ast ress epee sae aoe Fit, a Galea Sate Syl Se i ee ee teow Rees Ee ees = z ri eel 2. pepe c ~ es SUR ies : wee 3 Sas THE Evinburgh JOURNAL OF SCIENCE, CONDUCTED BY DAVID BREWSTER, LL.D. F.R.S. LOND. AND EDIN. F.S.S.A. M.R.I.A. CORRESPONDING MEMBER OF THE INSTITUTE OF FRANCE; CORRESPONDING MEMBER OF THE ROYAL PRUSSIAN ACADEMY OF SCIENCES ; MEMBER OF THE ROYAL SWEDISH ACADEMY OF SCIENCES; OF THE ROYAL SOCIETY OF SCIENCES OF DENMARK; OF THE ROYAL SOCIETY OF GOTTINGEN, &c. &c. VOL. IV. NEW SERIES. OCTOBER—APRIL. THOMAS CLARK, EDINBURGH: T. CADELL, LONDON. AND MILLIKIN & SON, DUBLIN. M.DCCC.XXXI. . CONTENTS OF THE EDINBURGH JOURNAL OF SCIENCE. No. VI. NEW SERIES. Page Art. I. Biographical Notice of the late M. I.e Baron Fourier, Perpetual Se- cretary of the Academy of Sciences, and Member of the French Aca- demy. By M. Vre1Lu Botssosiin. : II. On various Improvements in the casting, Weaibiaig: &e. of Specula for Reflecting Telescopes, with sundry Hints to Amateur Opticians. By R. PotTErR, Esq. Junior. Communicated by the Author. III. Account of the Habits and Structure of a Male and Female Orang- Outang, that belonged to GEorGE SwinTON, Esq. Secretary to the Government, Calcutta. By J. Grant, Esq. ee Surgeon, Calcutta. In a Letter to Dr BREwsTER, IV. An account of a Peculiarity not hitherto dhistsined | in the Ankle, or Hock-joint of the Horse ; with Remarks on the Structure of the Ver- tebre in the Species of Whale, entitled Delphinus Diodon. By Ro- BERT J. Graves, M. D., M. R. I. A., King’s Professor of the In- stitutes of Medicine, Honorary Member of the Royal Medical So- ciety of Berlin, of the Medical Association of Hamburgh, &c. &c. VY. An Account of Experiments to determine the reflective powers of Crown, Plate, and Flint-Glass, at different angles of incidence ; and an investigation towards determining the Law by which the reflective power varies in transparent bodies possessing the property of single refraction. By R. epee Esq. Junior. Communicated by the Author, » VI. Mineralogical, Geological, eid Chemical Notices, Communicated by Dr CHarLEs HaRTMANN, of epithe! on the Harz, M. W. S. &c. VII. Experiments on Ocular Ristien eh by the sake of the Sun’s Light on the Retina. By Sir Isaac NEwTon, VIII. On the Mean Temperature of TwenTy-NINE different paces in the State of New York for 1829, a 13 27 47 53 68 75 77 li : CONTENTS. IX. On thé Direction of the Diluvial Wave in the Shetland Islands. By S. Hipsert, M. D., F. R.S. £., &c. Communicated by the Author, r ° ss : J X. Memoir on Barometric Instruments acting by Conspeuitiild consider- . ed particularly in their application to the Measurement of Heights ; including some new Trigonometrical Determinations. By James D. ForseEs, Esq. Communicated by the Anthor, : o- XI. On a new variety of Mineral Resin. By James F. W. JOHNSTON, M.A. &c, &c. Communicated by the Author, - XII. On Improved Methods of computing the Angles of Spherical Triangles when the sides are given, By Jamus Taomson, LL. D. Professor of Mathematics in Belfast College, : ° ° XIII. Some general Remarks on Bodies having a like Composition, but un- like Properties. By Professer BERZELI1Us of Stockholm, XIV. On the Phenomena and Laws of Elliptic Polarization, as exhibited in the Action of Metals updm Light. we Davip pie LL. D. F,. R. S. Lond. and Edin. XV. Account of a remarkable Waterspout sneotnpnalil with a ( Ieuiae ' Meteor. By M. Grosirtwy, a te XVI. ANALYSIS OF SCIENTIFIC BOOKS AND MEMOIRS, Principles of Geology, “being an attempt to explain the former changes of the Earth’s Surface by reference to causes now in opera- tion. By Cuartes LYELx, Esq, F.R.S. Foreign Secretary to the Geological Society. In Twe- Volumes. Vol. I. London, 1830. Pp. kveand Shy. hk te as XVI. SCIENTIFIC INTELLIGENCE, 7 te ok NARUBAL PHILOSOPHY. METEOROLGY.—}. Account of the Georgia Meteor and rolite. 2. Notice of the circumstances attending the fall of the Tennessee Meteorites, May 9, 1827, ; : : j . ; 181, ¥E. CHEMISTRY. 3. Composition ef Mellitic acid. 4 Succinie Acid. 5. Paratartaric Acid. 6. Salicine. 7.. Carburet of Sulphur not decomposed by Electric forces, 183, Il, GENERAL SCIENCE, 8. Mortality among Leeches during storms. 9. Prizes, . 184, XVIIF. List of Patents granted in Seotland since September 16, 1830, XIX. Summary of Meteorological Observations made at Kendal in Sep. tember, October, and November 1830. By Mr SamuEn MarsmaLu. Communicated by the Author, ‘ . 7 XX. Register of the Barometer, ‘Fhermometer, and Hain Gages kept at Canaan Cottage. By ALEX. ADEE, Bsq. F. R.S. Edinburgh, ~~ Page 85 91 122 424 130 136 165 170. ib. 181 182 184 185 185 188 ERRATA, Vol. III. Page 153, line 6, for errors read terms. Id. _—_note, line 4, for @ read c. Page 204, line 17, for cightieth read sixtieth. Page 290, line 16, for J made read made. Page 293, line 2 from the bottom, for pogssiwm read potassium. - Poe | a4 et » *,* Communications, Books, and Memoirs for this Journal to be addressed to Dr BrewstER,-to be forwarded through Mr T. Capvett, Strand, London, or Mr Tuomas Ciarx, 38, George Street, Edinburgh. Our Foreign Correspondents are requested to transmit Com- munications, &c. through MM. Bossance and Company, 60, Rue de Richelieu, Paris, or 14, Great Marlborough Street, London. b») int. i er ARS ‘ * Q inetd dimairett 02 heeange oe aurca sie otf AM . CONTENTS OF THE EDINBURGH JOURNAL OF SCIENCE. No. VIII. NEW SERIES. Page Ant. I. Meeting of the Cultivators of Natural Science and Medicine at Ham- burgh, in September 1830. By James F. W. JonNSTON, M. A. &e, &c. Communicated by the Author, 189 II. Project for facilitating the Manufacture of thseneete Object-Glasses for Engyscopes. By C. R. Gortne, M. D. &c, Communicated by the Author, 244 III. On the Phenomena wai in of Elliptic Polatizaiton, as exhibited in the Action of Metals upon Light. By Davip BrewsTER, LL. D. F. R. S. Lond. and Edin. Concluded from last Number, p. 165, 247 IV. Account of other Four Cases of Spectral Illusion. (Continued fiom No. vi. p. 245.) 261 V. On the Electro-magnetic vainpation of para Veins in the Mines of Cornwall. By RosertT WERE Fox, Esq. of Falmouth, Hon. Mem. Plymouth Institution, and M. R. Geological Society of Corn- wall. Communicated by the President, . 263 . Observations on the Action of the Voltaic Pile. By M. Saa'woecieraisy _ Ina Letter to M. Arago, ’ 273 VII. On the Spontaneous Inflammation of powdered Chaceoal' in amet masses. By M. AvBERT, Colonel of Artillery, 274 VIII. History of the Brown Coat Formation of the nee Wheiaionds By S. Hippert,; M. D., F. R. S. E., &c. Communicated by the Author, : : 276 IX. Observations on the Mean Ni iaeiatae of the Globe. By Davrp BREwsTER, LL. D. F. R.S. Lond. & Edin. 300 X. Experiments relating to the Reflective Powers of Crown, Plate, and Flint Glass, with theoretical considerations.—(Continued from last Number, p. 67.) By R. Porrer, Esq. Junior, Associate of the Society of Arts for Scotland. Communicated by the Author, ~ 320 XI. Memoir on Barometric Instruments acting by Compression, consi- dered particularly in their application to the Measurement of Heights ; including some new Trigonometrical Determinations. By James D. ForsBEs, Esq. F. R. S. Ed. Communicated by the Author, 329 iv CONTENTS. ‘ Page XII. Observations on the Temperature of Springs made daring a voyage to Mount Elbrouz in Caucasus. By M. Kuprrer, Member of the Acadeniy of Sciences of St Petersburg, ° 351 XIII. Observations on the recent adjudication of the Wollaston Medal to Mr Wiiiram Smita for his Geological discoveries, _ 357 XIV. On the nature of the Rings formed by the double refraction of Quartz. By G. B. Airy, Esq. Plumian Professor of Experimental Philoso- phy, Cambridge, aR pf ‘ . ° 362 XV. ANALYSIS OF SCIENTIFIC BOOKS AND MEMOIRS, 364 I. A Rationale of the Laws of Central Vision, comprising the Laws of Single and Erect Vision, deduced upon the Principles of Dioptrics! By Joun Fearn, Esq. t ib. I]. An Experimental Inquiry into the Number and Propet of the Primary Colours, and the source of Colour in the Prism. By WatTER Crum, Esq. . . . 367 III. Sections and Views illustrative of Geological Penetislias: By © Henry T. DE ta BECHE, F.R.S., F.G.S. . ‘ 368 XVI. SCIENTIFIC INTELLIGENCE, — , . 369 I, NATURAL PHILOSOPHY. ELEcTRICITY.—1. On the Laws of Electrical Accumulation. By Mr Snow » Harnis, Plymouth, a . e « « ib. Ih CHEMISTRY. 2. Existence of Copper in Vegetables and Blood. 3. On the Inflammation of Phosphorus in-a partial Vacuum. By D. A. BacueE, M.D. Profsof Nat. Phil. and Chem. Col. Depart. Univ. Pennsylvania, . 369, 370 4 III. NATURAL HISTORY. Mineratocy.—4. On Xanthite and its crystalline form. By Lt. W. W. MaTHueEnr, Assistant Prof. of Chem. and Min. U. 8S. M. A. - B71, 372 ZooLoey.—5. Notice regarding the Salamandra atra. By MrSrarx. 6. Vision of the Mole, by GEOFFROY St-HILAIRE, F 373, 374 Iv. GENERAL SCIENCE. 7. Great, Scientific Meeting to be held at York. 8. Observations on the influence of Cold.on New-born Children. 9. Ossification of the Vitreous Humour. 10. Zoological Weather Glass. : : ¥ _ 374, 375 XVII. Register of the Barometer, Thermometer, and Rain-Gage, kept at Canaan Cottage. By ALEX. ADIE, Esq. F. R.S. Edinburgh, 376 , 870 $6 S500 40 $300 oe Edin” Journal of Science N. Series Vol IV. B Fig. 5 s c e g mM c D b ad ft a 7 . ; Fig .6 , Fig 7 : B a4 x A x c i“ g zr oO 1 r a Lazars. scudp! THE EDINBURGH JOURNAL OF SCIENCE. Art. I.—Biographical Notice of the late M. Le Baron Fou- rier, Perpetual Secretary of the Academy of Sciences, and Member of the French Academy. By M. Vrei.n Bots- JOSLIN.* Science has lost, in the person of M. Fourier, a geometer and a natural philosopher of the first order, Literature, a writer of superior talent, and France, one of the men who have done her most service in high situations, and who have honoured her most by their labours and their discoveries. It is not his eloge that we propose here to give; this task, or rather this honour, can belong only to such of his colleagues as have followed him in his career ; they also are able to ap- preciate his genius. We are desirous only, in this notice, to give details purely biographical ; and those which we are about to present, having been collected in conversation with the il- lustrious author, in that of his friends, in the perusal of his works, and of the printed and manuscript writings which have been intrusted to us, will still receive a powerful interest from the subject to which they relate, and from their great accu- racy. * This interesting notice, which we have translated from the Revue En- cyclopedique for June 1830, p. 552, is, with the exception of some changes | _ and additions, the same as that which has been furnished by the author to the Biographie Universelle et Portative de Contemporaines, a work of which he is the editor. NEW SERIES, VOL. Iv. NO. I. JAN. 1831. A 2 M. Boisjoslin’s Biographical. Notice of Jean-Baptiste-J oseph Fourier, born at Auxerre, on the 21st March 1768, was descended of a family originally from Lor- raine. His grand uncle, Pierre Fourier, reformer and general of the order of Regular Canons, did honour to the clergy by his great virtues, and instituted a congregation of women, ad- ding to their three vows a fourth, which was not the least re- spectable, and certainly the most useful, that of instructing gratuitously the children of the poor. Several houses of this order have been preserved in France, and alas in the capital. M. Fourier was placed, when very young, at the Military ‘School of Auxerre. He exhibited early a great degree of intel- ligence, and went through his classes with such rapidity, that he completed his course at the age of thirteen. It was then that he began to devote himself with ardour to the study of mathematics. ‘This study, however, did not prevent him from pursuing literature, and he seemed to anticipate that litera- ture, as well'as science, might prove to him a source of dis- tinction. Before he had reached his eighteenth year, he made several important mathematical discoveries, which are con- tained in a memoir, in which competent judges recognized the precocious genius of Pascal. About this time he was appointed professor of mathematies in the: Military School at which he had been educated. A few years afterwards, when the Normal School was instituted at Paris, M. Fourier was sent to it! by his department as one of the professors: the most capable of cultivating the philosophical part of the sciences... It was soon found to be necessary to divide the auditory into several sections, for the purpose of scientific conversation among the pupils, and M. Fourier was chosen one of the directors of these conferences. More recently the Central School of Publie Works, afterwards called the Polytechnic School, was organized on a permanent basis ; Lagrange and Monge nominated Fourier one of the professors of this institution, for which Europe has so much envied France, and in which the sciences were then taught by those very persons who had extended their boundaries. The easy and graceful elocution of the young professor, the urbanity of his manners, the interest which he shed over science by the profound ideas with which he enriched his lec- 4 the late M. Le Baron Fourier. 3 tures, and the philosophical manner in which he presented © them, made him generally beloved and respected by his pupils. It was about this time that the useful and glorious conquest of Egypt had been planned in silence. The great man who directed this memorable expedition was anxious that war should become the means of civilizing conquered nations, and the Commission of Egypt was organized. The varied know- ledge and talents of M. Fourier made him appreciated by the government. He was placed in the list of Savans who were to accompany General Bonaparte, and he was directed at the same time to prepare the pupils of the Polytechnic School who were to be joined to them. M. Le Comte de Chabrol, now pre- fect of the department of the Seine, was one of the pupils then named. This circumstance could not but have some influence over the career of this learned administrator, and, if this were the case, it would be a title which M. Fourier had long ago ac- quired to the gratitude of the city of Paris. The literary life of M. Fourier is intimately connected with this distant expe- dition, the object of which was then unknown, and which has become a celebrated epoch for the arts and sciences, as well as a brilliant episode of glory for our arms. After the submis- sion of Cairo, the Institute of Egypt was created. M. Fourier was comprised init. , Experience had shown the necessity of establishing in learned societies perpetual secretaries. The In- stitute proceeded to this nomination, and M. Fourier was unanimously elected. On several occasions he presented im- portant memoirs to this Institute; but political cares were soon mingled with the labours of the philosopher ; M. Fourier was chosen Commissary of the French Army to the divan formed of the principal Ulemas of the town of Cairo and the provinces, after the prudent severity of the General-in-Chief had calmed the turbulence of the insurgents in the capital. Bonaparte had neglected no means for keeping up useful and familiar relations with the inhabitants, and the art of commu- nicating with men, which M. Fourier possessed in a high de- gree, rendered him highly qualified for establishing a union between the civil administration and the army. The General- in-Chief at this time set out to counteract the great plot which was then organizing against him in Syria. M. Fourier was 4 M. Boisjoslin’s Biographical Notice of retained at Cairo. During the absence of the supreme chief the power of the administration increased, and, as M. Ville- main remarked, the perpetual secretary of an academy found himself almost the governor of one-half of Egypt. Sometime afterwards, the administration of justice was also confided to M. Fourier, and the miseries of war were then assuaged by the benefit of laws. In quitting the army to return to France, Bonaparte had, with much foresight, left all the necessary orders for facilitat- ing the noble excursions ‘which the zeal of the French philoso- phers was about to resume in Upper Egypt.' He had divided these ardent explorers into two sections, and had seen the’ne- cessity of appointing a chief for each of them: M. Fourier was elected one of these chiefs. Hitherto the French Savans had been but seldom able to advance into the southern pro- vinces of Egypt. Victory having now opened this country to them, they visited more freely the magnificent ruins of Thebes, and each of them took a part in those discoveries which we may call conquests over the enemy ; since, according to the ex- pression of M. Fourier himself, they were made in perilous journeys, where the geometer, the artist, the pupil of Buffon, calculated magnitudes, designed monuments, and observed na- ture under favour of a victory, or during the interval of two engagements. Theyascended the course of the Nile, and visited the mysterious island of Elephanta. It was in this celebrated voyage that M. Fourier collected on the spot those lively im- pressions, of which he afterwards gave so animated an ac- count. If his zeal was surpassed, it was only by that of the indefatigable Denon, but in general, no person gave more ef- fectual assistance than he did to the compilation of the great work on Egypt. He conducted with no less boldness the high functions, the important duties which he had to discharge in the army. When Morad, dreading the departure of the French, offered to treat with Kleber, through the medium of his wife, the beautiful Scitty Nefigah, whom this Bey had carried off from Aly, it was M. Fourier who concluded the treaty with that celebrated woman ; an alliance which brought about that peace which was so much desired, but which lasted for too short a thelate M. Le Baron Fourier. 5 time. It was he also who expressed the sorrow of the heroic army of Egypt, when the sword of a fanatical assassin pierced the unfortunate Kleber. From the summit. of a bastion M. Fourier, celebrated, in the presence of the whole army, the conqueror of Maestricht and Heliopolis. Upon uttering these words, “ I take you to witness, ye intrepid cavalry, who ran to save him on the heights of Coraim,” the army was affected, and the orator, partaking in the common grief, stopped,—in- terrupted by the noise of arms, and the Jamentations of so many soldiers in tears. A few months after this sad solemnity the fate of General Dessaix, who had recently left Egypt, was known at Cairo. The orator of the army of the East had to celebrate the memory of this great captain, in the very place where he had honoured the remains of Kleber, and on this oc- casion too his eloquence rose to the height of his subject. Detained in Egypt to the very end of the expedition, M. Fourier at last returned to France, with the smal! number of philosophers and warriors who had escaped from this hazar- dous expedition. After a. conquest so daring, and after so many combats of glory, there remained the labours of science, —the map of the country, and the copy of its monuments. It was at least desirable that none of the valuable marks of our expedition to Egypt should be lost. But there was reason to dread that each individual savant would wish to make a se- parate use of what he had himself collected, and that the whole mass of the results would thus be disjointed. M. Fourier, when summoned before the First Consul on the subject of the portfolios brought from the East, availed himself of this cir- cumstance to direct his attention to the subject. It was then agreed that all their riches should be collected, and that the _ work on Egypt should be published at the expence of the go- vernment. ‘The Savans, to whom this. charge was entrusted, unanimously selected M. Fourier to delineate the frontispiece of the temple, which they were about to rear to the glory of science and of the country. The First Consul was desirous of rewarding an ae who, without soliciting any distinction, had rendered him such eminent services. He wrote to Berthollet on the 18th Pluvi- oise 1801, to learn if the prefecture of the department of Isere 6 M. Boisjoslin’s Biographical Notice of would be agreeable to M. Fourier. He was appointed Pre- fect of Grenoble on the 2d January 1802. He was included in the legion of honour as soon as it was created, and he re- ceived the title of Baron, with a pension, in 1808. His ad- ministration, during the first fourteen years of it, does not seem to have suffered from his devotion to science ; on the contrary, it was benefited by it. Great public works were completed ; the draining of the marshes of Burgundy, which infected more than forty communes, was executed, and this vast and salu- tary enterprise, so often and so uselessly attempted, was ter- minated by the influence of an active administration full of wisdom and of firmness. In the midst of such important functions M. Fourier at last completed the difficult task which had been entrusted to him. During the first eight years of his residence at Grenoble he wrote the discourse which forms the historical preface to the great work on Egypt, an eloquent and well arranged exposi- tion, written, to use an expression of M. De Fontanes, with the graces of Athens, and the wisdom of Egypt, and in which he has recorded with a bold pencil the events of history, the ob- servations of science, and political views. It is in this dis- course, which is reckoned one of the finest monuments of the French language, that the author, invoking at the same time the authority of ages, and the speculations of genius, has thrown a bright light upon the enterprises which Europe may under- take for civilizing the Fast, and that we meet with some of those elevated views to which an illustrious author has more recently imparted new energies. The Institute of France having proposed in 1806 the im- portant and difficult problem of determining the laws of the propagation of heat in solid bodies, M. Fourier discovered new methods of resolving it; he verified them by very curious ex- periments made with the most accurate instruments; and in 1807 he gave a complete solution of this difficult question. His me- moir obtained the prize, and placed its author in the very first rank of philosophers. M. Fourier sent to the institute a se- cond memoir on the same subject, and these two papers form the substance of the great work which he pees 4 pub- lished. the late M. Le Baron Fourier. | In 1815, when the Emperor Napoleon landed in France, and advanced towards Grenoble, M. Fourier, by the advice of the prefect of the Var, published, on the 5th March, a ceptege for preserving order, and causing the government thé king and of the constitutional charter to be respected. On the arrival of the conqueror he quitted the city, but Na- poleon caused him to be brought back to Grenoble. In this difficult position M. Fourier was exposed to imminent danger ; but he was saved from it by the affection of the inhabitants and by the tact of the emperor, to whom he was presented in the midst of an immense concourse of people, and who ap- pointed him, on the 12th March, to the prefecture of the de- partment of the Rhone. ‘The principal inhabitants of Lyons, who knew all the advantages which might be expected from so able a magistrate in such critical times, anxiously desired that this office should be conferred upon him. M. Fourier found it impossible to decline it, but the principles of justice and moderation which always guided his conduct did not per- mit him to continue in this situation. He refused in writing to carry through the measures which the minister required of him, and he was recalled by a decree of the 12th May. Na- afterwards assured him that he understood his conduct and approved of it. Thus left to himself, our celebrated geometer came to reside in Paris. In 1816, he read to the Academy of Sciences a memoir on the vibrations of elastic surfaces, which contained several new integrations of equations belonging to dynamics. In the same year, the Academy admitted bim a member ; but Louis XVIIL., misled respecting his political conduct, refused to ratify his election by the royal sanction. In 1817, however, when he was a second time elected, the king, after an attentive examination of al] the facts, approved of the election. A short time afterwards, M. Fourier was chosen perpetual secretary of the Academy for the Mathematical and Physical Sciences. The Royal Society of London and other academies hastened to do themselves the honour of admitting him into their body In 1820, he added to his discoveries the solution ofa very complicated question : It consisted in forming differential equa- tions which express the distribution of heat in fluids in mo- 8 M. Boisjoslin’s Biographical Notice of tion when all the molecules are displaced by any forces whatever, combined with changes of temperature. These equations belong to general hydrodynamics, and we are indebted to the author for having completed this branch of analytical mechanics. It was in 1822 that this great geometer gave to the learned world his admirable treatise entitled Theorie Analytique de la Chaleur. The preliminary discourse, and particularly a pas- sage in this discourse which has specially struck us, and which has perhaps not been sufficiently noticed, would alone be suffi- cient to place M. Fourier in the number of those philosophi- cal geometers who are destined to wrest from nature some of her more hidden secrets. Before his time the effects of this universal element were unconnected with mechanical theories. The fixed laws which regulate its distribution are still un- known; valuable observations had been collected, but only partial results were known, and not the mathematical demon- stration of laws which embrace them all. The illustrious av- thor succeeded in discovering them, and exhibiting them in analytical formule, so that this theory will henceforth form one of the most important branches of general physics. His principles are deduced, like those of rational mechanics, from a few primordial facts, which ‘geometers do not consider the cause, but which they admit are the results of general observa- tion. ; The principal results of this theory. are the differential equations of the motion of heat in solid or fluid bodies, and the general equation which relates to the surface. These equa- tions, like those which express the vibrationsjof sonorous bo- dies, or the last oscillations of fluids, belong topne of the newest branches of mathematics, and one which it i of much impor- tance to improve. After having established these differential equations, it was necessary to integrate them, which consists in passing from a common expression to a proper solution sub. ject to all the given conditions. This difficult research required a special analysis, which M. Fourier has created, and which is founded on new theorems, the nature of which we cannot here explain. It may be sufficient to say, that the method de- rived from it leaves nothing vague and indeterminate in the solutions, and that it conducts them to the last numerical ap- the late M. Le Baron Fourier. 