'Alegre, Sou- vent, Richant, and Mezelier, but it is not to be believed that there can be any one unacquainted with the "great Gon- thier !" he who overturned bromatoloyical traditions, and esta- blished the nervous glands as the sovereign judges of the table ! —