9 plications, a necessary condition of every investigation, and with- out which we should only arrive at useless transformations: It deserves to be remarked, that these theorems are applicable to questions of general analysis and of dynamics, the solution of which has long been a desideratum. We may easily judge how important this new theory ought to be in the physical sciences, and in civil economy, and how great may be its influ- ence on the progress of the arts which require the employment of the distribution of heat. The theory of heat has also a necessary connection with the system of the world. A very important class of phenomena are produced in this system by the laws which regulate its dis- tribution. It would be impossible to notice here all the unexpect- ed results at which M. Fourier has arrived. We shall mention only some of the questions which he has been able to solve. Why does the temperature of the earth cease to be variable at so small a depth in relation of the radius of the globe? What time ought to elapse in order that the climates may acquire the different temperatures that they have at present, and what causes may still change the mean heat? ‘'l’o what cause ought we to ascribe it that the globe has not entirely lost its own heat, and what are the exact laws of its expendi- ture? Independently of the two sources of heat in our globe, the one fundamental and primitive, and the other due to the presence of the sun, is there not a more universal cause which determines the temperature of the heavens in that part of space which the solar system now occupies? In this ques- tion, which is entirely new, what are the consequences of an exact theory ? How can we determine this constant value of the temperature of space, and deduce from it that which be- longs to each planet? If we add to these leading questions those which depend on the properties of radiant heat, and se- veral others, not less important, we may form an idea of the admirable investigation of this eminent philosopher. ‘The solution of these problems, which required the genius of a Newton, a La Grange, and a La Place, has shown that the temperature of the planetary spaces in our system is 58° below zero of Fahrenheit, the same nearly as that at the earth’s _ poles, which our author’s theory has also determined. We 10 M. Boisjoslin’s Biographical Notice of may now understand why the temperature of our globe is constant within certain limits, and how it happens that cold and heat do not become dangerously intense during the al- ternation of day and night, and during the variation in the earth’s distance from the sun. We learn also that the incan- descent mass which forms the interior of the globe ought to be about twenty leagues below its surface, and that the. heat which emanates from it can no longer exercise any influence on the earth’s temperature. ‘Thus has disappeared that theory of the cooling of the surface of our globe to which the pre- sence of a central fire gave an appearance of truth. The cal- culus has rectified all such errors, and those enormous planets which are situated at the confines of our system are found only to have a temperature of —58° of Fahrenheit. Having computed the law of the cooling of our globe, ori- ginally in a state of imcandescence, and having shown that ages were necessary to bring it to its present state, our readers will readily see how such questions bear upon many points of cosmology. Of late years M. Fourier was occupied with very interest- ing experiments on the transmission of heat across different bodies, and the results which he obtained were conformable to his anticipations. Among other results, he found that the heat which traverses several plates of different substances su- perposed, varies according to the order of superposition, ex- ternal circumstances remaining the same. Thus, in placing a sheet of copper between the skin and a piece of cloth, the transmission of the heat is facilitated; when the copper is placed between two pieces of cloth, the transmission is not changed ; and when placed between cloth and marble, it is di- minished. For these experiments M. Fourier contrived his T'hermo- meter of Contact, * with which he has made a great number of interesting experiments. M. Fourier has likewise made several important improve- ments in the calculation of probabilities, some of which are contained in his work On the Mean Results and on the Errors of Measures. In an excellent work on the general resolution * See the Edinburgh Encyclopedia,—Art. THERMOMETER. the late M. Le Baron Fourier. il of equations, this subject has been treated in a manner en- tirely new, and there will be found among his manuscripts, reflections as curious as they are philosophical, on the difficult points of elementary algebra, and on the theory of parallel Tt is not easy to understand how, in the midst of such cng studies, he found it possible to devote himself to the labours of literature as well as of science. M. Fourier often gave proofs of the possibility of this double effort, and it was always executed with an admirable pliability of talent. The fine eloges which he pronounced as the organ of the Academy of Sciences have placed him beside Fontenelle, Condorcet, and Vicq-d’Azyr. As ingenious as the first, but with more sim- plicity, he raises himself like Condorcet by the generality of his ideas and the universality of his knowledge, and he ap- proaches the last by the harmony, the elegance, and the ani- mated movements of his style. In 1827, the French Academy wished to pay the debt of literature to this illustrious philosopher, and on the 17th April he was unanimously admitted into the Academy of Sciences. In the same year, after the death of La Place, M. Fourier succeeded him in the council for the improvement of the Polytechnic School, and in 1828, after the fall of Villele, he was named a member of the commission appointed to re- port to the government on the distribution of the prizes grant- ed to science, literature, and the fine arts; and afterwards president of the commission of statistics established by the Minister for the Marine and the Colonies. He had refused the place of Directeur General de la Libraire, offered him by the new minister, in which he would have done much good, and it was on this account he regretted that his occupations and his health had not permitted him to accept of it. It was in the middle of such labours and studies, and of duties fulfilled with rigorous exactness, that M. Fourier found time to give proofs of the most cordial ‘friendship for his colleagues, and to receive and encourage every person who was recommended to him. Nothing could equal the charm of his conversation, at once gay, spiritual, and full of grace. These estimable qualities, and the goodness which he showed Se Biographical Notice of M. Le Baron Fourier. in his social relations, attracted to him as many friends as there were admirers of his genius. He was for several years attacked with a nervous angina. This infirmity, recently aggravated by a fall, put an end to his life rather suddenly, on the 16th of last May, 1830, in the sixty-third year of his age. Philosophers will hasten to eha- racterize what he has done for the progress of the sciences, which owe to him profound calculations and discoveries, that will render his name immortal. His obsequies were celebrated on the 18th May, in the church of Saint Jacques-du-haut-Pas, This mournful solemnity was attended by numerous deputa- tions from the Institute and the Polytechnic School, by the members of his family in profound sorrow, by his friends and acquaintances, by a great number of academicians, by philoso- phers and men of letters, whom respect or sorrow had assem- bled round the grave of an illustrious academician, an excel- lent parent, and a sincere friend of the public liberties of his country. The pall was held by M. Geoffroy de Saint Hilaire and Bontemps Beaupre of the Academy of Sciences, M. Felitz, director of the French Academy, and Syly estre de Sacy, of the Academy of Inscriptions. The procession walked to the cemetery of the East. Several discourses were pronounced over the tomb by M. Sylvestre, M, Cuvier, and by MM. Felitz, _ Girard and Jomard. The following is a list of the principal writings of M, Fourier :— 1. Mémoires sur la Statique, ‘containing the demonstration of the principle of virtual velocities, and the theory of Mo- menta, printed in tom.ii.of the Journal del Ecole Polytechnique, 1798. 2. Mémoire sur la Resolution Generale des Equations Aige- briques, presented to the Institute of Egypt. 3. Discours Préliminaire, servant de Preface Historique a la Description de V Egypte. Paris, 1810. 1 vol. folio. _. ; 4. Rapport sur les établissemens appelés Tontines. Paris, 1821. Ato. 5. Theorie Analytique de la Chaleur. Paris,1822. 4to.. 6. Several Reports on the Progress of the Mathematical Sciences. Paris, 1822 to 1829. 4 Mr Potter on Improvements in Specula, &c. 13 1. Bloge Historique de Sir W. Herschel. Paris, 1824. Ato. 8. Eloge de Delambre. Paris, 1823. 4to. 9. Two memoirs entitled Theorie du mouvement de la Cha- leur dans les Corps solides, printed in the Memoirs of the In- stitute, tom. iv. and v. 1824 and 1826. 10. Notice Historique sur la vie et les Ouvrages de Breguet. * 1826. 4to. 11. Mémoire sur les Temperatures du Globe Terrestre et des espaces planetaires. Paris, 1827. Ato. 12. Mémoires sur la distinction des Racines Imaginaires, et sur Application des Theorems @Analyse Algebrique aux ‘Equations transcendentes qui dependent de la Theorie de la Chaleur, printed in the Memoirs of the Institute, tom. vii. 1827. 13. Eloge Historique de M. Charles. 14. Eloge Historique de M. de La Place. Paris, 1829.+ 15. Mémoire sur la Theorie Analytique de la Chaleur, ‘printed in the Memoirs of the Institute, tom. viii. 1829. 16. Analyse des Equations Determinées. The author had printed the first six sheets of this important work, which he did not live to finish. ‘* The work,” says M. Navier, “ con- tains a preface, an introduction containing the principal points of algebraic analysis, which serve as the basis of the work ;— ‘a synoptical exposition, containing a detailed explanation of the subjects which ought to be treated in the work, and from which we learn that it was to be divided into seven books. The manuscript of the exposition, and of the two first books, was found complete, and to all appearance ready for press. This is the part that ought to be published first and separately. There is every reason to believe that the materials of the last ‘books exist among the author’s papers, and that these new ‘researches will not be lost.” Axt. IL—On various Improvements in the casting, working, &c. of Specula for Reflecting Telescopes, with sundry Hints to Amateur Opticians. By R. Porter, Esq. Junior. Com- municated by the Author. ‘Tuis essay on the grinding, polishing, &c. of certain metals _.* See this Journal, No. xiv. p, 201. + See this Journal, No. ii, New Series, p. 193. 14 Mr Potter on Improvements in casting and working for the specula of reflecting telescopes, being intended only for the information of amateurs, if it should fall under the peru- sal of one engaged in the pursuit as a trade, before he has the opportunity to say there is nothing in it worth knowing which was not already known by the working opticians, I say, I do not pretend to teach those who have been initiated into the mysteries of the craft by aregular apprenticeship. The great excellence of their workmanship, and the inability of any ama- teur to instruct them, is duly proclaimed by the superiority of their reflectors over the achromatics produced by their brother artists at the present day. My intention is only to add my mite to what has already been given in print by Sir Isaac Newton, Smith, Mudge, Edwards, Herschel, Lord Oxman- toun, &c.—Amateurs all,—and, though not finding a place in this list for any name from those, who, having practised the art as a means of livelihood, must have had a tenfold oppor- tunity and experience, I am not, nevertheless, inclined to blame the fraternity, Short and Company, but rather charitably to believe that they have had nothing more to communicate than what amateurs had before taught them, besides the dex- terity acquired by experience, which could not be transferred by ink and paper. In addressing myself, therefore, to amateur speculum and glass-grinders, I exhort them not to let want of success, ade- quate to their wishes, check their perseverance. ‘The art is one in which ‘they must not expect to attain perfection in their first attempt. I have heard of many who have commenced, but of very few who have produced, even tolerable specula from want of sufficient practice. With myself, it has required the experience of nearly a dozen years in the largest part of my leisure hours from busi- ness, but in which I include about two years spent in the study of chemistry, which I undertook when I found I could not get so fine a polish on metal as I wished, with the putty (cream coloured oxide of tin) and coleothar of vitriol, (red oxide of iron,) which TI purchased in the shops, and could not succeed in producing a good polishing powder of my own making, ac- cording to the directions given by Edwards. But after this course of study, during the greatest part of which I had the good fortune to be pupil to the chemist who has. done more Specula for Reflecting Telescopes.’ 15 for the science than any other man without exception, when my attention was again drawn to my old hobby, I undertook tage ie of the polishing powder with very different For many years I had continually, asked myself—what is polishing? Is it only grinding, as some have supposed, carried to as fine a pitch as we can? The answer which often sug- gested itself was, if it is only fine grinding, the polish so pro- — duced artificially must at best. be only an approximation, and infinitely inferior to the natural polish which of itself forms on the surfaces of glass, liquids, &c. From what I read on the polishing of precious stones, and from what I had seen, name- ly, that what would polish glass would grind metal, I at last concluded that polishing is a totally different process from grinding ; that in the latter the material must be harder than the substance to be ground; and that all approximation to- wards polishing by it must at last be mere approximation ; and that to produce a good polish, the polishing material must be of a nature not harder than the substance to be polished. Hence, in grinding, we proceed comparatively rapidly with a quantity of the emery, &c. running loose between the tool and the body we grind; but in polishing, the powder being softer. we never make any good progress until there is a close contact and strong adhesion between the surface of the polisher and the lens or other body in work. ‘Thus, though the powder is too soft to penetrate and tear away the substance of the glass, &c. yet when this adhesion takes place, successive layers of the surface, if I may use the expression, slide away, and it is left the smoothest possible: We find also, that not only the polishing powder, but the polisher itself, or rather the surface of the polishing tool, must be of different hardness, according to the nature of the substance to be operated upon. Accordingly, diamond is polished on a surface of iron or steel, with diamond dust imbedded in it and a little oil, the various precious stones on Japs of different metals, according to their hardness; glass on pitch, with a large proportion of rosin melted with it, or woollen felt pressed into a firm bed together with the powder; hardened steel and speculum metal on mixtures of pitch and rosin, but that for the latter with a smaller proportion of rosin, 16° Mr Potter on Improvements in casting and working These views led me to prepare the red oxide of iron in the manner hereafter to be described, so that it might have the same relative hardness to speculum metal that the putty pow- der of the shops has to glass; justly expecting, that by means of it as fine a surface might be obtained on the former as is easily prevented on the latter, and thus remove the great ob- stacle which I believed prevented reflecting telescopes, having only the liability to errors of workmanship on two surfaces, which achromatics have on four, besides other disadvantages, from showing a more decided advantage over them. As I here only intend to give what I believe I have learned of better methods than are already in print, I shall point out to the amateur who is only commencing the pursuit, the works where he will meet with information on the subject, and after- wards submit my own observations. He will naturally refer first to the Encyclopedias, and in several of them he will find the greatest part of what he seeks under the heads—telescope, mir- ror, speculum, grinding, polishing, &c.; for specula, he may refer to the original paper of Dr Mudge, published in the Phil. Trans. for 1777, or Mr Edwards’s essay, republished in the Nautical Almanack for 1787; but, above all, he should peruse Sir Isaac Newton’s account, given in his Optics, of the method he followed for the first reflecting telescopes ever made. He will there find the process of polishing described, almost the same as practised at present, in a manner at once instructive and complete, yet concise. As most amateur telescope-makers will wish to have their eye-glasses of their own workmanship, I adjoin a plan of a polishing lathe, which I have used in making the lenses of short focus in my eye-tubes, not having met with any account of a similar one. I have also found it very useful in grinding the small oval specula for the Newtonian telescope, and in grind- ing and polishing small specula for Baker’s original reflecting microscope, which I can here say, for opaque objects, is a very effective instrument ; and I may perhaps, through the medium of this Journal, some day lay before the public the plan on which I have found it most convenient to fit it up. The frame of the lathe is of inch thick deal, the wheel being about twelve inches in diameter, See Plate I. Figure 1, and the Specula for Reflecting: Telescopes. 17 speed pulley having several grooves in it to alter the velocity at will.’ Being thus of sufficient weight, it may be used convenient- ly on the knee in a sitting posture, while with one hand we turn the handle, and with the other manage the working of the Tensin thecup. At a, screwed on the end of the spindle of the _ pulley, is shown the small cup in which the lens is to be ground, it being cemented firmly to the end of a wooden handle as at }, with sealing-wax or gum-lac. It is to be kept continually moving across the cup, backwards and forwards, ‘to preserve a'true spherical figure, which the rotatory motion of the lathe would otherwise soon spoil in convew lenses. In the operation of polishing, the cup having to be coated with ine I have used one of longer radius than the one 1 grind in; thus glasses of ;', inch focus I have polished i in the rind: cup for those of } ined focus, those of } inch in that for those of § inch, &e. pe pursuing this method judiciously, I have no doubt truer lenses of this small size ate‘ to be made than can be by hand alone, and also very much quicker. In grinding ‘specula it is very useful when the metal is tender, which is often ‘the case when they are otherwise good, and these may be ground with the lathe owing to the swift motion, while they would tear up on the face with the emery if worked by hand. With a lathe of the above dimensions, a surface of six to seven square inches may be ground, but-it must then be work- ed on the hones, and polished by hand, the power of the lathe being insufficient for polishing a surface more than one to 1} square inches of either glass or metal. ‘Though the ro- tatory motion of the lathe would spoil the figure of a convex lens or speculum, it may be made use of to give a figure ap- proaching to:an ellipse or parabola in concave ones, and is the method I have pursued in the metals for the microscope, which have a great diameter in proportion to their focal length. In the casting of specula, my experience has been confined to casting about forty to fifty small specula of the oval ones, or the round ones for the miscroscope of } 0z. to 13 oz. each; but I can attest that with the most brilliant metal, viz. 143 parts tin to $2 copper, it requires considerable care and at- tention to get perfect castings even of this size, of good metal, free from contraction, cracks, flaws, &c. NEW SERIES, VOL. IV. No. 1. JAN. 1831. B *» 18 Mr Potter on Improvements in casting and working I have fallen upon one thing in this department within the last few months which I think important, and to attain the same effect a contrary process is generally pursued ; but I have only yet proved it upon small metals, and must leave it to others to determine how far it is applicable to large ones. It is this ; without almost the least hope of its use, I placed in the sand of the moulding box an old steel speculum for the face of an oval one to be cast upon, and the casting was thus chilled as soon as formed. ‘Two cast at the same time in the sand alone, and intended for the microscope, were so tender and rotten as not to bear being ground ; another oval one was better metal, but had flaws in it; but I was agreeably sur- _ prised to find, contrary to my expectation, that the one which had been chilled was the best metal I had ever cast, and so hard and compact that its surface was hardly torn up when I had rubbed off the inequalities on a sand stone, and it polish- ed beautifully. I have cast three others in the same way since, and the metal of all has proved equally hard and good. Experience must teach us the best proportion between the weights of the chilling metal and the speculum, and when of any considerable size, I think the castings will require to be annealed like glass; but we may conclude, that, if annealing enables the metal to bear more lateral strain, it at any rate does not give the property necessary to grind and polish well. I expect that this method of chilling, combined with Lord Ox- mantown’s, of soldering the brittle metal to one of more tena- city, will prove a very useful process for large metals, and re- commend it to his lordship’s attention. I should advise all amateurs, who are only commencing, to get their metals cast by some skilful bell-founder. One whom I employed to cast me two of about 4lbs each, got three good castings out of seven, and I found the metal to work excellently and take the highest polish. By ordering castings of the different sizes you are likely to want, to the amount of 10 or 12lbs in weight, most founders in bell-metal will take the order at 2s. per lb. the price they get in Man- chester being only about 14d per Ib. for the more expensive alloy, bell-metal. The directions should be very particularly given to the founder not to overheat the metal in the melting, and to use, Specula for Reflecting Telescopes. 19 according to Edwards’s plan, a large jit, (or hole through which the metal is poured,) that the castings may be free from holes in the back, by the contraction in cooling, speculum metal being the one which contracts, I believe I may say, more almost than any other. From measurements of the size of a metal of about 5} inches diameter, compared with others of the model it was cast from, I have found the contraction to be about th part of the linear dimension of the model, so that it ought to be made that quantity larger than the metal is wanted ; and in concave and convex specula the radius of the curve must be in the same proportion, as it is easily proved geometrically, by similar triangles, on the supposition of the metal contracting equally in every direction, that a circular are will still remain perfectly a circular arc, but to a shorter radius, in proportion to the contraction. | I believe the most reflective metal to be that of Dr Mudge, viz. about 143 parts of tin to 82 parts of copper. Taking Mr Dalton’s numbers for the relative atomic weights of tin and copper, it appears to be almost exactly two atoms of copper to one of tin. ‘The compound metal has a much greater specific gravity than the calculated one from the proportions ; and this, combined with the consideration of its colour and hard- ness, would have led one to suspect it a binary compound of atom and atom. Of thirty-four specimens which I have weighed hydrostatically at different times, the densities have varied from about 8.6 to 8.98, with often a considerable diffe- rence between different portions of the same castings, which will give an idea that it is a difficult metal to understand the management of. A little arsenic has certainly a great effect in hardening the alloy. Itcommunicates to it the property of beg more sono- rous, and the fracture is also very different. I have only polish- ed two small metals with this addition, and finding no advantage in it, I never use it now. I have found it by measurements not to reflect more light than the same proportions of copper and tin without arsenic. It is.too hard to polish with the powder about to be described, and too soft to take the highest polish with putty, and it has also the character of being more liable to tarnish. | In the working of both lenses and specula,—when they are 20 Mr Potter on Improvements in casting and working small, and the surface is to be flat or but slightly curved,—the form of the handle is of great consequence to insure a correct’ figure. In making some plano-convex lenses, I was for some time unable to polish correctly the flat side, though I tried several contrivances which I thought promised well in theory. I found the only proper form of a handle to bea cone; and for flat surfaces I have used a cone of lead, with the sloping side of about equal length to the diameter of the base, similar to Figure 2, and found it answer well. The only correct way, as is well known, to get a true plane, is to grind together three surfaces, alternately two and two, until they are all alike, when they must necessarily be plane. It is acknowledged to be the most difficult part of the art of the working optician to produce a lens or speculum with a’ good plane surface ; and those amateurs who undertake the Newtonian telescope for astronomical purposes,—if they find _their instrument when finished will not show difficult astrono- mical objects well, may satisfy themselves that it is a hundred ‘to one the greatest fault lies in the small oval speculum not being truly plane ; and this may be told from the figure of the planets, &c. appearing oblong in place of round; but if the eye-glass and metals are not correctly in position with respect to each other, or are what is called out of adjustment, a simi- lar effect will be produced. It is then of the greatest impor- tance in this telescope to have the plane metal as true as pos- sible. I found, however, when the surface had been ground true in the manner described above, and then worked on: a hone very carefully prepared, yet it was very liable to alter some little, particularly near the edges, in the succeeding po- lishing process. This caused me to adopt the following cou- trivance :—For an oval metal of about 1 inch in breadth, and 12 inches in length, I have a circular tool of speculum metal cast of about 21 inches diameter, and about { inch thickness, with a hole in the middle a little larger than the oval, as at Figure 3. Having placed the small speculum in this hole, I make the two hot, and cement themtogether by running gum-lac into the vacancy between them. ‘They may now be ground and polished as one piece, and then the oval removed by heating Specula for Reflecting Telescopes. 21 its back over the flame of a candle, until the cement softens. In this manner, though we grind and polish four times as much surface as we want, yet the small metal is so much more likely to prove a good one, that it is worth more than ten times the additional trouble to follow this method. It is necessary to polish immediately after the tool and speculum have been re- duced to a fine and true surface on the hone; for, if left for some time, the cement is liable, from the different expansion and contraction of it and the metal, to lose its contact, and the two surfaces of metal will be found to be no longer in the same plane. As to what I have before said on the great consequence of having a high polish, it is clear, that whatever may be the power which exists at the surfaces of bodies and produces re- flection,—if the surface be rough only in such a degree that it may require the highest power of the microscope to detect ity—yet a great proportion of the rays of light will be deflected from their proper course, and produce an image, though not palpably incorrect, yet still of a dull outline, and without sharpness. ‘This constitutes what is called a white or silvery polish, but it is what I call only a good approximation to- wards a polish. We have only a good polish when the spe- culum being placed about an inch from the flame of a candle, the surface cannot even then be seen, but appears like a hole cut in the side of aclose box. If metals will not bear this test, is there any cause to be surprised, that, though. they have only one-half the liability to errors of workmanship in- dependent of the incurable aberration of dispersion, telescopes formed of them should still stand second to achromatics ? I have been informed by a gentleman in London, who had every means of knowing it, that some of the cleverest, if not all the opticians there, used putty powder for polishing their specula ; and from what I have seen of the work, I judge it was pro- ' duced with putty on a metal containing a little arsenic. The same person procured for me the direction to a shop where the opticians provided themselves with the article, but I found it, though good, yet not materially different from what I had before used. This putty powder may be procured in the 22 Mr Potter on Improvements in casting and working country from marble masons, glass-cutters, &c. and some drug- gists keep it. Edwards’s direction for making a polishing powder is to calcine the green sulphate of iron (copperas of the shops) ; but it parts very reluctantly with the last portions of its acid, and requires a great heat, and that to be continued for a long time, to get quit of it entirely, and the remaining oxide then becomes too hard. ‘This is readily avoided by precipitating the oxide of iron with an alkali, and then calcining. The best method I have tried is to dissolve a quantity of the sulphate of iron in water, and allow it to stand for a few days, that the impu- rities may settle ; then pouring the clear solution into another vessel, add to it solution of ammonia (volatile alkali), until there is no further precipitate formed ; and, by continuing to add the ammonia until it is in excess, which is told by the strong smell] it gives, we insure that the precipitate is a true hydrated oxide, and free from carbonate of iron. It must now be collected on a filter of muslin and well washed ; then, when settled into a thick mud, it must be put in that state into a crucible covered from the dust, and kept in the fire at a low red heat for ten minutes, when the powder is prepared. For metal which requires a harder powder, it must be kept a longer time heated ; and we may, by this means, have it of any hardness we wish. If there happen to be any carbonate of iron, it will be fotind to corrode the speculum in a peculiar manner in the working, and for this reason ammonia is to be preferred to the carbonates of potash or soda as a precipitant. I have, however, prepared a good powder by precipitating with pearl ash, but it required to be heated several times, and water to be dropped each time upon the red hot carbonate, to reduce it entirely to the state of red oxide, and it had then become rather too hard for my metals. As the progress of polishing out the fine scratches left by the bed of hones is but very slow with the fine oxide, I have for some time followed a plan which I call double polishing, which is, having two polishers prepared with the mixture of pitch and rosin. I first polish with putty, bruising it fine as I want it between two flat surfaces of copper with a little water, on one of the polishers, and then, having the other polisher in Specula for Reflecting Telescopes. 23 a fit state, I finish the metal off on it with the fine powder bruised in the same way. To polish glass, the mixture for the polisher may be } rosin to } pitch ; and § pitch to } rosin is a good mixture for specu- lum metal. The pitch and rosin often contain a good deal of dirt, which renders it desirable to filter them. This is easily done by tying a piece of muslin loose over the mouth of an earthenware jar, and having put the pitch and rosin upon it, placing the jar in the culinary oven. As they melt they pass through the muslin, and give in the bottom of the jar a fine and clean mixture. It is unnecessary with glass to use soap in the polishing, but with metal it is almost indispensible. Soap causes the powder to imbed itself, and also causes the metal to work smoothly without jerks, which jerks are a sign that you are spoiling it. It must, however, be in a state of adhesion, moving stiffly over the polisher, which requires also that you have it neither too wet nor too dry. With putty bruised fine, and used ona polisher hard enough for glass, east steel which has been hardened without being again tem- pered, polishes as well as glass, by taking care to apply con- tinually soap and water in small quantities, for it is otherwise very liable to turn gray in the softer parts of the steel, where the ductility is not entirely destroyed by the hardening process. The amateur, unless he aspires at absolute perfection, needs not trouble himself with thoughts of that bugbear, “a true parabolic figure.” I can asure him that all the most interest- ing objects in astronomy, and many of what are called diffi- cult ones, are to be seen well with a circular curve, when the diameter of the speculum bears no greater ratio to its focal length than is generally used in the Newtonian telescope. In a concave speculum of 53 inches diameter to fifty inches focal length, the difference between the versed sine of a circular arc and the abscissa of a parabolic curve, is only .0000071517 of an inch, or about the 350th part of the breadth of a hair of the head, taking it at the z}, of an inch, which quantity should be worn away from edge of the circular to bring it to the parabolic figure. Will not every one agree that it requires great care and nicety in manipulation to get a circular are true to this quantity ? Hence, to make a fine telescope, the bed of 24 Mr Potter on Improvements in casting and working hones is an indispensible tool, but more particularly for short . foci than long ones ; because the dimension of the emery used in grinding bears a greater proportion to the former than to the latter. " re The ratio of 54 inches diameter of speculum to fifty inches focal length is much greater than prescribed by Sir Isaac New- ton, or used by Sir William Herschel in his seven feet telescope, with which he made the largest number of his discoveries. If we take that proportion, or about 6} inches aperture to 84 inches focal length, the difference between the cirele and para- bola at the edge, or where greatest, is only .0000025146 of an inch, or about 7,45 oth part of the breadth of a hair, or, taking the ratio of distinctness inversely as the area of the least circle of aberration on the retina, arising from this cause, with equal magnifying powers, the seven foot telescope has theadvantage in the proportion of about ten to one. A circular curve may be made to approach towards a parabolic or elliptical one by the method of Mr Mudge, though I must differ from him in some measure in accounting for the manner in which it is effected. After polishing, he allowed the speculum to cool for a few hours on the pitch with a little water about it, and then work- ed it again in a particular manner for a few minutes; and he attributes the resulting parabolic figure to the manner of working, when it appears to me that a great pavt of the effect ought rather to the attributed to the metal having been heat- ed by the hands in polishing, and when cool having contracted again ; it in consequence embraced tightly the polisher, parti- cularly near the edges, and these parts would be the first to be affected by the fresh working. The method I have pur- sued in polishing is as follows:—Having got the bruiser and speculum to the same circular arc on the bed of hones, before commencing the polishing, I warm the bruiser to about 100° of Fahrenheit, and lay it with a little water on the surface of the polisher for a few minutes. The bruiser having expanded with the heat becomes of a longer radius, and communicates the same figure to the polisher ; and when the speculum is ap- plied, the polish proceeds quicker at the edges than at the middle. _ Placing. the heated bruiser on the pitch has a great use in smoothing down any small prominences, which, if they _ Specula for Reflecting Telescopes. 25 were left, would scratch the speculum. To prevent heating the latter, I polish curved metals with a pair of gloves on, that the figure may not be altered during the process. But the difference in the curvatures of the metal and polisher pro- duced as above, is not to the amount necessary to produce.a parabolic figure, even if the working did not tend to retain it a circular one; and yet with no further process, a speculum finished in this manner will show many difficult astronomical objects. I do not think that machinery will be found of any use in polishing specula, or at least those of moderate size. We can- not in this case argue from the manner in which common lenses are manufactured ; for with glass, if you make no pro- gress in the polishing, you at any rate do no harm; but it is. otherwise with metal ; and we are often indebted only to the sense of touch for information, that we are not only doing no good, but also, that if we persist with our work in that state, we shall find it necessary to return to the grinding process again. Believing as I do, that the reflecting telescope is the ‘one with which all astronomical discoveries will be made which require very critical distinctness and defining power, - I feel it incumbent upon me, though the subject is foreign to the immediate purport of this essay, to. remove a very incor- rect idea which is universal in the scientific world on the com- parative illuminating powers of reflecting and refracting tele- _ scopes: It is generally thought that a reflecting telescope with two specula has only about one-half the light that an achromatic one with a double object glass of the same ap- perture has. I am not aware that there is any other founda- tion for this opinion than the experiments of Sir William Her- schel; but though he found very correctly the reflective power of bis specula, he by some unaccountable oversight, or by the unfitness of his photometer, very much overrated the quantity of light transmitted by glass. Having engaged in photometrical measurements of the quantities of light reflect- ed and transmitted by glass, I. soon found that Sir William had made a great mistake ; and that, instead of crown glass ‘transmitting 94.8 rays of every 100 incident, I found, as Count Rumford had done before, that the clearest and best 26 =Mr Potter on Improvements in casting Specula. pieces of window glass transmitted only between 87 and 88 rays of every 100, and of course two pieces would not trans- mit more than about 77, whereas Sir William allowed two. lenses to transmit 89.9. From the great thickness of the glass in achromatic object glasses, there is a considerable quantity lost in the glass besides the reflection at the surfaces, and par- ticularly in the crown glass, on account of the colouring parti- cles it contains. It being hence very desirable to ascertain the actual quan- tity transmitted through an object glass of known excellence, I have here to acknowledge the obligation I am under to Law- rence Buchan, Esq. of Ardwick, near Manchester, for his kindness and politeness in allowing me with his assistance, and that of my friend John Blackwall, Esq. of Crumpsall Hall, whose zeal in promoting science is well known, both of the council of the Manchester Literary and Philosophical Society, to measure photometrically the light transmitted through the double object glass of /his fine and almost new six foot achro- matic by Dollond. From averages.of eight measurements at each point, I found for the centre of the lens the proportion to be 80.93 to 100 incident, for about the middle radius 80.63, and for as near the edge of the lens as possible, safely, 81.92 to 100. These quantities have, of course, to be corrected for the concentrating power of the lens, which I found by the usual proposition for conjugate foci, and also by measurement to be as 10* to 9?, and this gives about 66 rays for the quan- tity transmitted of every 100 incident. This quantity may vary some little in different telescopes, from the different thickness of the lenses, and the goodness of the workmanship ; but taking it in comparison with plane glas. ses, I have very little doubt but that it is very near the truth; and we thus see that an achromatic telescope with one object and one eye-glass has no advantage over a reflector in respect of _ light, with one speculum and one eye-glass of the same quantity of available reflecting aperture, which it has of refracting. And a Newtonian telescope of five inches will have the advantage over an achromatic of four inches aperture in light ; and, who will doubt where the advantage of defining power will be? Mirrors kept with care will retain a long time a reflective 3 ” Mr Grant’s Account of a Male and Female Orang Outang. 27 power of sixty-five to sixty-six of every hundred. The deteri- oration in the small oval speculum i in the experiments detailed in my former paper published in this Journal, cannot fairly be compared with the general usage of a telescope, for it was there of little import spoiling a speculum by hard rubbing, to the ne- cessity of avoiding all risk of being tteeeaved by the least film remaining on its surface. As to preserving mirrors, I have lately adopted a plan for my best small oval ones, which I find will be very desirable with larger ones; itis, to keep them in an air-tight vessel which con- tains a quantity of quicklime, and they will then require very sel- dom any other cleaning than just wiping away the dust with a camel’s hair brush. A wide-necked glass-jar, with a glass-stop- per well ground to it, is a very convenient receptacle for the small sized specula. Smeptey Hatz, 15th October 1830. Art. IIl.— Account of the Habits and Structure of a Male and Female Orang-Outang, that belonged to GrorGE Swinton, Esq. Secretary to the Government, Calcutta. By J. Grant, Esq. Presidency Surgeon, Calcutta. In a Letter to Dr Brewster. Dear Sir, Lone ere this I had fully intended to have followed up. the account of the orang-outang in Mr Swinton’s possession, which you were good enough to give a place to in your excellent Journal; with some supplemental particulars respecting the same animal, and a short description of another that became his companion ; but the pressure of buisness in a climate where the sin of procrastination is too apt to beset one, has occasioned. a delay in carrying my intention into execution, of which a memento in the number of the Journal of Science for October last, brought to my notice by a friend, has made me rather ashamed. Before the receipt of this, you will, I presume, have heard, that the Maharajah, as we used to call the male orang formerly described,* is dead. ‘There is a convenience in designating * No. xvii. Edin. Journal of Science. 28 ' Mr Grant.on the Habits and Structure the creature by this name, which induces me to adhere to it, as it gives a certain individuality to a description. During the year previous to his death, he had grown con- siderably, as may be seen by a comparison of the subjoined with his former measurements. His appearance became much more robust, and he seemed to have assumed a greater degree of boldness and consequence. His teeth at this time equalled in number those of the orang-outang described in Dr Abel’s Voyage to China. The pectoro-laryngeal sacs, too, had assumed that pendulous and pursy form which is conspicuous in Dr Abel’s plate, but was not perceptible when I formerly address- ed you. Within fourteen months of his death, however, they had increased so much, that the collar which fitted him when I first took his measurements, would not buckle round him in its greatest circumference. The following are his measure- ments as taken on the 16th December 1828. Feet. In. * Height from vertex to heel, = < 2.8 Length from the acromion process of the scapula to the end of the middle finger, " i 2 From the top of the sternum to the pubis, - - 1 From the groin to the tip of the second toe, ae | 5 From the wrist to the end of the middle finger, - 0 Length of the palm of the hand, Rs 0 ——— of the sole of the foot from the heel to the end of the middle toe, u # Eve ona From the knee to the sole of the foot % Ne huey: From nipple to nipple, = - : 0 63 From between the eyes to the insertion of the head on the neck, : . “ . 0 83 Greatest circumference of the thigh, : 0 112 Circumference of the foot close to the roots of the toes, 0 Hy round the shoulders, “4 4 2 5 “ This, as compared with his former measurement, give an increase in about fifteen months of siz inches. This leads me to suspect that there must have been an error in my former measurement. Of the accuracy of the last I have not a doubt.—J. G. . To the best of my recollection, he gained three inches in the above in- terval.—G. 3. = of a Male and Female Orang-Outang. 29 Feet. In. Circumference under the arm-pits, - ~i ar @ ; round the loins, is 9 1.68 at umbilicus, : - 1... Mg Greatest circumference of the leg, . * 5S 0 an of the hand over knuckles, 0 — of the head above the eyes, 1 from ear to ear round occiput, 0 73 1 0 0 Greatest circumference round the chin over vertex, Length of the ear, - - - Breadth between eyes, = . - 1 From the symphysis to the ramus of the jaw, - 0 5} Length of the arm from the acromion process of the scapula to the olecranon, - - 0 2 From the elbow to the wrist, a y dive Z From the tip of the thigh to the knee, - -, 0 3 From knee to heel, d - - - Oe 5/% Length of perineum from the scrotum to the verge of the anus, “ *. 0 2§ Weight (taken in September 1828) thirty-five pounds six ounces, Avoirdupois, giving an increase in a twelvemonth of thirteen pounds, six ounces. At this time he had twelve teeth in each jaw, viz. six double teeth, four incisors, and two canine. Ina state of confinement the orang-outang appears to be subject to obstruction of the bowels, the consequence, proba- bly, of want of exercise, and of the fruits and other food he feeds on in his native woods, and sometimes, as in the human subject, of dentition. Early in December 1828, the Maha- rajah was taken ill, and, as he was cutting his two last molares at the time, the irritation arising from this was, in all likeli- hood, the cause of his indisposition. It being pretty obvious at any rate, that he was suffering from constipation, some cas- tor oil was offered to him, but he refused to take it. He was then laid down on his belly, and, with a Reid’s patent syringe, an enema, consisting of castor oil and spirits of turpentine, with some warm water, was administered. This operation he submitted to with comparatively little resistance, considering ‘its novelty. In this way nearly two quarts had been thrown 30 Mr Grant. on the Habits and Structure up and retained, but not producing the desired effect, he was put into a warm bath. He submitted quietly to this also, and seemed to enjoy the’ pleasant warmth. After removal from the bath, and having been carefully wiped and dried, another enema was given. The repeated administration of the remedy, to the extent of several quarts, brought away a large quantity of indurated feces, the evacuation affording evident relief. Eight grains of calomel were then given him in some milk, and he was allowed to wrap himself up in his blanket to take his repose. During the night, he was again copiously moved, and at day-break was sufficiently recovered to leave the bed which had been made for him in one of the rooms of the house, and to go to his own usual place of abode. All that day he evinced a disrelish for food, appeared languid, and retired early to rest. In the course of a few days, he seemed as well as ever. Independent of the humane design of relieving the poor creature from suffering, it was of considera- ble importance to preserve the animal’s life if possible, for the purpose of solving an interesting zoological question. Those who perhaps may be apt to smile at any thing like a particu- lar reference to the ailments and medical treatment of a spe- cies of monkey, should bear in mind that the diseases of ani- mals, no less than their appearance and habits, merit the at- tention of the student in natural history, and ought not, there. fore, to be overlooked when opportunities occur of properly adverting to them. During the illness of the Maharajah, the woeful expression of his countenance very much resembled that of a human pa- tient, and made the natives around him apparently forget his order of being. Indeed it was amusing to observe them while the enema was being given, coaxing and speaking to him in their language, as they would to a sick child, stroking and soothing him with—* Rajah Sahib! Rajah Sahib! Gen- tly now Rajah Sahib !” when the creature happened to be a little restive or impatient. I have now to introduce to your acquaintance another in- dividual of the * orang outang kind, which arrived in Calcutta * This is the animal of which a notice has been given in he Journal for October 1829. of a Male and Female Orang-Outang. 31 in the early part of 1828. She (for the creature was. consi- dered a female) had lived with a family at Singapore for up- wards of a twelvemonth, and was accustomed to play with the children. Her disposition was remarkably mild, and she had been taught to stand upand walk erect,—a position, which, in Calcutta, she frequently and habitually assumed of her own accord. She was procured from the family alluded to by Captain Hull of the Bengal Military Establishment, who presented her to Mr Swinton as a companion for the Mahara- jah. Like him, she soon obtained a name, and was called the Rannee. It would be quite superfluous to enter into a mi- nute description of her appearance, since the account of the Maharajah in most particulars will apply to her. She seem- ed much of the same age and height, but more slender, and her features and limbs were more delicately formed. ‘The hair of her head was of a finer texture, and her eye-lashes were larger and of a more silky appearance. The following is a memorandum of her measurements taken at the same time as the Maharajah given above. Feet. In.’ Height from vertex to heel, ‘ i Q 65 Length from the acromion process of scapula to end of middle finger, - 2 2 12 From the top of the sternum to the pubis, - ye From the groin to the tip of the second toe, 1 From the wrist to the end of the middle finger, 0 1 Length of the palm of the hand, i saletige piraatt 7 Length of the sole of the foot from the heel to the end of the middle toe, . # ee From the knee to the sole of the foot, ts ac... From nipple to nipple, siti . 0 7 From between eyes to the insertion of the head on the neck - . - | Ry ee Greatest circumference of the thigh, 0 9 of the foot close to the roots of the toes, = " - 0... .68 Circumference round the shoulders, ° Sue under the arm pits, - 1 Allg round the loins, - - 1 4 at umbilicus, at s eg 32 Mr Grant on the Habits and Structure Circumference above umbilicus, - - 1 Greatest circumference of the leg, - y 0 g of hand over knuckles, - 0 of head above eyes, - aiid from ear to ear round occiput, 0 68 round the chin over the vertex, I & ‘Length of the ear, - - Oe. 1¢ Breadth between eyes, rt t peg From ramus to symphysis of the jaw, . From acromion process to the olecranon, & 0 0 0 From elbow ‘to wrist, - - 0 é 0 0 0 From tip of the thigh to the resea - - From knee to heel, s mn L Perineum, ¥ Weight (taken in Sipretiber 1828,) twenty-nine pounds four ounces, Avoirdupois. From the above, it appears that her limbs, in comparison with the head and trunk, were longer than the male’s. Her hands too were longer, but her feet shorter. In walking she appeared rather taller, in consequence of her being actually more slender, and from holding her head and person much more erect than the Maharajah. She had ten teeth in each jaw, viz. four incisors, two canine, and four double. Her sex for a time was rather questionable, some asserting that it was a male. Careful examination, however, which was afterwards proved by dissection after death, showed that the creature was really female, with the external organs of ge- neration defectively evolved, an accidental circumstance, it is to be presumed, peculiar to the individual. Like the greater number of young female orangs that have been noticed, she had no nail on the great toe of either foot. During the examination as to sex, the poor creature appear- ed to be excessively alarmed, moaning and crying in a pitiable manner, although of course she was handled as tenderly as possible under the cireumstances. The appearance of the ex- ternal organs, as stated already, was rather equivocal. There was no vulva, and a small penis-like body hung flaccid at the usual place. That it was, however, not a penis, became obvi- ous on finding that it was imperforate and without a prepuce. of a Male and Female Orang-Outang. 33 On raising it there appeared within about half an inch of its root, a small round opening, scarcely large enough apparently to admit the end of a common bougie, and through this the urine flowed. Whether this, however, was the proper urinary passage, or a common canal leading to a vagina and urethra, was a point not to be determined during the life of the ani- mal. } Some curiosity was naturally entertained to observe the re- sult of the first interview between her and the Maharajah. On her part, the timidity natural to the female sex marked her whole demeanour. His was less reserved, and he display- ed an inquisitiveness evidently repugnant in some cases to her delicacy. Neither on this occasion, however, nor any other during their domestication together, did he ever evince the slightest indication of sexual passion. Although they often played and wrestled together, they never quarrelled, but always continued on excellent terms. The Rannee appeared conscious of her inferior strength, and, as the weaker vessel, generally gave way. It is but justice, however, to the memory of the Maharajah to declare, that he _ paid her the deference due to her sex. Even in the article of food, if she chanced to get first possession, he never would snatch it from her. In this respect, biographical veracity con- strains me to state, that she seemed: to be more selfish, evin- cing but little disposition to share with him whatever she could manage to appropriate entirely to herself. For instance, dur- - eing his illness, she appeared at first to sympathize in his suf- ferings, sitting beside him and bestowing the orang kiss. This she did by projecting her lips in the shape of a hog’s snout into his mouth, a caress which was kindly taken; but the night being cold, she afterwards rather unfeelingly strip- ped him of his blanket, as an additional covering for herself. She appeared, too, to be more mischievously inclined than the Maharajah, and somewhat foolishly so, for it was her great delight to untie the ropes attached to the top of some high poles fixed in the ground to afford them the exercise of swinging, of which both were exceedingly fond. No sooner had the ropes been again tied with all the knots that Gordian ingenuity could devise, than she would clamber up to the top NEW SERIES, VOL. IV. NO. I. JAN. 1881. : c 34 Mr Grant on the Habits and Structure of the pole, and never desist until with teeth and fingers she had disengaged them. While she was thus occupied the Maharajah would exhibit himself to the native spectators, whom his appearance was wont to attract daily in a crowd round the gate. Occasionally he would catch hold of some individual and unloosen his cummerbund or girdle cloth, in the corner of which the natives usually tie up their copper pice or half- pence, and the bettel which they may keep for chewing. Of - this part of the office of the cummerbund he was perfectly aware, and when once master of the cloth, would set himself deliberately to untie the knot at the end of it, and extract the contents. These, whether pice or pawn, * he would imme- diately transfer to his own mouth. ‘This petty larceny was usually gone through with the greatest solemnity of manner, which heightened the effect of the scene, and afforded infinite amusement to the admiring crowd. The Rannee never at- tempted to take purses in this direct and open manner; and if not engaged in swinging at the time, or untying the swing rope, would take her station on the top of the gate, quietly looking on while the Maharajah was levying his contributions as stated. As soon, however, as he had succeeded in making himself master of any booty, she would hasten to aid him in examining and tasting the articles. For many months before, our satyrs had never been chained, but notwithstanding they evinced no desire to run away. During the mornings and evenings they were allowed to play in the Compound or Court yard, and the gate was their favourite lounge. In the middle of the day, to protect them from the excessive heat, they were shut up in an outer house adjoining the place where the palanquin bearers resided, and found amusement in clambering up and down the bamboos which were nailed up in front to prevent their getting out. Their diet was extremely simple, consisting of fruit. and. milk. The Rajah was fond of wine, particularly champagne, also of country beer, + and of all spirituous liquors, which the Rannee, on the other hand, would not taste. | * A kind of condiment which the natives are very fond of chewing, © composed of bits of areca nut, cloves, and chalk, wrapt up in a double fold of bettel leaf so as to form a small triangular packet. + An Indian hot weather beverage, somewhat resembling ginger-beer. of a Male and Female Orang-Outang. 35 Their disposition was mild and docile, and they never at- tempted to bite, but were apt to take one’s hand in their mouths as a mode of testifying kindness ; and with children they were uniformly gentle. The Rannee frequently walked in the erect posture. The Rajah ‘did so but seldom, always preferring to swing himself forwards, resting on the back of his hands and wrists, or vaulting over on his head in a succession of so- mersets. In January 1829, the Rannee was taken ill, apparently with a cold and defluxion of the lungs. Gradually the cough (which was attended with quick pulse and fever) got worse, and she grew daily more emaciated. She appeared very sensible to the effects or alternations of external temperature, and for the most part would remain in a recumbent position under a blan- ket. Various remedies were tried, but they were of little avail, and the poor creature died in the month of March following. The body was examined in a cursory manner by my friends Mr Breton and Dr Adam, and myself. We were much struck with the strong resemblance of the viscera generally to those of man. The cause of death was very extensive inflammation, followed by considerable adhesion and effusion in the thorax and abdomen. ‘he urinary and generative system underwent a minute examination. A director having been introduced ito the external aperture, an incision was made carefully upon it down the perineum. ‘Two orifices then became visible, and the canal of each was traced to its source, the upper one lead- ing to the bladder,.and the other to the uterus. © The latter or vaginal canal was evidently dilatable ; im its undilated state it was large enough to admit a common pencil case. It was about an inch in length, and the blunt probe introduced along it was felt with the finger in the ‘cavity of the pelvis, where it met with obstruction to its further progress from the os tince. Owing to the smallness of the parts, it required some little trou- ble to demonstrate them, but the existence of the uterus, with its Fallopian tubes and ovaries, was satisfactorily exhibited im the end. After this hasty inspection, the remains were put up in,spirits and forwarded to the Zoological Society of London. The Maharajah was not long destined to survive her, for on the 26th of June 1829, he also died. During the six months — 36 Mr Grant on the Habits and Structure immediately preceding that event, he had had repeated attacks of fever, which were not ushered in, as far as could be judged, by any rigors, and the poor fellow in consequence gradually wasted away. At times he seemed to be free from feverish symptoms, when he would appear to revive, and resume his accustomed food of plantains and milk. For the most part, however, he lay down in a languid state, and evinced what in him appeared a most unusual degree of sluggishness. Mr Breton informs me that a quantity of loose green-coloured paper lying about his room, (for on his illness he was removed to Mr B.’s house,) such as is used for making pamphlet covers, &c. the Maharajah several times gathered them up and cover- ed himself completely over with them. Did their green colour and lightness lead him to suppose that these pieces of paper were the leaves of trees? or may we infer from the above fact, that when they feel cold, orang-outangs, in a state of nature, cover themselves up with the leaves of trees? During his ill- ness calomel, castor oil, and enemas were occasionally given, and they always seemed to afford relief. You will easily imagine how disappointed we all felt at a circumstance which completely frustrated an expectation we at one time had entertained, that this orang-outang might be des- tined to solve the interesting question, whether it. was a young one of the gigantic race, of which an individual was killed on the island of Sumatra by Captain Cornfoot’s party ; * or of a smaller species, supposing the orang proper to consist of a Patagonian, and a middle sized, or pigmy race? ‘This question, it is to be feared, cannot be set at rest unless the observer was stationed for a sufficient length of time at Sumatra or Bor- neo, where the animal would enjoy its own native climate ; since it is pretty well ascertained now that it cannot live long in any other. Mr Breton, Mr Egerton, and myself examined the bed of the male orang, but I cannot aver that the autopsy gave us a greater insight into the cause of death than we had before. The creature had literally pined and wasted away under a spe- * Asiatic Researches, vol. xv, and Edinburgh Journal of Science, No. viii. 3 of a Male and Female Orang-Outang. 37 cies of irritative fever, attributable most probably to general insalubrity of climate. There were no signs of high and ex- tensive inflammation, and no traces of a as in the ease of the female. A good outline of the anatomy of the plengteratatig: as far as it goes, is to be found in an account of the dissection of one by Dr Jefferies of New York, * which tallies in almost all re- spects with what we observed in the one under consideration. In a climate like this, (the thermometer in the dissecting-room stood at 90°,) where animal matter proceeds with the utmost rapidity to a state of decomposition, zootomical research must always labour under great disadvantages, for which due allow- ance ought to be made. ‘The thorax having been laid open by an incision through the sterno-costal cartilages, and the sternum reflected back, the pericardium was exposed to view. This having been pierced, about two ounces of sanguineo-serous fluid flowed out —the pericardium having been slit up, an opening was made into the left ventricle of the heart, and the arterial system filled with common wax (red) injection. A dark’ injection having been prepared for the venous system, the nozzle of the syringe was introduced into the vena cava superior, and the fluid forced up. Unfortunately, however, the parts were ruptured in course of the operation, so that a great portion of the hot injecting ingredients escaped. This accident had not happened before the manifestation at the median vein (laid ‘bare for the purpose) of the partial success of the process. As the subject, however, was becoming every moment more and more decomposed, we determined to lose no more time in injecting, so that we did not middle with the inferior venous system. | We next proceeded to open the head. Thedura mater was found remarkably thick and strong, much more so than in man, nor was it apparently the effect of disease, but the na- tural state of the structure. On slitting it open, a little ve- nous effusion was found between it and the pia mater. The méningeal artery having received a full complement of the in- jection, made a beautiful arborescent appearance. Reflecting * See New London Mechanics’ Register, vol ii. of Second Series. 38 Mr Grant on the Habits and Structure back the meninges, we examined the longitudinal sinus, and found it filled with the black injection. The appearance of the brain was on the whole very human, but it did not exhibit by any means so many convolutions as in man. It was rather high at the coronal region, but fell off as compared with man at that part of the sinciput which phrenologists term the re- gion of causality. The corpus callosum was well developed, but no raphé was observed. The choroid plexuses were very large, and well marked. The torcular herophili was found injected with the black fluid, which is a rare occurrence in the human subject. The different ventricles were distinct, as were the corpora quadragemina. We looked most care- fully for the pineal gland, but there was none to be found, and whether this be generic or an individual peoulisraty we could not determine. The usually rough seat of the gland was found perfectly smooth. In Dr Jefferies’s subject, unfortunately, the brain was not dissected, so that we can derive no analiate Tight) iften that quarter. _ The nerves rise from and leave the orang brain in the same way asin the human, and are similar in appearance. The optic nerves were large, and the pathetics very small, resem- bling the finest white silk thread. The circle of Willis was found beautifully injected, and had a most human appearance. The same observation applies to the pons varolii, the erwra cerebri, the medulla oblongata, the basilar artery, and the in- ternal carotid generally. ° The cerebrum throughout was very firm in its texture. There was not such a marked distinction, we thought, between the medullary and cortical substance as in man. The former appeared to predominate more than in man, and to be of a more clayish hue. ‘he cerebellum was very soft, and the arbor vita, consequent- ly, somewhat indistinct. The cerebrum and cerebellum to- gether, detached from their membranes, weighed eleven’ ounces and a-half, from which, perhaps, half an ounce may be Mesum ed, on account of the injected matter. The abdomen, as in Dr Jefferies’s subject, presented a view so similar to the human, that it required some attention to note : 3 of a Male and Female Orang-Outang. 39 any peculiarity. The stomach, with its well-defined pylorus, was in situation and figure like that of man. The arch and sigmoid flexure of the colon, with the caput caecum, and the vermiformis (four inches long) very much re- sembled the human. ‘The liver, spleen, and duodenum were also in appearance very like the human, but smaller compara- tively, especially the spleen. The cystic and hepatic ducts were very distinct, until they became, as in the human subject, a common canal entering the duodenum. ‘The organs of generation and of urine (includ- ing the kidneys) were also similar to the human, but smaller. The testes had not descended into the scrotum, and the sper- matic artery was very small, and had received none of the in- jected matter. The thoracic viscera bore the same striking general resem- blance to those of man that the abdominal and cranial did. The breast was much smaller than one would expect it to be in a child of three or four years old. The chief superior ar- teries arose from the aortic arch, as in man, but the whole ar- terial system seemed on a more reduced scale, the aorta throughout not being so large as in a human child. The lungs, too, did not appear to be so distinctly lobulated as in the human subject. The mouth resembled the human organ in a less degree than other parts of the animal. Its snout-like projection gives a more acute facial angle than is to be found in a human head, save in the lowest of the species, as the Carib Indian and the New Hollander. The dimensions of the mouth are also much greater than in man, to say nothing of the peculiar action or appulse of the lips, which is never witnessed in the most wild human savage. The colour of the roof of the orang mouth, too, (at least of the subject under consideration) is dark and not red or reddish flesh-like asin man. There was no uvula observable. The glottis, epiglottis, pharynx,and the os hyoides, with its connections, were much the same as in man. ‘Two valve-like apertures leading into the pectoral sacs of Camper, are situated in the larynx, between the os hyoides and the thyroid cartilage, and were large enough to admit the end of a full-sized bougie.. Through these passages the animal in- 40 Mr Grant on the Habits.and Structure flates these pouches at) pleasure; for what purpose * is as yet a matter of uncertain speculation, unless it be, as Dr Jefferies surmises, to assist in supporting the animal when swimming,— a species of exercise, by the way, which the creature, I should imagine, ean scarcely be much called upon to have recourse to, since neither Sumatra nor Borneo, I believe, affords large rivers or lakes for such a purpose. The pectoro-laryngeal sacs extend from under the chin, from the edge of the platys- ma myoides and skin on each side, down the neck and over the breast, and in the full-grown gigantic orang must be of enormous size. The anatomy of the axilla much resembled the human in every respect, in the course of the artery and vein, and the disposition of the meshes of the nervous plexus. ‘The submaxillary glands were of an enormous size, ach more so than in the human subject. The anatomy of the heart and aorta is extremely. like the human; and the great systematic trunk gives off its visceral branches in the abdomen precisely in the same manner. The femoral artery high up gave off the profunda as in man, then pursued it course as a large trunk, and above the knee divided into two large branches ; one being not a ramus an- astomoticus magnus, as in the human subject, but the tibialis anticus, which gives out branches to the knee-joint. The other large branch, or more properly speaking, the popliteal, after running two inches and a-half, divided into the posterior tibial and interosseous, giving off small branches to the muscles. Of the animal’s osseous structure, I need say nothing, even if I had a sufficiently long and convenient opportunity to consider and reflect duly upon it, which I had not. The bones, however, have been sent to the Zoological Society of London, where, no doubt, they will attract the attention of competent judges. It is to be hoped that the illustrious Cu- vier may have an opportunity of comparing them with those of others of the Simia satyrus race; more especially, the skele- ton of Wurmb’s Pongo, which is, if I recollect right, still pre- served in one of the Royal Museums of Paris. © Has the frog any sacs of this kind? The croaking sound given forth by the orang-outang is very like that of the frog. of a Male and. Female Orang-Outang. 41 Of the exact age of the animal, I possess no decisive data. Its great youth was manifested by the general appearance of the teeth, and of the bones, &c. The roots of the upper molares were only about half-formed ; * and the cartilaginous epiphyses of the bones, the non-descent of the testes, and the absence of sexual desire, irrefragably demonstrate its infantile adolescence. But whether its age was between four or five, or seven and eight years, I really cannot take it upon me to say. From the formation of the teeth, the animal would appear to be omnivorous. In its docile state, it readily eats meat; nor do I conceive it to be a very violent conjecture that, in the wild — state, it may at times prey upon the lesser animals and birds. Indeed, I suspect that there are few quadrupeds that could resist the: attack of a gigantic orang like Captain Cornfoot’s. As is the case with other Simie, they are, perhaps for purposes of mutual convenience and protection, gregarious. On a fors mer occasion, I,adverted to the testimony of M. Foucher D’Obsonville, who states, on information procured on the spot, (at Sumatra,) that the orang-outangs wander in the woods, or upon mountains of difficult access, where they live in small so- cieties, and take precautions for their subsistence and defence. Nor is it improbable to suppose that they live in pairs. It would, indeed, be most interesting if we could trace them to their secret haunts, and get accurate ideas of their general and domestic economy. We might then be able to determine whe- ther, like foxes and other animals, orang-outangs are genuine troglodytes or not; whether, like the beaver, they construct habitations for themselves, seeing that nature has given them hands to execute, if not sagacity to contrive; whether, like the field-mouse or the ant they lay up stores of food; whe- ther the males are polygamists, or otherwise; whether the fe- male, at the time of bringing forth her young, retires to any particular place; and whether, in that state, she is looked af- ter, and supplied with food and drink by the male, or allowed to shift for herself ; whether the old and decrepid are allowed » to perish from neglect, or, as has been witnessed among rats, they are tended by others of the community ; whether, sup- posing them to have a particlar cave or habitation, they remove * The incisores and canine teeth ‘were permanent. 42 Mr Grant on the Habits and Structure the carcases of the dead, and what do they do with them; or whether, upon a casualty, they remove to other quarters, thus leaving the dead as ina tomb? In short, what are the habits of the animal in a state of nature, seeing that of its private history we absolutely know nothing? That they have some sort of habitation or other, is no difficult point of belief, since we have analogy for it; and that they generally betake themselves to such secret places as caverns, or hollow trees, to die in, I am inclined to think evinced by the circumstance of their bones or carcases being seldom or ever found, at least so far as I am aware. If the creature possesses no higher in- tellectual powers than the other wild denizens of the forest, of course, his habitation or den, or whatever it may be, will afford no evidence of ingenuity or forecast ; since a higher degree of | intelligence than his other sylvan neighbours would be thrown away upon him. é . Orang-outangs, it has been résivened awk exhibited no greater degree of intelligence than a dog. ‘ This, generally speaking, is, I believe, a correct enough observation, but then let us bear in mind the comparative advantages, in relation to his connection with human society, that the dog possesses over the orang-outang! Companionship with man is to the dog a state of nature and gratification; he is * to the manner born.” Not so the poor orang-outang ; left, perhaps, when an infant or very young, and unable to provide for itself at some spot, while its mother wanders in-another direction, with the mten- tion of returning by-and-by to lead him home. A Sumatran or Bornese forester passing that way swoops him off; and the little creature that had been accustomed to active gambols in the wild wood, (to say nothing of change’of diet, and climate, and water,) is henceforth transferred to, and confined to a small inclosure, where its movements are circumscribed, where he is perhaps chained; and never like the dog, solaced with the society of its kind; where, in short, his whole system and habits must undergo a change consequent on slavery; and where its faculties have not their fair field for developement. How is it to be expected, under such circumstances, that an orang-outang child (for all the orangs to descriptions of which I have had access, were supposed to be very young,) of a Male and Female Orang-Outang. 43. should be more intelligent than the most intelligent of all the inferior animals, the full-grown dog, in the prime of his facul- ties and strength, naturalized’ to a state of connection with hu- man society, and unhappy save under such circumstances ? The orang-outang, however, without being taught, will do what a dog, I suspect, cannot be taught to do, and untaught, cannot think of doing: he will untwist or unravel his chain or cord. If the dog’is chained, and the chain becomes in any way jammed between things lying about, or twisted upon itself, the animal drags hard at it, away from the point of entanglement, perhaps increasing the evil,—becomes alarmed—cries out, and never thinks of slackening the chain, and returning back to see what the cause of the inconvenience is. Not so the orang- outang; the moment such an accident occurs, he deliberately sets about putting matters to rights. He does not drag away from the point of resistance, does not insist on running forcibly: counter, but instantly slackens his chain, as a human being would do under the like circumstances, and goes back to see what occasions the obstruction. If the chain has got entangled with a box or any other article of furniture, he disengages it ; if it has become twisted, he considers the matter, and untwists it. It may perhaps be said in reply, that the possession of hands gives the orang advantages that the dog has not, in the instance referred to, and so undoubtedly it does ;..but it is not natural for an orang to be chained, and the whole process evinces that he thinks or reflects upon the predicament he has got into, which the dog apparently does not, but looses his presence of mind. I havea monkey chained in my compound, (Simia entelius,) but when his chain becomes entangled or _ twisted, he does not get himself out of the scrape like the orang- outang, but, like the dog, makes matters worse by dragging impetuously. Will you permit me, with due deference to the opinion ex- pressed in your note upon my former communication, once more to touch upon the question of the orang-outang’s mode of progression? The anatomical structure of the tribe, it is stated, precludes the possibility of their walking erect. Surely their going erect in a state of confinement sufficiently answers the question as to possibility? Then again, with reference to Ad. Mr Grant on the Habits and Structure the fact cited of the gigantic orang-outang killed by Captain - Cornfoot’s party having been seen to move erect with a wad- dling gait ; it is to a certain extent very justly observed in your note, that ‘* many of the mammalia, when acting on the de- fensive,* rear upon their hinder legs, or sit upon their haunches; and it was quite natural for the large specimen killed by Cap- tain Cornfoot, to approach his assailants in the erect position, this leaving, besides his teeth, his two arms free, to be used for his protection.”—-Now, my dear Sir, if you will refer again to ‘the passage, you will observe that the animal was running away from his pursuers, so that his teeth and arms at the time were not in a state of defence’; his attitudes altogether was one of sheer escape, not of defence or resistance, the position of all others which he was in on level ground, when running for — his life, being the erect one! True Dr Abel observes, that * his motion on the ground was plainly not his natural mode of progression.” This, however, has not, I think, been quite demonstrated. - I admit that the climbing, bounding, or sitting attitude, is the most natural one of the creature among trees ; but when he has to travel over a level surface, between copse and copse, or clump and clump, I do not think it has been unanswerably made out, that the erect is mot his natural mode of progression. At any rate, my wavering notions on this sub- ject have been rather confirmed since I made my former com- munication, by a similar leaning of opinion on the fact of Mr Breton, and other scientific friends, as well as by some re- marks apposite to the subject made by Dr Jefferies in the paper already alluded to, no less than by what I have wit- nessed of the movements of several gibbons. The orang- outang, however, does not so much walk as shamble onwards, the knuckles of its long arms resting on the ground, forming as it were crutches for his body to swing between, so that the body is always very nearly erect.. The long armed gibbon, again, rarely ever goes, except quite upright; it ismerely when he wants to move a pace or two'only, that he swings between his hands; when he means to go several paces he stands up and runs. But, remarks Dr Jefferies, with respect to the orang- ’ * The common brown bear for instance, or, to come to a more familiar illustration, the common goat. of a Male and Female Orang-Outang. - 45 outang, ‘ the articulation of the femur, with the aceta- bulum, is almost exactly like man’s; the neck of this bone forms about the same angle. In quadrupeds this fornis a distinguishing characteristic, being in them nearly a right angle. The inspection of this joint is alone sufficient to satisfy a naturalist, of at least the facilings if not the natural disposi- tion, of the satyrs,; to walk erect.” Although the orang-ou- tang and the gibbon, however, can certainly proceed for a con- siderable or given distance in the erect position, it is evident, that they could not, like man, keep up that mode of’ progres- sion for many hours, or to a great distance over level ground, save with most fatiguing exertion and many halts on the way. All the orangs and gibbons I have seen proceed in the erect position, always impressed me with the idea that they did so; somewhat in the manner of a child when it first learns and essays to walk, moving rather oneal forward, as if afraid to fall. The patella of the ditbipbeiinany is like that of man, as is indeed the whole knee-joint. The ankle is also like the hu- man, and the os calcis is broad, and sufficiently projects be- hind to support the erect posture. Dr Jefferies, from a view of the whole structure of the individual described by him, notes the peculiarities which he deems will enable us to form an opinion of his natural mode of progression ; and with these, permit me to conclude what I apprehend you must think a very rambling, ime and un- satisfactory communication. First, Going on all-fours, he would find inconvenience from the elbow-joint ; for, when the hand is placed upon the ground flat, the flexion of the joint would be contrary to that of qua- drupeds, by bending back towards the body instead of forward, which would rather impede than assist progression. It is not, however, as difficult for the safyrus to turn the joint forwards as it would be for man, on account of the curvature of the bones of the fore-arm, and the free motion which existed in all the joints. The roundness of the chest, and the scapula sitting so far back, would make it difficult for him to bear weight upon the 46 Mr Grant on a Male and Female Orang-Outang. hands. Quadrupeds have * the chest flat, and the scapula far forwards upon the ribs. The articulation of the hip would make it more easy for him to go erect, on account of the little angle made by the neck with the body of the femur. Secondly, In walking erect he would derive advantage from the extension of the os.caleis and the length of the foot ; and also from the position of the arms so far back, and from their length, which would enable him to balance the body by them. Thirdly, From the structure of the viscera, he seems to be peculiarly formed for an erect posture. The pericardium being united extensively with the diaphragm, would prevent it from being drawn down by the weight of the liver and abdominal viscera. In quadrupeds this is not necessary, for the pressure of the abdominal contents assists expiration ; and, if the pericardium: ‘was attached to the dia- phragm, as in the satyrus and in aan, ‘inspiration wont be impeded. ‘ The exit of the spermatic ici is another difference from quadrupeds. It does not pass out directly from the abdomen as in the dog, but perforates the peritonzeum and muscles ob- liquely, as has been described, thereby giving that admirable — structure to fortify the groin from rupture, which exists im’ man. The viscera of the abdomen were suspended to bear weight in the erect posture, particularly the Hg which had its wat ments very strong. ; ‘From these and other circumstances, apparent miei an exa- mination of the skeleton, I think we must conclude the ereet . posture to have been most natural. At least, if it is humiliat- ing to dignify him with the title of a biped, he stands acquit- - ted from that of a quadruped, from the peculiar formation of his lower extremities. We must then denominate him, as true © naturalists have done, a quadrumanous animal.—TI remain, &c. Caucurta, Are J. Grant. May 8th, 1830. * That is to say, I presume, the sides of the chest. Dr Graves on the ‘Ankle-joint of the Horse, &c. 47 Arr. 1V.—An account of a Peculiarity not hitherto described in the Ankle, or Hock-joint of the Horse ; with Remarks on the Structure of the Vertebre in the Species of Whale, en- titled Delphinus Diodon. By Roser J. Graves, M. D., M. R. I. A., King’s Professor of the Institutes of Medicine, _ Honorary Member of the Royal Medical Society of Berlin, of the Medical Association of Hamburgh, ‘&c. &c. * Bere engaged in the dissection of the horse, on examining the hock-joint, I found that any effort to flex or bend the limb at that joint, was counteracted by a considerable resistance, which continued until the limb was bent to a certain extent; after which, suddenly and without the aid of any external force, it attained to its extreme degree of flexion. In attempting to re- store the extended position of the limb, I found that a similar , impediment existed to its extension, until the same point was passed, when the limb suddenly, as it were, snapped into its extreme degree of extension at this joint. At first I conceived that this phenomenon depended on the tendons of the flexor and extensor muscles of this joint; but _ on removing all these muscles and their tendons, it was not di- minished, and. it therefore became clear that it depended on, some: peculiar mechanism within the joit itself. Before I enter into the details of this mechanism, it is neces- sary to remark, that it is evidently connected with the power this animal possesses of sleeping standing, for it serves the purpose of keeping the hock-joint in the extended position, so far as to counteract the oscillations of the body, without the aid of muscular exertion; and in this respect it resembles the provision made to effect a similiar purpose in certain birds, as the stork, and some others of the grallz, which sleep stand- ing on one foot. It will appear also in the sequel, that not only is the effect produced the same, but the mechanism is in many respects similar, if the account given by Cuvier, and also by Dr. Macartney, in Rees’s Cyclopedia, article Birds, be correct. Sheep and cows are not provided with ankle-joints of a si- * From the Royal Irish Transactions, vol. xvi. Read July 5, 1830. 48 Dr Graves on the Ankle-joint of the Horse, milar structure, and it is well known that these animals do not possess the power of sleeping standing. Another circumstance which adds additional interest to this peculiarity of structure, is, that it may possibly be connected with the disease termed String-hailt, in which the limb is at each step suddenly flexed, to a degree far beyond that required in ordinary progression. Whe- ther this is owing to a sudden and jerking flexion of the whole limb, or to flexion of the hock-joint alone, I have had no oppor- tunity lately of determining. If the latter be the case, it is pro- bably connected with the structure of the hock-joint, which I am about to deseribe. It may be right to observe, that not even a probable conjecture has been advanced, concerning the na- ture and cause of string-halt, a disease to which the sheep and cow are not subject, and we have already observed, that in these animals the structure of this joint presents nothing re- markable. The hock-joint is a good example of what is termed the hinge-like articulation, and is formed between the tibia and astragalus, which latter bone presents an articulating surface, with a nearly semicircular outline, and divided into two ridges, including between them a deep fossa. The tibia is furnished with depressions which ride upon the ridges of the astragalus, and has anterior and posterior projections, which, moving in the fossa, are received into corresponding depressions ~in the astragalus, at the moment the limb arrives at the ae de- gree either of flexion or of extension. The shape of the surfaces of the astragalus concerned in the articulation, is not that of a given circle throughout, for towards either extremity, the descent is more rapid, or, in other words, answers to an arc of a smaller circle. Hence, when one of the projections of the tibia has arrived at its correspond- ing cavity in the astragalus, which happens when the limb is either completely flexed or completely extended, the rapid curve of the articulatmg surface presents a considerable ob- struction to change of position. Thus, the form of the articu- lating surfaces, in itself, to a’ certain degree explains the phenomenon, but its chief cause is to be found in the dispo- sition and arrangement of the ligaments. The external malleolus of the tibia is divided by a deep and the Vertebree of the Whale. 49 groove, forthe passage of a tendon, intoan anteriorand posterior tubercle; from the latter of which and close to the edge of the articulating surface, arises a strong and broad ligament, that is inserted into the os calcis. Under this lies another ligament, which, arising from the anterior tubercle, is also in- serted into the os calcis. It is to be observed, that the origin of the latter is anterior to that of the former, but its insertion pos- terior, so that these lateral ligaments cross each other in the form of an x. The external articulating protuberance of the _astragalus on which the tibia revolves, has, as has been already stated, a nearly circular outline, and the attachments of the ligaments just described, are at points on the outside of the os calcis, which would lie nearly in the circumference of that circle, were it continued from the articulating surface ; so that each of these ligaments has one of its extremities fixed in a cer- tain point of the circumference, while its opposite extremity revolves during the motion of the joint, nearly in the circum- ference of the same circle. This observation applies likewise to the two lateral ligaments on the inner side of the joint, which have nearly the same relation to each other, and to the general contour of the joint, as that just described; so it is obvious, that during the rotation of the joint, as the origins of these _ligaments move along the same circumference in which their attachments are fixed, the ligaments will be most stretched when they correspond to diameters of that circle. Now it is so arranged that this happens at the same time for all, and consequently the ligaments on each side correspond not merely as to direction, but as to the point of time they be- come most stretched, which is nearly at the moment that the joint has no tendency to move either way, and at that moment, it is to be observed, that although the ligaments are most tense, and of course react on their points of attachment with greatest force, yet this produces no motion, as the force is exerted in a direction perpendicular to the circumference; but as soon as the tibia is moved beyond this point of inaction for the liga- ments, the latter, no longer representing diameters, by their contractile force evidently tend to accelerate the motion, and ‘as they all act in the same direction, and are assisted by the NEW SERIES, VOL. Iv. No. I. JAN. 1831. D 50 Dr Graves on the Ankle-joint of the Horse, shape of the articulating surfaces, a sudden motion of flexion or extension is thus: produced. The preceding explanation supposes the ligaments of this joint to possess, contrary to the nature of ligaments in general, a certain degree of elasticity, which was evidently the case in all, bud particularly i in the most deep-seated of: those on the inner side of the j joint, which, therefore, appears most concern- ed in: producing the sudden motion, whether of flexion or ex- tension. In the autumn of 1829, two of: the species of whale called Delphinus diodon, by Hunter, Hyperoodon, by La-Cepede, and Ceto-diodon, by Dr Jacob, were captured near Dublin, oue of which, measuring about sixteen feet’ in length, I pro- cured for the purpose of preparing its skeleton. After the spinal column had undergone maceration for a few days, I found that the intervertebral’ substance could be easily detached from the bodies of the vertebrae, and that-it carried with it, firmly attached to each of its extremities, a flat circular bone, about a quarter of an inch in thickness, and exactly corresponding in the extent and shape of its surface, to the surface of the body of the vertebra, from which it had been separated. The separation was effected with facility, and took place spontaneously and completely when the maceration had been continued some time longer. The surface of the flat bone, where it had been adherent to the body of the vertebra, was of a spongy texture, afforded a passage to many blood-vessels, and was marked by numerous sharp projections and deep furrows, diverging from its centre, and answering to similar projections and furrows on the de- nuded extremity of the vertebra; of course the surface of these bones varied in shape and. size with the extremities of the vertebra to which they were attached, beimg from five to six inches in diameter at the dorsal, and not more than one inch at the last caudal vertebra. , The substance of these bones towards the intervertebral substance was of much harder and closer texture than that of the bodies of the vertebrae themselves, and where it was ad- herent to the intervertebral ‘substance, it had a smooth surface, marked with a great number of concentric lines, answering to and the Vertebree of the Whale. 51 the arrangement of the fibres in the intervertebral tissue, which adhered to this face of the bone with great strength. This marking was deficient towards the centre where the interverte- bral substance is fluid. ‘The facility with which these bones are detached, is the reason why we never find them adhering to the vertebre of those young whales which have been wrecked on our coast, and whose skeletons have been exposed to the action of the waves and the weather. Their flat shape too renders them liable to be covered by the sand, and hence I have never known them to be found separately, even when the vertebra and other bones of this species of whale were scattered along the coast in great numbers, as happened at Dungarvan some years after several of these animals had been i SS and dragged ashore by the fishermen. The bones I have described must evidently ibe considered in the light of terminal epiphyses of the bodies of the verte- bre, and are deserving of notice on account of the facility with which they can be detached, even in very large, and of course not very young animals of this species, as I observed in the two skeletons preserved in the College of Surgeons, one of which measures thirty feet in length ; so that when the skele- ton has been artificially prepared, they resemble separate inter- vertebral bones rather than vertebral epiphyses. In the land mammalia the consolidation takes place much more rapidly, and a few years are sufficient to efface all traces of former separa- tion between the epiphyses and the body of the vertebra ; the comparative slowness of this process in the whale, is probably referable to the longevity of the animal, and the greater length of time necessary to complete its growth. A knowledge of this fact puts us in possession of a new and useful mark of the animals age, independent of its size, and it is for this purpose I have brought it forward, for although not noticed by any author I have seen on the Anatomy of Whales, it must never- theless have been known to several. If we find that the ter. minal epiphysis has become completely united to the body cf the vertebra, we may be assured that the bone, whether large or smal], belonged to an animal arrived at maturity ; but if not, we may conclude that it had not yet attained to its great- 52 Dr Graves on the Ankle-Joint of the Horse, &c. est size. To facilitate this inquiry, I may remark, that a very slight examination of a vertebra is sufficient to determine, whether the epiphysis has, or has not been. detached ; as in the former case the surface is marked by deep ridges and fur- rows diverging from the centre towards the circumference ; whereas in the latter, if the animal was of moderate size, the marking consists of concentric lines, answering to the attach- ments of the intervertebral substance ; and if the individual was very large, these concentric lines are exaggerated into concen- ‘tric furrows ; and whether the attachments of the intervertebral substance be marked by concentric lines or by concentric fur- rows, a considerable portion of the central part of the bone, where it had been in contact with the internal substance of the intervertebral ligaments, is quite destitute of this marking, and presents a striking contrast to the rest of the surface. I am not aware that the true cause of this remarkable dif- ference between the markings on the extremities of the verte- bree of the cetacea has been before explained. ‘It may not be uninteresting to add, that the cranium of the Delphinus diodon in my possession, and both those in the Museum of the College of Surgeons, present, in a very re- markable manner, the want of symmetry between the right and the left sides of the cranium, which was first observed "f Meckel in the skulls of the Cetacea. Note. Since the preceding notice concerning the hock-joint of the horse was submitted to the Academy, I have had an opportu- nity of examining two horses affected with string-halt, and am inclined to attribute the disease to a spasmodic affection of the flexors of the limb generally, rather than to any derangement in the structure of the hock-joint. It may be right to mention that the following authors on Comparative Anatomy, and the Anatomy of the Horse, have been searched, but they contain no notice of the peculiarity i in the structure of the hock-joint, above described. —Macartney, Cuvier, Carus, Blumenbach, “Meckel, Clater, Blaine, Stubbs, Percivall, Boardman, White, Lawrence, Osmer, Home, Bourgelat. _Mr Potter on the Reflective Powers of Glass. 53 Art. V.—An Account of Experiments to determine the re- flective powers of Crown, Plate, and Flint-Glass, at diffe- rent angles of incidence ; and an investigation towards deter- . mining the Law by which the reflective power varies in trans- parent bodies possessing the property of single refraction. By R. Porter, Esq. Junior. Communicated by the Author As soon as I had sent my former paper on the reflective powers of metals to the President of the Royal Society, when considering the cause of reflection I naturally asked my- self the question, “* If this cause, as Sir Isaac Newton, and philosophers generally after him, have supposed, is the same principle existing at the surfaces of all bodies; then, if metals reflect less light when incident more obliquely, how is it that with the same principle transparent bodies should reflect more ?” ; We have no other alternative than to allow that there must be other forces concerned besides the one which is the imme- diate cause of reflexion. In our inquiries into the connection existing between the different physical properties of matter, our only safe and legitimate course is by induction from expe- riments.. It isa much less laborious one to speculate in the closet on the isolated facts we have observed, and to frame theories to account for them, but every page of the history of science warns us against placing too much reliance on abstract reasoning. We there see that the speculations of the greatest minds have been oftener found wrong than right when they have ventured into depths beyond the fair induction from phe- nomena observed ; and hence the motive which induced me to undertake the patience-trying investigation of the reflecting and transmitting powers of crown, plate, and flint-glass at diffe- rent angles of incidence, which is contained in the few follow- ing pages. Their possessing the same properties of density, refractive power, and capacity for heat in different degrees, gave me reason to hope, that, if the forces which cause the phe- nomena of reflection depended on any of these, it would be manifest in the different results. The proof advanced by Sir Isaac Newton, that the reflection 54 Mr Potter on the Reflective Powers at the surfaces of bodies cannot be caused by the particles of light striking the solid particles, (say solid ponderable particles, ) must, I think, be allowed by every one to be sufficient ; but if other proof were necessary, it might be derived from the fact, which is familiar to every working optician, that both glass and metal polish equally well in every possible direction, and no figure bounded by planes, (which is essential,) can be as- signed to the ultimate particles of matter, which will present the same face in every direction. The theories which have been built on the supposition of light and heat being a mere condition of matter, as consisting in undulations or vibrations, are quite insufficient to account for the phenomena of reflec- tion. The laws incontrovertibly point out that the effect is governed by the physical properties of bodies, and this takes the cause entirely away from all purely mechanical rules, and metaphysico-mathematical calculations. When we can account for double decomposition and elective chemical affinity by me- chanical hypotheses alone, we may then with propriety apply them in optical physics, but not until then. ‘The whole phe- nomena of light and caloric exhibit them possessed of proper- ties analogous in affinities and repulsions to what we observe in ponderable matter, and the distance between the subtile ga- seous matters, such as hydrogen and nitrogen, and the heavy inoxidizable metals, seems scarcely less than the distance be- tween them, and those subtile matters which acknowledge no subjection to the influence of gravity. The phenomena of the reflection of light not allowing us to compare it with the echo of sound, by its impinging against the hard ponderable particles of bodies, philosophers have of necessity considered it as the effect of some subtile power at the surfaces of bodies. The great advancement of chemical ' science gives us an advantage in our inquiries which the opti- cians of a century ago were almost entirely without, and which we must not overlook. The discovery of Dr Black of the at- traction between caloric and ponderable matter, combined with other discoveries, has induced some philosophers to consider light and caloric as the same matter in different circumstances, and reflection as caused by an atmosphere of caloric retained around bodies by this attraction. ‘This is the most probable of Crown, Plate, and Flint-Glass. 55 theory that we can adopt on attentively considering the facts within our knowledge; ‘but it has not yet received that proof which would be desirable. . My. experiments, with both metals and glass, tend to support it; and if it should be found to hold in one other metal I should consider it as established. _. The word atmosphere is perhaps as correct as any we have to give an idea of an elastic medium held in its place by the attraction between it and the mass it surrounds, and the experiments on the flexion of light show us that it extends to a distance from the surface, and that its density is some func- tion of the affinity and distance. This consideration of an at- mosphere enables us to account for the angle of incidence being always equal to. the angle of reflection, by the path of a ray thrown into such an atmosphere which resists its entrance by a repulsive principle, being similar to the path of a projectile acted upon in a converse manner by the force of gravity ; and the depth to which any ray would penetrate by its own endeavour alone, must depend on its projectile force compared with the repulsive force of the atmosphere. This repulsive power appears to be sufficient to reflect back every ray, even if incident perpendicularly with the velocity that we find it possessed of if there were no attraction between the rays of light and the ponderable matter. On these attractions, com- bined with the projectile force of the rays, depend the laws which govern the effect we find by experiment. In the simple undecompounded bodies of the metals the reflective power is the greatest; but my experiments show that the attractive force in them increases with the angle of incidence comparatively with the reflective force, and the law of the effect shows that they both vary as the sine of incidence. When we come to examine the two in transparent substances, we shall find proof of the same attractive and repulsive force in them, with ano- ther attractive force in addition, which varies according to a different law. The mode of action of this latter force enables us to identify it with the refractive power, and it exhibits itself closely connected with the clectro-chemical constitution of transparent bodies. In the consideration of an atmosphere or a fluid, which is indispensable in every theory of light, it can- not be defined as a congregation of hard homogeneous particles 56 Mr Potter on the Reflective Powers in contact with each other. We should never call a heap of sand a fluid. The idea implies a constitution which allows the particles free motion amongst each other at the same time that they are subject to an attraction which keeps them together. If, then, the particles of light and caloric do act upon each other in this manner, as they certainly do, we are driven to the necessity of an intermediate agent, as in all ponderable fluids within our cognizance, possessed of satellite properties, and attending on the base of light or caloric, as caloric attends on ponderable matter, and gives to it the solid, liquid, or ga- seous form, according to its presence in intensity, and the affi- nity between them. I believe that all our researches will con- firm this view, and that, so far from its being a fanciful hypo- thesis, we cannot be led to any other conclusion when we consider with a careful and earnest attention the phenomena of light. This constitution of a base, combined with satellite matter, if I may so call it, shows us the cause and mode of ac- tion of the elastic or repulsive properties, and gives us a clew to the solution of those singular and highly i este, ane fications which light is capable of. The measurements of the light reflected and trasstlehi by glass, in the experiments of which the results are about to be "given; were taken with the same photometer as the former ones with metal, but with such alterations as the great diffe- rence in the reflective power of glass at different incidences rendered necessary ; and I used a small instrument furnished | with a plumb-line, which could be placed on, and was move- able round the same point which carried the arm with the re- flector, to insure correctly the incidence, and the position of the reflecting substance under examination. When I first commenced the experiments, they appeared fo give more light, as reflected, when incident nearly perpendicu- larly than when rather more obliquely ; I readily saw that this arose from the extraneous light reflected by the different parts of the apparatus situated near the lamp ; and when the lamp and reflector had to be brought very near the screen, it bore a very considerable ratio to the whole light reflected. Whilst this extraneous light remained undetermined, I was convinced that the measurements would be comparatively worthless, and of Crown, Plate and Flint-Glass. 57 for some time I despaired of finding any method of determin- ing it; but, however, at last I hit upon the following plan. I found that glass ground rough with coarse sand on one side, in transmitting the light incident on it, disperses it pretty evenly without losing too much of it for the purpose, and con- sidered, that, if a certain area of this ground surface was placed. together with the left hand lamp, so as to give an equal illu. mination with the gross’ light reflected, then the area re- quired to give an equal one with the extraneous light, being compared with the whole area, would give the ratio between the gross and extraneous light, the apparatus being in the same position as in the measurements, but with the light from the reflector turned off or on the thin paper, as required. This method is quite efficacious, and the extraneous light in the tables may generally be considered as determined to less than a tenth or twelfth part. The quantities up to 70° were measured, but at 80°, and 85° being so small in proportion to the whole, they are only estimated. The pieces of window-glass were selected very carefully from amongst large quantities, and of all I examined, I only found one piece of 45 inches in length, and 1,% in breadth, which was flat on both sides, and of good clear surface. In the larger portion of window-glass there is a slight mistyness to be seen, when it is wiped very clean, which is on the surface: of the glass, and which, when examined with a lens, appears to have arisen in the manufacture, the surface being torn in small spots, by its becoming solid before the interior. The pieces of plate and flint-glass were ground flat and po- lished for the purpose. The reflection at the second surface was prevented, when required to be so, by a coating of black varnish; that used for the crown and plate-glass was black sealing-wax dissolved in alcohol; and that for the flint was a similar solution of balsam of Tolu, with some fine soot from the flame of a candle mixed in it. I have not yet examined the refractive powers of the glass used; but in the plate-glass it will be rather higher than in the crown, because, when var- nished as above, a faint blue reflection was perceptible at the second surface, which was not the case with the crown glass. The flint-glass also exhibited a similar one with its varnish. 58 Mr Potter on the Reflective Powers Measurements of the Light :reflected at the first surface of crown glass, specific gravity 2.541, three pieces used of 13 by Le Hié> by 1} and 43, by 1,% inches, mn thickness about ’, inch. Gross re- To ‘be deducted = cto tet ecomemn 10 4.59 a ths,=.93 3.66 20% ABA) FO ou 72 8.Be 30° 4.69. a, S2 AT 40° 494 Sa 50? B68. ug) iB, BB 60 Re ao ae 70° 1395 2 95 18:70 80° 3400 =, 27 88.76 85° 5449 QL 5428 85° 55.08 =, 22 5486 Measurements of the light reflected at both surfaces of crown glass, three pieces used of lyg by 14, 13 by 1g, and 43 by 13 inches. 10 «7.67 ths 1.07 6.60 ao 6=— vgs 80h 6.84 500 30° Bap ee. 10S. Coe g0° 852 1087.49 10% TGF, vil OF 689 20° 7,86 = 108_~«s«6.83 of Crown, Plate, and Flint-Glass. Par” ese F 21.01" §° 188 40° 984 1.00... 8.34 50° 1087 86 9.71 6° 198 = 88 1297 10° 23.58 inp AY. 23.11 me S27 ge ae’ -"SRan $o° 42.50 «5, 85 42.15 59 The above measurements with crown glass of the reflection at the surfaces are, I think, as correct as I could expect to determine them ; but those of the transmitted light which fol- low, show a liability to error to the amount of about #5 of the whole, and yet I have little hope of getting a better set, with- out great practice, on account of the colour which the glass gives to the light. The eye often becomes prejudiced when judging between a green and an orange. Measurements of the light transmitted by crown glass to de- termine the quantity lost in the glass and dispersed. Total trans- Incidence- mitted of 0° 70° Average. every 100. 86.16 aos 86.83 86.30 87.49 (S38). er 86.03 \eio1 85.02 81.64 4 <4. 81.52 70.79 70.79 13.17 12.90 14.98 18.48 29.21 Reflected Reflected at and lost- surfaces. 6.60 7.40 9.71 23.00 Loss. 6.30 7.58 8.77 6.21 60 Mr Potter on the Reflective Powers Measurements of the Light reflected at the first surface of plate glass, spec. gravity 2.511, one piece used 2 inches by 15 and thickness 3} inch. Biea ce To be deducted ar eon every 100. as extraneous. heads 10° 94.54 aoths, =.88 3.71 i”: ‘440 & 14 3.66 Incidence. 500 20° 9482 FF -58 RTE 30 456 = AT = 4.09 40° 478 884.40 BOF i Segue Be okeirls gy oth eae GOP, 1 HBB chi gap verre She sil *60 833° 2 88’ 8.00 70° 1484 32 28 14.06 80° $4.29 = 27 8402 80° 84.84 87 84.57 85° 5480 =, 21 54.59 Measurements of the light reflected at both surfaces of plate glass. 10° 7.72 ths, =.97 6.75 i” 87.76 5 OT 679 a0. Hig S058 90; |, 101 se° BIG ee fo 16 7.40 “e~ B98 SO 69 8 .8a7 50 1048 = 67 = 9.8 * This was a careful re-measurement, when I found reason to suspect some error in the other- . 3 of Crown, Plate, and Flint-Glass. 61 50° 1045 6.9 Go 1497 * 68 13.59 70° 2502 2% 10 24.32 7° 2489 5, 69 24.20 Measurements of the light transmitted by plate. glass, to de- termine the quantity lost in the glass and dispersed. Total trans- pidiliets piitted of Reflected Reflected at every 100. and lost. surfaces. 1-08 0° 91.42 8.58 10° 90.84 9.16 6.77 2.39 go° 7.01 30° 90.64 9.36 7.40 1.96 40° 89.36 10.64 8.27 2.37 50° 87.51 12.49 9.80 2.69 60° 83.94 16.06 1859 247 70° 14.64 25.36 24.26 1.10 ' 80° 54.83 45.17 Measurements of the Light reflected at the first surface of flint-glass, spec. gravity 3.225, one piece used by 1{ by 1,1, inches, and thickness }, inch. Gross re- e Reflected Incidence. flected of 1° be deducted my every 100. of Facencone, donee 10° 5.08 = “ths,=1.26 3.82 20° 494 81. 413 30° 5.05 2 60 4.45 40° 529 S 45 484 50° 6.73 = 43 ~—«6.30 60° 9.87. = 48 8.89 7 1144 33 17.06 8085.96 * 28 35.68 Se 22 BT27 - & Mr Potter on the Reflective Powers Measurements of the Light reflected at both surfaces of flint glass. Inidece, fect oi Ty Medea’ bythe 10° 8.56 io ce 49 «= AROT 10° $56. = 49 SOT 20° seit: geo geeee 20° B81. ge 65 iT B.16 ap" §a7 "= «° eren ie 40° W090 (22 30. on 083 50° 1246 35 59 11.87 60° 16.48 20! . .52.1)'15.96 70. 2071 1c) =| A Re Measurements of the Light transmitted by flint-glass, to de- termine the quantity lost in the glass and dispersed. Total trans- Incidence. mitted of Beige Detected ' é' every 100. °” ost at surfaces. “L°8* 0° 87.85 12.15 . 10° 86.97 13.03 8.07 4.96 30° 86.25 13.75 9.12 4.63 50° 83.42 16.58 11.87 4.71 50° 83.99 16.01 11.87 |... 4:14 70° 71.05 28.95 27.22 1.73 80° 52.97 47.03 When I first undertook the investigation of the law by which the reflective power varies in glass, the most promising manner in which I could construct geometrically the experi- ments, seemed to be that of considering the various rays of light as falling upon one point in a reflecting plane at different incidences; and this idea has eventually enabled me to discover the law of the variation of the reflective power at different in- of Crown, Plate, and Flint-Glass. 63 cidences both for glass and metal. When I tried in this man- ner the quantities of light reflected by window-glass at the first surface, from a rough preliminary course of experiments, and before I had tried the measurements previously taken with metal, the quantities being set off on the perpendiculars they took a curved form, which seemed to resemble ‘an hyperbola, and I was struck with the similarity between it and those given by Sir Isaac Newton, as produced by inflection. On a closer inspection, however, the curve appears not sy- metrical, and so not correctly an hyperbola, or any line of the second order; but we shall find that this appearance arises only from the vertex of the curve not being on the chord of the quadrantal arc; and when we have found the position of its assymptotes, it proves to be a true hyperbola of the second order of lines; and from its properties we may calculate the light reflected at every incidence, when we know the values of certain constants which enter into the equation, and which have different values for different sorts of glass. On applying the formula to Bouguer’s experiments on the reflection by water, I find-a very near agreement there also, so that I have no doubt that this formula is true for the first surface of all transparent bodies, both liquid and solid, which have only the property of single refraction. The geometrical construction being made in a similar manner to the one detailed in my former paper on the reflective power of metals, we obtain a figure similar to Plate I. Fig. 4. and, taking the point O for the origin of the co-ordinates, we have y = the quantity of light reflected, w = the sine of incidence, 7 = ra- dius, and the quantity of light supposed to be cient, and the equation of the reflective power is y = a + oe —— where a, 6, and ¢, are indeterminate constants, having different values for different singly refracting transparent bodies, depending on the peculiar property of each. This equation is derived from that of the rectangular hy- perbola between the assymptotes a” y/ = c*, where 7/ = y—a and a =r+b—w#, a= the distance of this assymptote ¢ 7, from the radius O Q, and d the distance of the other assymptote from a perpendicular drawn to the extremity of that radius. 64 Mr Potter on the — Powers Taking the formula y = a+ ———>— and r= 100, I find the values of the constants, as near as al can determine them from the measurements, to be about as follows, viz. for crown glass, spec. gravity 2.541, a = 2.7, b= 1.04, ¢ = 76; for plate glass, spec. eretty 2.511, and refractive power rather higher than crown, a = 2.58, b = 1.13, c = 9; and for flint glass, spec. gravity 3.225, a = - 2.63, 6b = 1.44, c — 10. ‘On these data we have the quantities of light reflected as in the following table; and we find them to agree as near with the experiments as can be expected ; and few experimenters will be able to obtain the measurements nearer, generally, to the calculations, until they have had very great practice in pho- tometry. Table of the quantities of light reflected by glass at the first surface, calculated from the formula y = a + hres z Incidence. Crown. Plate. Flint. 2.541 2.511 9.225 0° 3.452 3.380 3.615 10° 3.608 3.546 3.819 20° 3.837 3.790 4.117 30° 4.189 4.164 4.574 40° 4.767 4.778 5.320 50° 5.810 5.882 6.656 ti 60° 7.964 8.155 9.369 . 70° 13.448 13.891 16.015 ‘ 80° 32.396 33.155 36.422 85° 56.202 56.204 57.559 90° 75.776 74.261 72.074 Before we can investigate the law for the second surface, it will be necessary to find the amount of the first reflection at that surface proportionally to the quantity incident on it; but, as will be seen by Fig. 5, Plate I. that the quantity of the reflection at both surfaces, as determined by the measurements, - is the sum of the reflection at the first surface er, and of the reflections é 7’, e” 7", er”, &c. from the second surface. Now, of Crown, Plate, and Flint-Glass. 65 if there were no light lost in the glass, we might determine the first rei at the second surface iy simply finding the value of — in the series [4 [wt fn 1) &e., which will be readily seen by the figure to represent a reflections ¢ 7’, e” r", e” r", &c. when we put = for the proportion of light first re- flected at g. Of this series we know the sum, it being the differ- ence between the whole reflection and that for the first surface. $ 1—s ‘ zs . 1 Putting s = this sum, we have —= This value of ~ requires still to be corrected for the quan- tity lost in the glass and dispersed ; but if we divide the whole loss proportionally between the light which should be trans- mitted and reflected at @ from the series, we may make use of this proportion without any sensible error, as the difference be- tween it and the true quantity is trifling i in comparison to the limit which must be allowed for error in the measurements. When we know the law of the variation in the loss and re- flection, it would be better to use the calculated quantities, in applying them to another course of experiments than the ex- perimental ones, as we then avoid the liability to twofold errors. The formula for the first surface we have already, and I now proceed to discuss that for the absorption or loss. ‘The for- mula for finding the loss of light sustained in passing through any thickness of a transparent medium is this; if a part p of the whole light passes through a thickness a, then for any other thickness n a, the proportion passing through will be p”. Now, if upon a review of the measurements, we can agree upon the quantity as lost at a perpendicular incidence, we know the proportion passing through the known thickness, and for every other incidence, the proportion passing through, would be p”, where m is the tabular secant of the angle of refraction. If we take 6.4 as lost in every 100 in the crown glass of the experi- ments, 2.3 as lost inthe plate, and 4.9 as lost, in the flint, when incident perpendicularly, we have the calculated loss on. the light, which traverses the thickness of the glass, as per the fol- lowing table: NEW SERIES, VOL. Iv. No. I. JAN. 1831. E 66 Mr Potter on the Reflective Powers Calculation of the Light which would be lost in glass at dif- ferent incidences from the differences in thickness. Incidence. Crown. Plate. Flint. 10° 6.45 2.32 4.96 20 6.57 2.37 5.05 30 6.77 2.45 5.20 40 7.01 2.55 5.87 50 Wed 2.66 5.56 60 7.56 2.79 5.75 70 7.78 2.84 5.92 On a first view of this table we see that we cannot avail our- selves of it. Though there is no doubt of the correctness of the formula for different thicknesses when the incidence is per- pendicular to the first surface, it appears that we cannot com- pare different incidences together ; and it shows, that the modi- fication impressed upon light even affects its disposition to be absorbed in singly refracting substances, which I believe has never been before discovered. 'Though the liability to double error, arising from comparing two sets of measurements, pre- vents us ascertaining the law of the variation, yet the small loss at the highest incidence in every set leaves no doubt of the fact and its cause. This cause affects also the reflection at the second surface ; and, therefore, any law for the second sur- face of plates must have this effect considered as an essential part. 'The only correct method is to measure the light reflected with prisms, where the light at each incidence enters and emerges perpendicularly to the surface ; but this will require time and labour which I shall not be able to devote to it. In the following table I have calculated os my preci at the second surface from the series - — ats 3 = 2. =s? &e. adding the proportion of loss from the measurements. ae see that from it we have no reason to reject the law, that the re- flective power at the second surface is equal to that at the first, when the incident and refracted rays have the same angular deviations. of Crown, Plate, and Flint-Glass. 67 Table for the first reflection at the second surface of glass plates, calculated from the measurements at both surfaces. Crown. re | Flint. rll 3 ; a. alps ) eh ee a}2 |88 8 laa | |e2/5 [2a |e |s2 || 2 105757] 8.20.22) 3.42\,-'5| 9.46).08| 3.54\57 ag] 4621.25] 4.87 20 |arns| 2:22 sray| 3-46 sa7| 44) 80 || 3.40198] 3.68lpsc| 3-49)-07] 3.56:557| 5-00.25) 5.25 40 || 3.901 | — lero] 3.81).09| 3.90;gag} 5-47 50 |gy5| 4311-44) 4.75), | 4.94/19] 4.46] 55 5.92.29) 6.21 60 |izaz| 5.75 ig] 6.29).17} 6.46lizcg} 7-85 70 | ts h12.1519913.07 21 |18.69],17|18.86] gz |15.40|31}15.71 80 | 555 [16:89 The irregularity in these measurements for both surfaces is more than I expected to have found it, and T intend trying a few of them again; and hope, in the next. Number of this Journal, to be able to give them, with also.a further analysis of the law for the first surface, and an examination of the con- nection between the values of the constants in the formula, and the physical properties of solid transparent bodies. It will have been observed, that, as im metal, so in glass, only a portion of the light is reflected, even when the incidence is the greatest possible ; and the quantity r— # being the co- versed sine of incidence, may be examined as a function of the sine and cosine, or of the parallel and perpendicular motion of the rays of light to the surface. I must here beg to correct an omission in my former paper on the reflective power of metals. When speaking of the ge- neral opinion being, that all substances reflected light most copiously when incident most obliquely, I ought to have men- tioned the exception as to bodies of rough surface, which has been known since Bouguer’s experiments with silver, Paris plaster, and paper 68 Dr Hartmann’s Mineralogical, Chemical, ART. VI.— Mineralogical, Geological, and Chemical No- tices. Communicated by Dr Cuartes Hartmann, of Blankenburg, on the Harz, M. W.S. &e. _-. 1. Ow the Natural not Ouyded combinations of Iettibes and Arsenic, Extract from a paper of Professor Henry Rose of Berlin, in the xv. vol. of Poggendorff’s Annalen ie Physic “und Chemie.—According to Professor H. Rose the following minerals belong to this class of substances. a. Zinkenite from the Wolfsberg in the eastern Harz. 'The analysis of this ore is already communicated in No. xii. of this Journal, and the external descr iption from Professor Gustavus Rose, in No. xi. - The composition is the following : Sulphur, 22.58 Antimony, 44.39 Lead, 31.84 Copper, 0.42 os 99.23 Chemical formula Fb + Pb. * b. Miargyrite (from égyugoc, silver, and yi», less, because it contains less silver than the red silver,) or the hemiprismatic. rubyblende of Mohs, (Haidinger, T'reatise, vol. iii. P a) ' from Briunsdorff in Saxony. It contains: Sulphur, 21.95 Antimony, 39.14 . hla Silver .. 86.40 wa _ Copper, 1.06 Iron; 0.62 99.17 Chemical formula Fb ee Ag. C Jamesonite from Cornwall. ‘The analysis of this ore is — already communicated in No. xii. of this Journal. Tt con- tains: ; Sulphur, 22.15 Antimony, 34.40 Lead, 40.75 Copper, 0.13 Iron, « T 280 99.72. Chemic. Form. 2 Fb +3 Pb. * The ' on the letters of the formule signifies an atom of silver ; in like manner . signifies an atom of oxygen. dove and Geological Notices. 69 _d. Plumose Grey Antimony (Federerz) from Wolfsberg in the eastern Harz, in capillary crystals, consists of : Sulphur, 19.72 a - Antimony, 31.04 ~~ ° Lead, 46.87 Tron 130 Zinc, = 0.08 99.01 _ Chemical Formula ¥b + 2.P%. -e. Red Silver, a light variety from Joachimsthal in Bohe- mia, with the specific gravity = 5.552. Composition: ~ Sulphur, 19.51 Antimony, 0.69 Arsenic, 15.09 Silver, . 64.67 99.96 Arsenic and Antimony are isomorphous in the red silver. _ f. Brittle Silver Glance from Schemnitz in Hungary, cry- stallized in six-sided prisms and with a specific gravity = 6. xh Composition : Sulphur, 16.42 ‘Antimony, 14.68 Silver, 68.54 Copper, 0.64 100.28 Chemical Formula Fb +6 Ag. . Bournonite from the Pfaffenberg Mine in the eastern Hi: with the following composition : Sulphur, 20.31 Antimony, 26,28 Lead, 40.84 Copper, 12.65 / “a ue 100.08 Chemic. Form. Cu? Fb + 2 Pps ro. h. Polybasite ( from 70Avs, much, and Pécs, basis, because it 70 Dr Hartmann’s Mineralogical, Chemical, contains the greatest quantity of the basis,) a new species, This mineral was confounded with the brittle silver glance. The external description is given by Professor G. Rose, . Crystals: Regular six-sided prisms, ordinary, jlow, and tabu- lar, terminated by planes, which are perpendicular to the axis. The surface of the lateral planes is streaked across, the sur- face of the terminal planes parallel to the planes of a equilate- ral triangle, or parallel to the alternate terminal edges of the six-sided prism. In consequence of this the crystals must be rhombohedral. Cleavage is not observable; fracture uneven ; colour iron black ; lustre metallic ; streak unchanged ; sectile. ; Hardness = 2.0,..2.5. spec. gr. of the variety from Guarisa- mey in Mexico = 6.214. Chemical composition : Sulphur, 17.04 Antimony, 5.09 Arsenic, 3.74 Silver, 64.29 Copper, 9.93 Iron, ; 0.06 Chem. Form. Cu Fy P Ag? Fb 100.15 ‘As aa The polybasite is found crystallized, massive, and dissemi- nated in silver veins, in Guanaxuato and Guarisamey, in Mexico, and in the Mine Morgenstern at Freiberg in Saxony, i. Grey Copper or Fahlerz. Composition : Sul- Anti- Arse- ; » Zine. Silv phur. mony. nic. tron ° ooh Varieties. 1. From St Marie aux Mines in Alsace, 26.83 12.46 10.19 4.66 3.69 0.60 40,60 2. Gersdorf near Freiberg, 26.33 16.52 7.21 4.89 2.76 2387 38.63 3. Kapnik in ey Hungary, 25.77 23.94 2.88 0.86 7.29 0.62 37.98 4. Dillenburg in | Nassau, 25.03 25.27 2.26 1.52 6.85 0.83 38.42 Cop- r. and Geological Notices. 7A 5. Mine Zidda at sali » Clausthal, 24.73 28.24 —— 2.27 5.55 4.97 34.48 6. Mine Wenzel _ near Wolfach, Didi Baden, 23.52 26.63 3.72 3.10 —— 17.71 25.23 7. Mine Kabacht, _ nearFreiberg, 21:17 24.63 ~ When sulphuret of antimony and sulphuret of arsenic is 598 0.99 31.29 14.81 signed with R, sulphuret of iron and sulphuret of zinc with R, and sulphuret of copper with R, the composition of the varieties 1—4, which contains only a small quantity of silver, may be expressed by =, ,, sis . R'R+2 R‘ R. The composition of the varieties which contains silver is more difficult to explain. k. Nickeliferous Grey Antimony. 'Yhis consists of : Sulphur, 15.98 Antimony, 55.76 Nickel, 27.36 ens 99.10 Formula Ni S? + Ni Sd. . 2. The Atomic. Weight of the Lithium, Mr R. Hermann of Moscau has found, oxygen = 100, — 152.1.—Poggendorff’s Annalen, vol. xv. p. 483. 3. The same chemist has detected under the radiated tale from the Ural a new species called Pyrophyllite. Before the blowpipe it exfoliates flabelliform to a great mass. The che- mical composition is the following Silica)’ SL 59.99 Alumina, “ 29.46 Magnesia, - 4.00 Oxide of iron, - 1.80 Water, - 5.62 100.67 This “Bese to the formula M® Si? + 3 AP Si® 4 10 H. Poggendorff, vol. xv. p. 592. 72 Dr Hartmann’s Mineralogical, Chemical, 4. In a potter’s furnace at Oranienburg near Berlin, Pro-' fessor Mitscherlich has found artificial crystals of oxide of iron which corresponds to tabular forms from the ‘rhombohedron) and the terminal face perpendicular to the axis. een vol. xv. p. 630. 5. The atomic weight of Titanium is found by Professor H. Rose of Berlin, -Oxygen — 100, = 303.686 ; and according to Nenana = 353.554. erat gendorff, vol. xv. p. 145. 6. Professor Gustavus Rose of Berlin has found thatthe glassy feldspar from Laachek on the Rhine, and from Vesu- vius, forms a distinct species. ‘The observed crystals have nearly all the faces of the Adularia, and the same parallelism of edges. ‘Twin-crystals like them, Fig. 80 and 81 from Moh’s T'reatise on Mineralogy, vol. ii. indicate that the edge between o and M and the face P, have not the same inclination to the axis. Professor Rose gives the following measurements of the angles : T on T'— 119° 21’. zonP= 129° 86. Pon T' = 112°19. x2 ono = 153°20. Tony = 134° 34. M on n = 134° 43’. PonM= 89°59’, 5. P on 0 — 124° 41’. . The vertical axis is inclined to the fore horizontal under an angle of 88°, 56’. The specific gravity is found by. Professor liens on. the variety from Vesuvius, - - = 2.553. On a variety from the Eissel, > - = 2.519. By Professor Breithaupt of Freiberg, =. = 2.582. According to the opticalresearches of Professor Mitscherlich it is in this respect different from the Adularia. The chemical composition of the glassy feldspar is also dif- ferent from that of the Adularia; and Professor Rose will prove this by an analysis after his return from a journey to the Ural Mountains, where he and Professor Ehrenberg of Berlin, (the Egyptian traveller,) accompany his excellen- cy, the privy counsellor, Alexander de Humboldt. These notices on the glassy feldspath, which he called Ryake- lithe, (from ia%, lava, and. 0s, stone,) are only a part of and Geological Notices. 73 a treatise on the minerals of the feldspath family.—Poggen- dorff, vol. xv- p. 193. 7. Analysis of the -titaniferous owidulated iron, or iron sand from Egersund in Norway, by Professor H. Rose. Oxyde of iron, 42.70 Protoxide of iron, 1357 Titanic acid, 43.73 LOMO Bi gendart vol. xv. p. 276. 8. Analysis of the Scheererite or Naphtaline résineuse pris- matique, from Uznach, pear St Gidea in Switzerland, by Macaire-Prinsep : Carbon, 73.0 or 1 atom. Hydrogen, 24.0 or 2 atoms. Poggendorff, vol. xv. p. 298. 9. Okenite, a new mineral species, detected by Professor Kobell of Munich, among the zeolitic minerals from Green- land, and named in honour of the celebrated naturalist, Pro- fessor Oken of Munich. ~ The mineral is found at Kudlisat in Disco Island, and forms an amygdaloid of a fibrous or thin radiated structure. Colour white, yellowish and bluish-white ; translucent ; lustre pearly. Hardness between that of feldspar and fluor ; spec. gravity = 2.28. - Before the blowpipe it melts with intumescence into a white enamel. Composition :— Silica, 55.64 © Lime, 26.59 Water with a lit- ~ the ammonia, 17.00 Alumina with a lit- tle oxide of iron, 0.53 99.76 Formula CS! + 2 Ag. Kastner’s Archiv. vol. xiv. p: 333. 74 Dr Hartmann’s Mineralogical Notices. 10. Analysis of the Nickel-Glance, from the mine Albertine, near Harzgerode, on the Harz, (See No. xviii. of this Journal,, P. ged by Mr sorted of Berenburg. ~ Arsenic, 35.635 “Sulphur, 22.581 - Nickel, 23.613 Cobalt, 00.444 ~ Iron, 9.282 Silica, 0.750 Moisture, 7.500 99.805 This result corresponds to the formula ; ot NG \ Se 4 3 Ni AS? 11. Seleniuret of Silver is now found in greater massive specimens at Tilkerode in the Harz, and not merely in thin veins in the seleniuret of lead. 12. Pure Selenium is obtained in the lead and silver works near Harzgerode, in the eastern Harz, according to the me- thod of Professor Mitscherlich, from the seleniuret of lead in very great masses, and sells in the mining-factory at Harz- gerode, for four Louis d’ors the ounce. 13. The system of crystallization of the Zinkenite from Wolfsberg in the eastern Harz, is prismatic and not rhombo- hedral, as I am convinced from an examination of fine speci- mens of this mineral found this summer. Mr Haidinger, “ Library of Useful Knowledge,” makes the crystals rhom- bohedral. 14. In the neighbourship of the old castle of Reinstein near Blankenburg, which stands on the top of a picturesque series of rocks which belongs to the green-sand, or Guadersandstein formation, in a sandland, there have been found this summer very fine and long vitreous tubes, (Blitarohren in Germany.) From a trunk in the upper part, two branches go off, some of 4 Sir Isaac Newton on Ocular Spectra, &c. 75 which are ten feet long, and from these proceed three little ee - Geological Map of the north-western part of Germany, in twenty-four leaves, projected by Professor Frederic Hoff- mann, (now in Berlin.) Berlin, by Simon Schropp and Com- pany.—This beautiful map, which contains the countries be- tween the Elbe and the Rhine, and from the Thuringia moun- tains to the great plain north of Hanover, with all details in the limiting of the rocks, is without doubt the best that exists, and better than the great maps of England by Greenough and Smith. A general geological map of the above countries, ac- companied by sections and a “ geological description” of that part of Germany in three volumes, also by Professor Hoffmann, will appear soon, and the whole will form one of the most im- portant geological works. It may be recommended to the British geologist on account of the formations of Germany being similar to those in England. 16. Privy Counsellor Dr Karsten of Berlin has begun a new series of his very valuable Archiv. fiir Bergbau und Hiitten- wesen,” (the first is finished with the 20th vol.) under the title, * Archiv. fiir Mineralogie, Geognosie, Berghau wu Hiitten- kunde,” or * Archives of Mineralogy, Geology, Mining and Metallurgy.” The first number contains, besides many other valuable papers, a geological description of the Scottish islands of Skye and Ege, by the Barons of Dechen and of Oeynhausen. 17. An’enlarged and improved German translation of the third edition of Bakewell’s Introduction to Geology, has just appeared, by the author of these notices. Arr. VIIl.—Eaperiments on Ocular Spectra produced by the action of the Sun’s Light on the Retina. By Sir Isaac NeEwrTon. Tue following very interesting experiments, though commu- nicated in a letter to Mr Locke on the 30th June 1691, and made many years before, were never published by their author, and were first given to the world in 1830, in Lord King’s Life 76 Sir Isaac Newton on Ocular Spectra, &e. of Locke. The similarity of some of the results to those pub- lished by the Editor of this work in the article AccipENTAL Cotours, in the Edinburgh Encyclopedia, is very remarkable. Although we have made numerous experiments on ) ocular spectra produced by strong lights, we have never been able to call up the impression by the influence of the imagination, in the manner described in the following paper, which is an ex- tract from one of Newton’s Letters to Mr Locke. . “ The observation you mention in Mr Boyle’s book of co- lours, I once made upon myself with the hazard of my eyes. The manner was this; I looked a very little while upon the sun in, the looking-glass with my right eye, and then turned my eyes into a dark corner of my chamber, and winked, to observe the impression made, and the circles of colours which encompas- sed it, and how they decayed by degrees, and at last vanished. This I repeated a second and a third time. At the third time, when the phantasm of light and colours about it were al- most vanished, intending my fancy upon them tu see their last appearance, I found, to my amazement, that they began to return, and by little and little to become as lively and vivid as when I had newly looked upon the sun. But when I ceased to intend my fancy upon them, they vanished again. After this, I found, that, as often as I went into the dark, and in- tended my mind upon them, as when a man looks earnestly to. see any thing which is difficult to be seen, I could make the phantasm return without looking any more upon the sun; and the oftener I made it return, the more easily I could make it return again. And at length, by repeating this without look- ing any more upon the sun, I made such an impression on my eye, that, if I looked upon the clouds, or a book, or any bright object, I saw upon it a round bright spot of light like the sun, and, which is still stranger, though I looked upon the sun with my right eye only, and not with my left, yet my fancy be- gan to make an impression upon my left eye, as well as upon my- right. For if I shut my right eye, or looked upon a book or the clouds with my left eye, I could see the spectrum of the sun almost as plain as with my right eye,* if I did but intend my, fancy a little while upon it; for at first, if I shut my right eye, and looked with my left, the spectrum of the sun did not * Though seen when the left eye was open, it may still have been the spectrum on the right eye.—Ep. Mean Temperature of New York, e. 77 appear till I intended my fancy upon it; but by repeating, this appeared every time more easily. And now, in a few hours time, I had brought my eyes to such a pass, that I could look upon -no‘bright object with either eye, but I saw the sun be- fore me, so that I durst neither write nor read ; but to recover the use of my eyes, shut myself up in my chamber made dark, for three days together, and used all means to divert my ima- gination from the sun. For if I thought upon him, I present- ly saw his picture, though I was in the dark. But by keep- ing in the dark, and employing my mind about other things, I began in three or four days to have some use of my eyes again; and, by forebearing to look upon bright objects, reco- vered them pretty well, though not so well, but that, for some ‘months.after the spectrum of the sun began to return as often as I began to meditate upon the phenomena, even though I lay in bed at midnight with my curtains drawn. But now I have been very well for many years, though I am apt to think, if I durst venture my eyes, I could still make the phantasm return by the power of my fancy.. This story I tell you, to let you understand, that in the observation related by Mr Boyle, the man’s fancy probably concurred with the impres- sion made by the sun’s light, to produce that phantasm of the sun which he constantly saw in bright objects. And so your question about the cause of this phantasm involves another about the power of fancy, which, I must confess, is too hard a knot for me to untie. To place this effect in a constant motion is hard, because the sun ought then to appear perpetually. It seems rather to cOdnsist in a disposition of the sensorium to move the imagination strongly, and to be easily moved, both by the imagination and by the light, as often as bright objects are looked upon. Art, VIII.—On the Mean Temperature of Twenry-Nine different places in the State of New York for 1829. Ix No. xvi. of this Journal, and in No. ii. of the New Series, we have given abstracts of the Returns of Meteorological observations made tu the Regents of the University of the State of New York for 1826 and 1828. Having been favoured by Mr Greig of Canandaigua with the Report for 1829, we 78 Mean Temperature of twenty-nine different places shall proceed to give an abstract of the observations it cons tains. The observations were made at the same hours as fondly viz. 6 a. m. three hours P. u. and an hour after sunset. The following table contains the position of the places of observation, and their heights above the sea, Elevation of N. Lat. W- Long. place of ob- above tide. Albany, ~ “ 42°39 "73° 4'7/ 130 © Auburn, 42 55 6 35 650 Cambridge, (Washington «6, 43 02 18° 22 Canandaigua, - 42 50 77 15 : tripe Cherry-Valley, - - 42 48 75 06 1335 Clinton, * - ~ 41 00 72 19 Dutchess, * - * 41 41 %3 54 Erasmus-Hall, “ “ 40 37 (73 58 Franklin, : - 42°30 77 133 Hamilton, = x 42 48 75 32 1127 Hartwick, - - 42 38° 75 04 | Hudson, i - 4212 3 46 150 Johnstown, 4 “ 43 00. 74 08 : Hongainy ° 41 55 ‘74 06 188 ansingburgh, - - 42 48 73 38 30 pase * 4Z 47 = ='T5 25 800 Middlebury, - : 42 49 78 10 800 Montgomery, - - 41 32 7410°— North Salem, - . 41 20 73 387 : Onondaga, Hi Joshi ue 43 02 7610. 410 Oxford, “ -. 42 26 75 38 961 Pompey, + - 42.56 7605 1300 Schenectady, - - 42 48 73 56 225 St Lawrence, : - 44 40 75 00 394 Union Hall, 2 -- 40 41 78 56 Utica, - - 43 06 75 12 4AT3 Washington, ~ - 438 08 317 Newburgh, ~ “ 41 30 74 05 150 In 1826 the mean temp. of 10 of the above places was 49°. 4 In 1828 the mean temp. of twenty-three places was 49 .99 In 1829 the mean temp. of twenty-eight places is only 46 .45 The following table contains the mean monthly tempera- ture of the twenty-eight places above-mentioned, the annual mean temperature, the annual range, and the highest and lowest during the year. & LIT 8e— 68 16 Wee 06 0 06 Bil $e— 68 ool 6 — 16 66 II— 88 SII SI— 86 66 s— I6 86 ¢— S6 «2 68 ¢€— 98 5 rolg— 86 ~ 96 + — 6 S O61 so— 66 Ss Wr.i— 296 %, 801 ZI— 96 ~ OOL II— 68 Ss oOo1r4.— £6 % 901 SI— 16 3 SII 0OZ— $6 S OLL #I— 96 a @- + 8 > oro— $8 I— 8 GOI gI— 16 06-0 06 91 ¢e— 16 6 9 = 18 301 OI— 3 aaj oS 'hP O09’ FF 1S°SP 90°bP LL'9% 6o'Sh 66°FP Ig°Lp 99°8% £9'0¢ 60'OF CS'9OF 8S'SP OL LY SSP 60'9¥ SO°6V 60'SR ShrP lO’ os'0¢ os Tg. vL'8h SS"bh 6o'9V 68°94 98°9F. 61's C6'bS 6S'0P 10°¥S 3° LS LOGE 98°S¢ 00'LE G6'8S 06°88 9F'6E 68°SS 98 z$ $6'8E ogo Le SL'Ss C388 60°98 8S°bS LYSE Loop 1o'TP OC SP 99°SS POSS Pl'OF TI3¢ ggg L8'1E OL'bs L698 L8°LE oL’8S GP'8S LOLE bS°oE PV'9S 96°98 6S°Lé $9°9S 19°0P ¥E°SS 69°VS Lost 68°8S 60'TP 90°0F PO'KS G1'98 6o°9 6g'98 OG Le 90°86 6Z'°9¢ 69'SP I8°'L¥ 19'0S 60°6% oF'09 08'9F 69'°LP 96°19 s6'1¢ 96°%S 8S°09 L8°0¢ 60'S 8L'0¢ 66°19 63S 60°IS G9'8h OI's¥ GS'8¥ 60°S S6'°9¢ 080g 00° LP Le'8h 6.'8F 880g c9'S¢ G0'GES or le o6'SS Legg SP ig 88°E¢ o8'S¢ OL'8¢ 68°59 13°69 ogg LESS IP'Lg LL's¢ Ig-¢¢ 9°09 G6'8S 90°89 G8'°SS cL’6g 61°19 LI'6¢ 69 '6o Si'Sog 62'%¢ 9L'99 9°F9 6°69 19°99 6°89 TL°S9 v8°99 13°89 OTOL 6FSL S9°IL 96°99 69°%9 o¢s'OL 08°69 43°99 oo'LL 08'g9 OL'69 1° LO g9°0L ZO'GL 61°89 PI'S9 86'L9 66°99 0s'L9 09°F9 Elle LL’SQ &&%9 GE'09 16°89 99°¢9 LL’L¢E 68°99 99°S9 E8'89 g9°b9 O8'L9 98"I9 08°69 6°39 88'L¢ £O'RO 1B°F9 S9'8E 91°L9 €L1°S9 86°S9 LL°69 G0'99 99°09 LG'GL 10°69 S6°S9 ¥6°69 6L°99 L9O°S9 IL'S9 O8'b9 $o'6¢ Lo99 LI-b9 OS'8S 9°69 $9°69 [0'°S9 02°69 36°L9 69-69 86°99 OL°F9 9BI9 g9°69 LOIL 8E°S9 1FS9 09°S9 80°89 98°89 Z6°%9 SI'S¢ 90°99 ZI'S9 L9°09 29°69 $99 86°69 62'SL 64°0L 66°F9 89°99 O1'Z9 ¢8"FS oVsg Slyg 69°89 61°69 6YS9 8TI'09 SL'L9 99°99 Lb6g 86'OP PLSY €9°9V SLOP L9’9% oO'lF 18°SF 69°6F L69F OL'6F 68'9P 18'9F O3'Sh o6'OF o6°LP G6 SP 99°8P FO SP ob'bP L8°bb 89°Sh gl’a¢ OF'hP Lot 68'OP 88°SF 10'sg 9I'LO 64'L9 19°S9 0°09 Lob L6°89 L989 GI'89 SHO OL'SP 03'8h ob'9S GI'6E LOIS POLS a iP A g g q oH 5 i e 5 ? > E LOLS 1S'1lS Pl Lo 99°36 L0°86 60°0% LESS S8'SS 66°93 Oh'8S $9°9G LOSS 9L’9I SI'SS 96°96 89'0% CS'SS bG'SS S1'Ss 99'°0% 96'0E SPSS 68°66 OL’6r 61°0E FLOS OLl’sé 6E°LS o6'Ig 8a LS Le63 0g'Ig POPE O6°FS POSS 98°63 19°93 PSOE 1L'08 86°63 80°38 $o'0s 1h'83 L¢'66 Go9E 69°96 PL'SS 0$'SI SL'ST GI'SS 9OL'SI SL'st 09°91 86ST 08'3S 69'LS L8°3S 96°1% 69°6I 89°ST 96'8T LL'lG os'st 98°61 Co'6I 06'0% SSI 66°SS OSS ~8°SS 9°96 FL’ST IL':0g 19°61 60°FS G0'0s LELI 80°%s L663 93°6I GO'Ss o6'ss 96°61 LH'Sss ua e a = ‘ ‘uoySuryse AA 2 ‘won) ‘TeH-uoruy ‘20UdIMP'T 1S ‘Apeyauayog ‘fadumog - _ *piojxo - ‘‘eZepuoug ‘ys.nqaon “wiaTeS -T}10 | ‘AramoSyu0 py ‘£anqe[ppi wl = ‘a[[AMoT ‘qSimqsuisue’y - ‘uoysSury ‘UMO}sUYyO c * ‘uospnyy - “yorazae py - ‘uozpTUIe FT - “uypyuery Te H -snuser - ‘ssayojng = “wozuTT ‘Kage A -Ar19y9 ‘enSrepueurd ‘aspriquiesy - ‘aanqny - Aueqiy *satmIapvoy 80 Mean Temperature of twenty-nine different places The following table shows the quantity of rain and snow which fell in the state of New York in 1829, vig In. Albany, - 38.07 Auburn, © - 30.54 Cambridge, Washington 39.04 Canandaigua, - 30.20 Cherry-Valley, - 39.93 Clinton, - 42.56 Erasmus-Hall, -. 48.62 Franklin, +, = 1 26:16 . Hamilton, ~ 33.26 Hartwick, * 40.83 rea 33.47 Johnstown, ‘ 36.59 - Kingston, - 38.99 Lansingburgh, Lowville, Middlebury, Montgomery, Newburgh, Onondaga, Oxford, Pompey, Schenectady St Lawrence, Union-Hall, Utica, In 1826 the mean rain of nine places was In 1828 the mean rain of twenty-five places was In 1829 the mean rain of twenty-five places was MIscELLANEOUS OBSERVATIONS. Aurora Borealis noticed. Jan. 27, at Cambridge. Jan. 30, at Cambridge. Jan. 31, at Cambridge. April 4, at Utica, - April 5, at Lowville. ° Mean, In. 38.34 28.07 29.80 (31.45 $2.54 27.01 36.71 27.23 $4.85 27.71 45.83 - 36.16 Inches. 56.34 36.74 34.88 35.96 April 8, at Lowville, resembling a bright cloud, and: exhi- biting near the horizon, a steady light of several hours’ con- tinuance. May 29, at St. Lawrence. May 31, at Schenectady, Utica. June 1, at Cambridge, Franklin, Middlebury, Pompey, Utica. eet Very brilliant, appearing in distinct ares, one above’ in the State of New York. 81 the other, the highest subtending an oor of about .'75°. {St Lawrence.) — - June 2, at Cambridge, Utica. - June 7, at Schenectady, brilliant all night. - June 14, at St Lawrence. June 21, at Poughkeepsie. © August 25, at Poughkeepsie. August 26, brilliant, at Auburn, Cambridge, Schenectady, Utica. Sept. 18, at Albany, Poughkeepsie, Utica. Sept. 19, at Albany, Clinton. Describing an are on the plane of the horizon, of about 65°, and rising in distinct spires towards the zenith. Noticed between 8 and 11 p.m. at St Lawrence. - Sept. 26, About half-past 9 rp. m., a brilliant aurora bo- realis was observed. It was cia cine of beams occasionally shooting up as high as the pole star from a point of the hori- zon, a little to the west of the true north, at Albany. Oct. 21, brilliant, at Cambridge and Utica. Oct. 24, at St Lawrence. - Oct. 27, About 8 v. m., three perpendicular columns of light appeared in the north, the central one extending about 20°, and the two external about 15° above the horizon, at Delaware. Nov. 9. At Lowville, with brilliant and brisk coruscations. — -‘Half-past 4 a. m. Nov. 19, at St Lawrence. Faint, with ‘occasional spires ex- tending towards the zenith. Dec. 19, at Schenectady. Dec. 28, at evening, between 7 and 8 o'clock, several per- sons observed a light in the west, a little south, proceeding in rays from a centre, and shooting sparks so bright, that the trees could be distinctly seen at Hartwick. Aurora borealis very brilliant at North-Salem. Haloes, &c. —March 15. An extraordinary halo round the stm at half-past 5 r. m. Next to the sun was a coloured circle, whose diameter was equal toa chord of 30° of the sensible horizon, At the north, south, and east points of this circle were luminous spots of considerable magnitude, the west. part of the circle was below the horizon. North and south of the NEW SERIES, VOL. IV. NO. 1.JAN. 1831. F 82 Mean Temperature of twenty-nine different places sun (one on each side) were two arcs of a circle, answering to a radius, about twice as great as that of the inner circle. These larger arcs were coloured, as the rainbow, the red be- ing next to the sun.. East of the sun or above it, and at the same distance therefrom, as the north and south arcs, was ano- ther arc coloured like them, (though less bright) but mani- festly convex towards the sun. Directly between this last mentioned arc and the sun, and externally tangent to the east- ern part of the inner circle, was a luminous and broad para- bolick curve. Lowville. - April 8. Halo round the moon, at Pompey, Utica. May 15. Bright lunar halo, at Utica. June 8. Brilliant circle round the moon, at ul P. M., with a mock moon on the right of the circle, at Utica. Sept. 2. A brightparhelion seen near sunset, about 8° from the sun, at Erasmus-Hall. Sept. 9. A beautiful large halo round the moon, at Delaware. Nov. 6. Large lunar halo, at Lowville. Dec. 2. Lunar halo, at Lowville. Dec. 30. Lunar halo, at Cazenovia. Meteors.—June 14. A splendid meteor noticed about 8-. m- at Delaware. Bright meteors seen at Hartwick. Oct. 2. A meteor passed from north to south, 6 P. M., at Erasmus-Hall. Meteors seen S. E. before dark at Hartwick. Oct. 5. Brilliant meteors passed N. W. to S. E. 6} pv. m., a little east of the meridian, apparent size about 9 inches, at’ Erasmus-Hall. . Oct. 24. A brilliant meteor seen in the east at an angle of 40° above the horizon. It moved south, and in a few seconds disappeared. Lansinburgh. A bright meteor passed at 10 P, m., easterly of the village from north-east to south-west. Utica. Storms, &c.—On Sunday, the 12th July, at three o’clock, while the bells were ringing for church, a storm of wind and rain, accompanied with some thunder and lightning, from the south-west, passed over thecity. . This storm is worthy of no- tice, particularly i in relation to an observation made by Dr | Franklin, that in this country all the N. E. storms, begin first in point of time in the south-west; or, in other words, that the progress of the storm, over the face of the country, is in a di. im the State of New York. 83 rection opposite to that of the wind at the time. According to the New York papers, the above-mentioned storm was much more violent in that city than in Albany ; ; and began some time after the preaching of the sermon in the different churches had commenced. It must therefore have happened between three quarters of an hour, and an hour and a-half, later at New York than at Albany. Dr Franklin concluded that the storms observ- ed by him, receded in this manner about one hundred miles in an hour. [See Franklin’s Works, vol. 3, page 284.] Albany. Sept. 25. Two thunder storms, p.m. On the same after- noon, the papers mentioned a violent thunder storm passing over part of Dutchess county, which killed a number of sheep. —(Albany.) _ Some.time in the latter part of September, there was a vio- lent tornado in the north part of this and the adjoining town of Fenner. Its course was about S. E. by S., and its extent ten or twelve miles. Many out-houses were overturned or unroofed, trees, three feet in diameter, twisted off, and large limbs hurled five or six hundred feet in the air. Its path, the whole of the above distance, was visible by its effects when I visited it some two months afterwards. In some parts, it urg- ed its way through stripes of woodland, leaving nothing but an occasional tree dismembered of its branches,—in others, it was more elevated, as was determined by the limbs of trees and dust carried with it, and consequently less destructive. It succeeded a sudden change of the wind from south to N. W. by west.—(Cazenovia.) Rain and Snow.—June 22. During 28 days, less than } of an inch of rain has fallen.— (Canandaigua.) Oct. 5. A rainbow appeared in the N. E. from clouds which brought no rain.—(Delaware.) Feb. 25. Snow three feet deep in the south-west part of this town.—(Lowville.) Winds.—The situation of Homer village, in a long and somewhat deep valley, produces a fluctuation and incessant vacillation of the currents of air, such as I never witnessed 'i in any other place. To give an example : in the morn or evening, it would be no unusual occurrence, in looking at half a dozen vanes, or the 84 Mean temperature of twenty-nine different places, &e. smoke adoonieia from as many chimneys, to see them veering in as many different directions at the same moment; and all this within thirty rods distance of the observer. Such a va- riety may be seen almost any day, and, occasionally, at any time in the day; but is most frequent near the time of sunset or sunrise. So that when the current is strong and steady, perhaps all the day, on the neighbouring hills, either east or west of us, a person in this vale would be utterly unable to pronounce from what point of the compass the wind was that moment blowing, in a general course, in this section of the country. From four years’ experience and much observation on. this subject, in this vicinity, I am well assured, that while upon the high grounds in this region the wind is blowing steadily from the east or west, the currents are here between 8. E. and S. W., or between N. E. and N. W. In the greatest severities of weather in winter, even when the mercury stands below zero in Fahrenheit’s scale, the moyve- ment of the air in this valley is almost imperceptible ; but when perceived in the morning, its course is almost always from the S. or S. W. Such a phenomenon I never noticed in any other place.—(Cortland Academy.) The prevalence of westerly, and the entire absence of north- erly winds at Utica, is explained by an attention to the fea- tures of the country. Our observation must first be directed to the vast extent of level country surrounding and stretching far west and north of lake Oneida; over which the prevailing winds of our country, the west and north-west, sweep without any particular obstruction, till they are compressed by the high hills of the Black river country on the north, and the hills on the westerly and southerly side of this lake, approaching near each other in the towns of Floyd and Rome, or Whitesborough; and forming a deep opening or gap, through which runs the Mohawk valley, in a direction a few degrees south of east. Immediately on passing this gap, opens to the south, the ex- tensive vale of Oriskany and Saquoit, which may be termed the Oriskany basin ;—bounded on the west by the high hills to- wards Augusta, and on the south by a chain of hills extending from Madison county, m an easterly direction, to the river Dr Hibbert on the Diluvial Wave, &¢. 85 Mohawk, at a point a few miles below the village of Utica, and rising to an elevation of more than a thousand feet. The northerly side of this basin is bounded by the Floyd hills, which extend with a bold elevation along the margin of the Mohawk to some distance below Utica. The current of wind after entering the Oriskany valley spreads in a southerly di- rection, till on reaching the barrier on the south, it is reflected to the east, and continuing its course along the hills by the village of New-Hartford, it passes the village of Utica, situa- ted almost in the south-eastern extremity of this basin, in an easterly direction; cutting the Mohawk valley a little trans- versely, till it passes through a second gap, a few miles below. Hence the winds, which in other parts of our country are cal- led north-west winds, and which blow so uniformly from that direction when not particularly obstructed, as in this place, that they constitute a distinguishing feature in the climate of our country, are in this part of the Mohawk valley, almost unknown. For similar reasons a north-east wind is seldom ob- served.—(Utica.) . Temperature of Wells.—Examined in August, 51°.—(A lba- ny-) In September, 51°.—(Albany.) Examined Sept. 2, at 3 P. m., stood at 49° in a well eighteen feet deep, and the thermometer immersed ten feet beneath the surface of the ground. On the following morning, at sunrise, the thermometer in the same situation remained at 49°.— (Lowville.) Art. IX.—On the Direction of the Diluvial Wave in the Shetland Islands. By 8, Hissert, M. D., F.R.S. E., &e. ’ Communicated by the Author. Ir we would estimate the more important direction of the di- luvial wave, which, in sweeping over the less elevated lands of the British Islands, has dispersed an immense mass of clay and boulders far from their native beds, it has often struck me, that the most satisfactory investigations might be expected from the appearances presented in the north isles of Scotland, where the course of the wave would be less likely to be mo- dified by such causes as must have conspired to change its direction in encountering the headlands of more southerly 86 Dr Hibbert on the direction of the ‘coasts. I regret that, when twelve or thirteen yesrs ago, I made a minute survey of the Shetland Islands, the geological questions which transported boulders involved had then little recommended themselves to the attention of geologists; whence I was less disposed to pay attention to such sites favourable to their deposit as were likely to convey the information which “might be desired. At the same time, several diluvial indica- tions were not quite lost upon me; and when Dr Buckland had made public his interesting speculations on this subject, I has- tened to reperuse the notes which I had made four or five years previously. ‘These I shall make the foundation of the ‘present paper. I would, however, previously observe, that if we here seek for the large diluvial deposits which are to be found in Eng- land or Scotland, we shall be much disappointed. ‘Such beds of very deep depression as might be conceived favourable to the detention of transported fragments are concealed from human investigation by the deep voes or inroads of the ocean. It is therefore from the presence of the transported relics which more sparingly occur on the sides of declivities, or are strewed upon the higher plains, that we can infer the evidence of a di- luvial wave, and can speculate upon the point of the compass whence it had its origin. The following, then, are the facts which led me to infer the more important direction of thediluvial currents, which, as [have stated, swept over the less elevated lands of the British Islands ; —I say less elevated lands, from the belief, that the wave failed in overtopping the summits of very lofty mountains. In examining the Island of Papa Stour, situated on the west of the Shetland groupe, I was struck with the fact, that, though this small spot, of about two or three miles in length and breadth, is composed of sandstone and secondary porphyry, numerous fragments, even in the interior of the island, might be found of a peculiar and very beautiful hornblende schist and actinolite schist, which is no where to be met with in this archi- pelago, except at Hillswick Ness; a distance, when measured in a straight line across the Bay of Saint Magnus, of at least twelve miles. I also found, that, besides these fragments, relics of other distant primary rocks were strewed about, less easily, — Diluvial Wave in the Shetland Islands. 87 hhowever, to be identified than those which I have described. ' At first I was inclined to believe that these transported mate- rials might have been due to the inhabitants of Papa Stour, who brought them over as ballast, &c.; but this suspicion was ‘not only discountenanced by the contradiction of the natives themselves, but was in other respects a most improbable con- jecture, particularly from their being found in the centre of the islet, a mile’at least: from the water’s edge, as well as from their quantity, which was far too considerable to be referred to such a cause. The observations made by Sir James Hall on the Scottishdebacle, as well as those of Saussure on the detached boulders of the Jura Mountains, then suggested themselves to my mind, and I had the wish to record the fact; but, being aware that I had not hitherto pursued this particular investi- gation to the extent that it deserved, I waved for the time the intention I had formed. Nor, indeed, do I publish at: the present day the detached observations which I had made, ex- cept as a hint to promote the research of some future visitor of the northern islands of Scotland. On the supposition, then, that I am correct in referring these fragments to a removal by diluvial causes from Hillswick Ness across the Bay of St Magnus to the Island of Papa Stour, the diluvial wave which transported them a distance of twelve miles must have propelled them from a point of the compass bearing from their place of lodgment about N. 47° E; and hence, if we suppose a very distant prolongation of this _~ line of bearing, it would nearly fall in with the north-westerly bounding line of the Norwegian coast. A suggestion of some importance is thus afforded for the future inquiry of the geo- logist, im connection with the curious fact, that no little share of the diluvial boulders observed on the coast of Yorkshire, has been assigned to the transported materials of Norwegian rocks. Such are the phenomena which incline me to imagine, that the great diluvial wave which swept over the low elevations of the whole of Scotland and England had in the latitude of Shetland a north-easterly origin, or, in other words, that it had a south-westerly direction. This conclusion may receive some additional support from another appearance which I haye given in my Description of 88 Dr Hibbert on the direction of the - Shetland, without, ‘however, hazarding an explanation: of it. I have there stated that about a mile or two to the north of the mansion of Lunna, on the east of Shetland, are to be found several remarkable detached rocks, named the Stones of Stefis, the largest of which was about twenty-three feet in height and ninety-six in circumference.—Now, regarding these astonish- ing fragments, I did not then venture to express a decided opinion ; I merely observed, that, in the first place, they did not seem to have undergone any very distant removal, since they reposed on rocks of precisely a similar kind; that, se- condly, they did not appear to have been loosened from rocks of a greater altitude ; and, ¢hirdly, that, if we were inclined to consider them as the detached remains of pre-existing masses, having escaped a decomposition by which the rest of the rock of which they had formed a part had been removed,—we should still be compelled to admit that a disintegrating process of this nature must to‘any great extent have long since ceased, since the gneiss in question was little prone to decomposition. Such was the guarded language in which twelve years ago I described an appearance upon which I should now be dis- posed to pronounce with some degree of confidence, These immense boulders are to be found in an elevated situation up- on a very narrow tongue of land, three or four miles in extent, which, having jutted out into the ocean in a north-easterly direction, would be opposed to the direct force of the diluvial wave. The extremity of the headland being much broken, an indication is thereby afforded of the site whence these stones have been dislodged, and by diluvial currents in a south- westerly direction hurried along. The distance, however, to which they have been detached cannot be estimated at the most more than a mile or two; nor is it reasonable to give to the diluvial power an almost incalculable force, or to conceive of its effects without assigning to it due limits. We must re- flect that we are contemplating displaced fragments of the height of ‘twenty-three feet, and of nearly a OS breadth, But, besides these dikirvial indications, many others enighé be found, though they are perhaps scarcely of equal weight with those which I have described. Diluvial Wave in the Shetland Islands. — 89 On’ some parts, for instance, of the east coast of the Island of Yell, which is composed of gneiss, many large fragments may leilbtbcted of serpentine and euphotide, which have evi- dentigibeen drifted some asides from the islands of Unst and Fetlar- Again, in ascending the hill named Roeness Hill, composed of red granite; which has an elevation of 1447 feet above the level of the sea, I was struck with the immense quantity of boulders of a primary greenstone or trap which appear to have been removed from a:site two or three miles off, and to have been rolled in a southerly or south-westerly direction up a — dual ascent of three or four miles. On the summit of Hillswick Ness, also, we meet with a sure prizing block, mantled from age with grey moss, which is — composed of a granite removed from a rock, the nearest site of which is about two miles north. It is far too large to au- thorize us in supposing that it was transported from its bed and rolled up this high hill by the ancient inhabitants of the country. It is many feet in dimensions, and every thing which the ancient inhabitants were likely to effect would be to place it on an edge previously to the dedication of it to The Thunderer. This Thorstone, as it was anciently called, evi- dently owed its original displacement to diluvial torrents. Lastly, I may remark, that it is possible to find in Shetland some fragments of stones which are strangers to the country, and which have probably been transported from foreign shores. This is the case with some detached boulders which we meet with in Soulam Voe, an unsheltered harbour open to the Nor- thern Ocean. One of these, to the best of my remembrance, about three or four feet high, is a variety of granite, quite un- known in the country, which probably had its upright position given to it by: human exertions. Its distant emigration even vulgar tradition has recognized, by affirming that it was thrown here by the devil,:as he stood on some high hill in a neigh. bouring parish. I shall not trouble the reader with any more proofs to show that the influence of diluvial currents was experienced in the Shetland Islands. I cannot, however, avoid remarking, that it would be interesting to inquire if indications of the presence of the diluvial wave, and of its south-westerly direc- ge OA abs oh tah ees shila. 90 Dr Hibbert on the direction of the Diluvial Wave, &c. tion, are afforded in islands even north of Shetland. I have not visited Feroe, ‘and can therefore only express my opinion in the affirmative, from the following remark of Landt in his account of this country. ‘‘ Besides the large collections of stones,” he observes, “* already mentioned, which are occasion- ally found on the hills, there are seen sometimes in the vallies single stones, six, eight, or ten feet in diameter, but in places where it is impossible they could have fallen down from the hills. Such stones are found also here and there at a consi- derable height on the hills, where there, is no other eminence in the neighbourhood from which they might have rolled down. On the sides of many of the hills, and particularly on the lower projecting declivites, there are often found great heaps of stones, among which there are some large ones; but it may be plainly perceived that these have been thrown down from the higher projections, in the fissures of which the rain water lodges, and when it freezes in winter it splits the rock by its expansion, and on a thaw taking place these fragments tumble down, and by their fall destroy the green plots below. But the stones thrown down in this manner are different from those before mentioned ; for the latter have two sides, which stand at a right angle, or, at least, they have one or more flat surfaces, whereas the former are in general round.”——Landt’s Description of the Feroe Islands. Trans. London 1810, page 8. .. The foregoing is a most interesting notice, and quite suffici- ent to excite the attention of the geologist who shall hereafter visit this archipelago. Nor will a similar inquiry in Iceland be probably less interesting. ‘ehtivs Having thus endeavoured to show the probability that the great currents which deluged the British islands, as well as some parts of the continent, had in Shetland a north-easterly origin, or a south-westerly direction, I might, as a continua- tion to this account, endeavour to point out the modifications which the wave underwent in its direction during its progress farther south. This would, however, lead me to a very ex- tended inquiry; nor have we yet sufficient data for the pur- pose. ‘lhe modifications in the direction of the diluvial wave in Yorkshire have met with some notice by Mr Phillips;:and I might os Nl Mr Forbes on Barometric Instruments, &c. 91 mention, that, on the north-west coast of England, the nume- rous fragments of rocks which have been propelled from the neighbourhood of the Lakes in Cumberland, and dispersed over the low lands of Lancashire and Cheshire, show that the cur- rent in its progress through the Irish channel, after having en- countered the various headlands of Scotland, England, and Treland, has had its direction changed from a south-westerly toa south or south-easterly course. But, for the present, I quit the prosecution of these researches. It is possible I may resume them on another opportunity. Art. X.—Memoir on Barometric Instruments acting by Com- pression, considered particularly in their application to the Measurement of Heights ; including some new Trigono- _ metrical Determinations. By James D. Forses, Esq. Com- municated by the Author. Pant I.—On the Defects of the Sympiesometer. My former paper in this Journal for April 1829, upon Mr Adie’s sympiesometer, contained the results of some long pre- vious experiments, among the first, indeed, of an analytical character which I ever undertook in physical science. I con- sidered that they carried with them sufficient proof of their general accuracy, from their bearing out so completely in their details the theory of an error, which in making them was not even remotely in view; but I obtained very speedily a confir- mation of the results I had arrived at, from a source ‘every way satisfactory. After my paper was in the press, Dr Brew- ster kindly communicated to me two very interesting letters from Professor Schumacher, the distinguished German astro- nomer, written more than eight years ago, and complaining of the very same defect as I had indicated.. What is more re- markable, he suggests the identical mode of correction which I proposed in my former paper. This may be seen) from the sketch in Plate I. Fig. 6, which is a fac-simile of Professor Schumacher’s. _ Having been induced to revive my old series of observations, which for some years had been laid aside, I was naturally de- sirous to re-examine the sympiesometer, and to verify them 92 Mr Forbes on Barometric Instruments under a variety of circumstances, especially as they had been depreciatory of an instrument of acknowledged elegance and ingenuity. I need hardly say, that [had no reason to change my opinion as to the correctness of my original observations, otherwise I should, long ere this, have acknowledged my mis- take ; but the views which are to be developed in this paper would long since have been published, (indeed they were in some forwardness a year ago,) had not the investigation, at first apparently simple, extended itself so much on all hands, and, by being considered both in frequent practice and rigid theory, opened so many questions for solution, that, even had the ob- servations been sufficiently accumulated for the purpose, I could not till now have found leisure to reduce and classify them. » Having got my sympiesometer put into thorough repair by Mr Adie, I commenced regular observations with it in May 1829, and since that time have made at least two thousand ac- curate and recorded observations, with proper data for com- parison and correction. Perhaps it may be asked whether the instrument was worthy of so much labour, especially as the de- tection of its inaccuracies was the principal object of my in- quiry § ? But it is a sufficient reply to observe, that I began to perceive germs of excellence in this species of barometer almost as soon as I recommenced my inquiries, and likewise the means of obviating its defects, so as to render the ascertainment of these an object of primary importance. The confined situa- tion of the ravine which was the scene of my first experiments, was so far fortunately chosen, that it showed strongly the sources of error of which I was in search, (and which will be shown in the course of this memoir to have been independent of the defects of the spot for measurements by the common barometer) ; but experience proved, that in favourable situa- tions, and under favourable circumstances, these errors, though never null, are often greatly reduced ; and the want of porta- bility in the mountain barometer, which, after much conside- ration, I begin to think an ividitutoaitititble evil, certainly re- flects no small merit upon an instrument which could supply its place, with a degree of commodiousness to which I can bear ample testimony, having made it the constant companion of acting by Compression. 93 iny hilly walks and geological excursions, alike under a mid- summer sun, or among December snows. This alone, had its defects been more insurmountable in appearance than they are, would have furnished me with a sufficient motive for prosecut~ ing my inquiries : it farther requires no stand, the steadiness of which in the barometer renders it a most cumbrous appen.« dage, and it readily bears shocks which, from the weight of mercury in the latter, would at once prove fatal. My extended experiments with the sympiesometer not only enabled me to observe the nature of the stations where it was best calculated to act, and in which the locality of my first ob- servations was peculiarly unhappy, but they pointed out the practical artifices by which the errors might be reduced toa minimum. I found, as might be expected from the theory I developed in my former paper, that a free current of air of equable temperature, and the absence of reflected heat, was of paramount importance; hence the instrument performs much best on insulated summits and in cloudy weather. I have found an umbrella stuck into the ground by far the best sup- port, furnishing a useful degree of shade from direct sunshine. When approaching a station I swing the instrument freely at some distance from my body, in order to permit it nearly to acquire an equality of temperature in its different parts, before fixing it for observation. The observations too, which will hereafter be detailed, had generally the very important advan- tage of having the horary variation between leaving and return- ing to the lower station, ascertained or corrected by the baro- meter. But these topics belong rather to another part of this memoir. Let us, in the first place, and before proceeding to details, notice briefly, for the benefit of those less familiar with barometers acting by compression, their history and most im- proved construction. Considerably above a century ago, Dr Hooke seems to have thought of applying the error of the air thermometer occasioned by pressure, to the measurement of that source of irregularity in its motion, by the simple means of eliminating the effects of temperature, for the measure of which the instru- ment had at first been solely adapted. This was readily accom- plished by attaching a thermometer acting by the dilatation 94 Mr Forbes on Barometric Instrumenis of non-elastic fluids: The value of the barometer as a progs ‘nosticator of weather has been sufficiently known to render it an object to introduce its use at sea, which Hooke accordingly proposed ; and his instrument, like all others which indicated the density of the air under the combined influence of tempera- ture and pressure, was called the Manometer, a name which, perhaps, it would be well to retain. Halley afterwards mention- ed this instrument with applause, * and stated the objection which had been found to it from the absorption of the inclosed air by the confining fluid. Varignon seems also to have con- trived a manometer similar to Hooke’s. + The objection arising from absorption was got over, though certainly at the expence of the simplicity of the instrument, .by using mercury for the confining fluid in a manometer hastily got up for the Arctic Expedition of Commodore Phipps, ‘by Mr Ramsden; and from the account given of its perform- ance under very unfavourable circumstances, we are led to wonder that it should once more have fallen into oblivion. In the account published of the voyage it is said, ‘* This instru- ment, though far from complete, having been constructed in a hurry, for the purpose of a first experiment, and liable to some inaccuracies in the observations, from not having the thermometer with which it was compared attached to it, sel- dom differed from the marine barometer one-tenth of an inch. Should it be improved to the degree of accuracy of which it seems capable, it will be of great use in determining refractions for astronomical observations, as well as indicating an ap- proaching gale at sea.”t I shall not notice the manometers of Roy § and Davy, || which were intended merely for labora. tory experiments; but pass on to the sympiesometer of Mr Adie, of which, (though from not knowing what already had been done, he had the merit of the invention,) the real novelty consists in finding means of preventing that absorption of air by the inclosed fluid which occurred in the instrument of * Philosophical Transactions, vol. Xxii. p. 791. + Mémoires de l Academie Royale, 1705. + Phipps’ Voyage towards the North Pole. ~ Appendix. § Phil. Trans. vol. Ixvii. || Nicholson’s Journal, Svo. vol. iv. acting’ by compression. 95 Hooke, without employing mercury, as was done by Ramsden. This he found to be effected by using almost any gas but at- mospheric air, excepting such as happened to be immediately absorbable by the inclosing fluid.* To enable those not inti- mate with the instrument to follow the succeeding details, I shall give a figure of Mr Adie’s sympiesometer in its most improv- ed and portable form, such as I have always employed. It is in- closed in a brass cylinder, which is contrived to close upon itself. A glass tube BC, Plate I. (Fig. 7,) of considerable length, terminates above in an elongated bulb inclosing hydrogen gas, and the lower part being filled with oil as an indicator of the bulk of the gas, terminates in a cistern D, provided with a ~ Me stopple pushed down by a pin at I. The bulk of the gas in. the bulb A, being affected both by temperature and pressure, the former is eliminated by moving the zero of the sliding- © scale G H, down to a point on the pe ORS. F, (graduated for the effects of temperature only,) which is determined by the ° attached delicate mercurial thermometer E.. The barometric indications are simply indicated on the sliding-scale. In this part of the memoir, I propose to lay aside as much as possible theoretical considerations, and, taking the sympie- someter as the most improved form of manometric instruments, to examine its practical defects. A complete investigation of the theory of these imstruments will be given in the sequel, with a consideration of the mode of graduation, in which, I believe, the sympiesometer may be materially improved ; and I shall then detail the new forms of the instrument which I pro- pose for the diminution or correction of the present errors. These errors, which it is the object of the present paper to ex- amine, are of three kinds,—one arising from an inherent inac- curacy in the scale of the instrument, and capable of estima- tion; another of continued and variable decrease in the ab- solute pressure indicated, and the third, variable and irregular, depending upon external circumstances. Each of these must be separately considered. * The absorption complained of cannot be of a merely mechanical na- ture, otherwise it would arrive at a speedy limit. Its phenomena seem to have been little attended to. Mr Leslie found at first similar difficulties im the construction of the differential thermometer, which he successfully removed by the employment of sulphuric acid,—a fluid which would not answer in the present instance, where one portion must necessarily be ex- posed to the free atmosphere, from which it rapidly attracts moisture. 06 Mr Forbes on Barometric Instriiments § 1. On an Error in -the Graduation of the Sympiesomeéter. To understand this rightly we must have recourse fo a lit- tle of the theory of the instrument. ‘The elastic fluid in the gaseous bulb is affected in its bulk by temperature and by pressure. ‘The effect of increase of temperature is by dilata- tion to enable the gas to occupy a larger space under the same pressure, or, in other words, to increase its elasticity. Thus, if a volume of gas under a pressure of 30 inches of mercury be represented by 1, and by an increase of temperature, its volume becomes 1.1, it will yet support the same pressure of 30 inches. Now taking in the element of pressure, we know from the law of Mariotte, that the volume of an elastic fluid is inversely as the pressure it sustains; therefore, as the pres- sure sustained by the gas at both the temperatures above sup- posed was 30 si i the volume at 29 inches would, in the first case, be 1 x 3%, in the other 1.1 x FS. OF 2% and § oP and subtracting the volumes as affected by temperature simply from each, we have for the extent of scale corresponding to a change of an inch of pressure, in the first case, 39 — 1 — |, ; : 11 . in the second 33 —1.1= 5 Hence, every volume assumed by the gas on account of a change of temperature must be considered as a new unity of volume, and to each a different scale of inches of pressure belongs. Therefore, no sliding scale can satisfy the condition of the problem,—a circumstance overlooked by Mr Adie, as his mode of graduation sufficient- ly proves, which consisted in placing the instrument under varied circumstances of temperature and pressure respectively, the other element remaining constant. We may investigate this more concisely by symbols, and those employed by M., Biot* are as convenient as any we can use. Let V represent the volume of gas at the freezing point, and under a pressure p; and V’ that at a temperature ¢ de. grees above’ the freezing point, and under a pressure p’; ¢ being the dilatation of gas for 1°, the unity of volume being * Traite de Physique, tom.1. It is a frequent defect in inquiries like the present, that the investigations given are wholly popular, or wholly mathe- matical. Both should be given where detection of error is the object, for conviction is most effectually brought home to some by the one method, and to some by the other; and it would save some errors in theory did the analyst oftener condescend to clothe his argument in eel where the subject is one of proof, not of discovery. acting by Compression. 97 at the freezing point. Then from the laws above-mentioned we hava . age wey, (1 + 8t).2 but where the Laeset of pressure and temperature are taken se- parately, as employed by Mr Adie, we have V’ = V. C + 6t), the error of which consists in the omission of the offect of changed pressure upon the excess of the new volume caused by the alteration of temperature, or in employing 6 ¢ asa mul- tiplier, in place of “3¢. As in Hooke’s instrument, like Adie’s, a sliding scale was used, it was liable to the same er- ror, which in Ramsden’s was avoided by the substitution of calculation for a sliding scale. We may in the meantime state that the correction in round numbers amounts to the increase of the barometric divisions on the sliding scale, by one hundredth for every 5° of excess of temperature above that for which the unity of volume was taken. § 2. Ona gradual change in the absolute Height of the Sym- piesometer. While by the principles of construction of the sympiesome- ter it was conceived to be freed from all index error, by the author of the article Meteorology in the Edinburgh Encyclo- peedia, it was thought that the absorption of the inclosed air which spoiled the instrument. of Hooke had not been got free of, and that an additive error gradually accumulated ;—the production of extensive and satisfactory experiments will justly be considered necessary, if I shall assert the existence of a con- trary error by which a gradually decreasing pressure is indi- cated. Thetable in the article Meteorology, just referred to, was merely given as pointing out a general tendency to an ad- ditive error, and the comparisons with the barometer were only continued for a short period. The cause of the apparent ad- ditive error in the sympiesometer is probably mainly attribut- able to the effect of temperature on the barometer, which we have no reason to believe was corrected; and as even in the most constantly inhabited rooms, the temperature falls several degrees in the months of October and November, when these observations were made, the uncorrected height of the baro- NEW SERIES, VOL, IV. NO. I. JAN. 1881. G 98. Mr Forbes on Barometric Instruments meter being lowered, the apparent deviation of the sympiesome- . ter would have an additive sign, supposing it stationary... | When, in April 1829, I had my sympiesometer repaired by _Mr Adie, I found the index error to amount to — .08 inch, . at a temperature of 60°. The cause of this discrepancy I shall not at present inquire into. In doth his instruments, Professor Schumacher found it to be + .14, at 50°, In a notice I have met with of the sympiesometer, as used in the Russian service, I find the index error stated at as much as — .60. * Being desirous of examining not only the constancy of its level, but its general performance and supposed great sensibility, I imme- diately commenced aregister of comparison of the sympiesometer with the barometer. Being then engaged in an inquiry, which for some years I have been carrying on, into the horary oscilla- tions of the barometer, I compared the two instruments every time I observed the latter, or five timesa-day. This extensive register was pursued with slight interruption, till August 1830, sail presented an ample collection of facts and data, amount- ing to many hundred observations, of which the following pages present an abstract ; each individual observation having registered along with it the temperature by the attached ther- mometer of each instrument. That attached to the sympie- someter having been broken in August 1829, a difference of a few tenths of a degree might alter the indication of index error. T have therefore commenced my reduction of the observations with their resumption in October. I have contented myself with reducing the first five days of copious comparisons in each month, so as to show the index error at these intervals as far as till March in Table I.; but after March I deduced daily the mean results of all the comparisons ; a practice which can- not be too much recommended ; and I have given them in full. I will therefore only request the reader to observe, that though he finds comparisons given for every day in Table II. these are not insulated observations, but generally the result of five comparisons, and deserving of proportionate weight. He will therefore suspend his judgment as to any oscillatory irregula- rities which appear from one period to another; and confine his attention chiefly at present to the general results of the monthly comparisons. In Table I. the successive columns present, 1st, the day of the month ; 2d, the barometer ; $d, the * Admiralty Memoirs of St Petersburg, vol. x. acting by compression. 99 attached thermometer; 4¢h, the height of the barometer re- duced to’ ; 5th, the sympiesometer ; 6¢h, its attached ther- mometer ; | th, the index error of the sympiesometer, or the difference of columns four and five. In Table II. for concise- ness, column four is omitted ; and the rough difference of the barometer and sympiesometer is given, which, for the first five days of each month, is corrected in the final column for tempe- rature,—a correction which may readily be applied to any of the others. TABLE I. Bar. corrected Att. fortemp. Symp. Att. 1829. Barom. __ Ther. a. b. Ther. a—db. Oct. 1, 30.045 63.5 29.965 29.916 64.0 0.049 oo) 2, 20.728 64.5 29.644 29.596 65.0 — 0.050 » 8, 29.309 63.4 29.229 29.158 64.1 0.071 . 4, 29.282 640 29.201 29.141 64.4 0.060 5, 29.098 63.2 29.019 28.949 64.4 0.070 Mean. 0.060 Nov. 1, 29.799 58.6 99.731 29.683 59.8 — 0.048 2, 29.806 59.8 29.734 29.679 61.0 0.055 6, 29.232 59.6 29.163 29.092 60.7. 0.071 7, 29.483 58.7 29.415 29.339 59.7. 0.076 8, 29.576 57.6 29.511 29.481 59.3 0.030 Mean 0.056 Dec. 5, 29.806 61.0 29.732 29.663 622 0.069 6, 29.987 59.2 29.917 29.820 60.4 © 0.087 9, 29.987 58.3 29.920 29.825 60.0 — 0.095 10, 29.728 56.7 29.665 29.595 58.7. 0.070 11, 29.350 53.8 29.294 29.251 55.4 — 0.063 1830. Mean 0.077 Jan. 1, 30.401 53.6 30.345 30.271 548 0.074 2, 30.315 53.5 30.259 30.172 547 0.087 $, 30.194 54.7. 30.186 30.052 55.5 0.084 5, 30.016 55.2 29.957 29.865 56.3 0.092 6, 29.558 57.0 29.495 29409 58.4 0.086 Aig Mean 0.085 Feb. 3, 29.930 50.0 29.884 29.813 51.3. 0.071 4, 29.704 50.0 29.658 29.612 52.0 0.046 5, 29.505 50.7 29.457 29.392 51.7. 0.065 6, 29.164 50.6 29.117 29.058 52.4 0.059 7, 28.750 53.0 28.698 28.638 54.5 — 0.060 Mean 0.060 Mr Forbes on Barometric Instruments 100 Barr. corrected Att. , fortemp. Symp. Atta t 1830. Barom. ‘Ther. a. b. Ther. a—b. Mar. 2, 29.955 642 29.972 29:743 65.3 0.129 ay 90.667 62.7 = 29.589 29.478 62.8 0.111 5, 29.719 61.5 29.644 20.520 62.7. 0.124 6, 29.803 - 59.2 29.733 29.688 60.9 0.095 7, 29.761 60.2 29.689 9.610 61.3 0.079 Mean 0.107 TABLE II. a8 Att. Att. a—) Barom. ther. Symp. _ ther. corrected 1330, a. t. “De a—b. fore. Apr. 1,° 29.688 . 58.7 29.462 58:7 . .171 0.103 2, 29.475 55.2 29.3816 56.0 .159 0.101 | yy, 3, 29.466 55.0 29.306 55.8 .160 0.10240 °°" 4, 29.752 55.0 29.604. 57.0. 148 0.090 | 220° 5, 29.426 55.8 29.264 56.8 .162 0.102 6, 29.312 59.6 29.100 60.2 .212 7, 29.314 60.8 29.087 62.0 .227 8, 29166 61.7 28.915. 62.5 .251 9, 29.001 63.0 28.800 63.3 .201 10, 29.081 62.6 28.880 63.6 .201 11, 29.143 62.2 28.878 62.7 .265 12, 29.050 62.7 28.786 64.3 .264 13, 29.516 62.3 29.263 63.2 .253 14, 29.464 63.0 29.220 63.6 .244 15, 29.325 62.8 29.068 64.1 | .257 16, 29.151 65.5 28.845 65.5 .306 17, .29.009 62.7 28.728. 63.0 .281 18, 29.313 622 29,062 63.6 ..251 19, 29.164 60.6 28.941 62.0 .223 20, 29.412 60.6 29.170 61.3 .242 May..5, 29.782 64.2 29.501 64.3 .281 0.200 .6,..29.570 . 65.4 29.296. 65.3. .274 0.190 | ay 7, 29.340 62.0 29117 64.2 223 0.147 ba ten 8 29.362 59.6 29.095. 60.2 .257 0.187 | 217? 9, 29.390 55.4 29-195 56.2 .195 0.136) 10, 29.564 58.8 29.366 58.8 .198 Us 11, 29.604 59.0 29.390 59.5 .214 12, 29.626 58.2 29.427 58.4 .199 13, 29.794 58.8 29.574 59.4 .2206 14, 29.762 60.8 29.533 60.2 .229 15, 29.756 60.4 29.536 60.5 .220 16, 29.799 60.8. 29.560 60.9. .239 17, 29.683 62.7. 29.436 62.4 . 247 18, 29.447 63.6 29.171 63.1 .276 May 19, 29. 549 acting by compression 61.8 60.6 59.2 54.7 —- 9.6 59.8 60.5 60.6 59.4 61.6 61.2 64.0 63.0 60.5 — 65.6 60.7 62.0 61.7 61.2 63.6 61.8 62.0 62.0 64.2 62.2 62.2 62.6 60.6 61.2 63.6 29.295 29.425 29.407 29.425 29.412 29.182 28.770 28.659 28.987 29.386 29.221 28.920 28.877 29.270 29.417 29.184 29.112 29.365 29.276 29.393 29.666 29.735 29.383 29.152 29.016 28.930 29.072 29.217 29.402 29.293 28.914 28.895 29.002 29.005 29.633 29.242 29.310 29.263 29.067 29.150 29.016 29.165 29.397 29.279 28.990 28.994. 29.210 29.357 29.0380 61.9 60.7 59:3. 0.183 0.197 0.181 0.193 0.195 0.206 0,238 0.233 0.214 0.212 101 Mean, 0.190 0.22) 102 Mr Forbes on Barometric Instruments Barom. ‘ a. July 7, 29.163 8, 29.012 9, 29.090 10, 29.412 11, 29.411 12, 29.290 13, 29.687 14, 29.455 15, 29.356 16, 29.391 17, 29.315 18, 29.253 19, 29.534 20, 29.859 21, 29.748 22, 29.013 23, 29.589 24, 29.685 25, 29.784 26, 29.880 27, 30.050 28, 30.108 29, 29.893 30, 29.591 31, 29.633 Aug. 1, 29.325 2, 29.164 3, 29.488 4, 29.590 5, 29.495 7, 29.491 8, 29.479 20, 29.701 21, 29.687 22, 29.633 23, 29.462 24, 29.352 25, 29.226 26, 29.406 27, 29.314 28, 29.167 29, 29.567 Att. ther. Cc. 64.0 62.4 63.6 63.2 64.0 63.6 63.2 62.8 65.2 64.5 61.3 63.7 64.5 64.8 66.1 67.0 68.0 67.7 70.0 71.5 72.5 75.0 70.7 71.6 69.7 67.7 69.0 67.2 65.6 66.5 65.0 65.4 62.4 63.0 62.7 63.5 63.7. iy Oy ANS 62.7 63.5 60.7 64.0 _ Symp. b 28.840 28.700 28.776 29.122 29.106 28.985 29.391 29.170 29.040 29.084 29.022 28.940 29.239 29.250 29.429 29.287 29.242 29.327 29.428 29.464 29.634 29.660 29.506 29.154 29.240 28.950 28.742 29.130 29.253 29.167 29.158 29.151 29.404 29.391 29.340 29.145 29.041 28.906 - 29.101 29,008 28.884 29.277 ra Att. ther. 64.1. 62.3 64.3 63:3 64.2 64.0 63.5 63.1. 65.1 64.5 64.8 64.3 64.5 64.7 65.8 67.6 67.9 67.9 69.5 70.6 72.1 74.8 70.6 71.4 69.3 67.6 67.7 67-0 65.7 66.0 65.0 65.7 62.8 63.4 . 62.8 63.9 63.9 63.0 63.2 64.0 61.1 64.0 .293 317 311 .320 .305 .306 283 290 0.286 0.330 0.270 0.253 0.241 Mean, 0.276 In these tables an unequivocal and very considerable fall in the indication of the sympiesometer is evident.. The difference oo acting by compression. _— 103 of the index errors are by no means uniform, and, even in a few instances, have a negative instead of a positive sign. These, however, are not real exceptions, for the negative re- sults are quite trifling, and very far below the amount of the second differences. 'The irregularities are obviously not from errors of observation, since they have a connection from day to day with periods of maxima and minima; and the attentive reader will probably have already observed the important influence of the contemporaneous circumstances recorded in the other columns of the table upon the column of differences. The discussion of these more intricate effects we postpone to another part of this memoir ; but no theory of these variations of second differences can prevent our concluding, that the level of the sympiesometer was gradually sinking. This phenome- non will not, I imagine, be observed in stationary instruments. Iam disposed to attribute it to the gradual transmission of minute globules of air shaken into the oil in the cistern, by frequent carriage, upwards through the column which confines the hydrogen gas. It must, however, have been a gradual process, and was attributable to no carelessness in use. ‘To ‘my full belief, the sympiesometer, while in my possession, was never turned upside down even for a moment ; and, in all my perambulations, the column of oil was never once separated. § 3. Onan Error of Variable Magnitude depending on ea- - ternal circumstances. This most important and most troublesome of the errors af- pei the sympiesometer, arises from the want of strict ac- cordance in the indications of the mercurial and gaseous bulbs at the same instant, as regards temperature. We have seen from the theory of the instrument that its whole accuracy depends on the postulate, that the effects of heat on the gaseous bulb shall be accurately eliminated by the precise correspond- ence of the indications of the mercurial thermometer. The ut- most delicacy is here requisite. The error of.a single tenth of a degree of Fahrenheit will create an error of nearly a fathom of altitude in the scale of heights, (at thirty inches of pressure ;) -and those who are accustomed to delicate thermometric expe- -riments must be aware how often, even under favourable cir- ~ 104 Mr Forbes on Barometric Instruments cumstances, that error must be increased four and five, nay, ten times. 'The very dissimilar sensibility of the bulbs, the one containing the rarest known substance, the other the densest of fluids, involves sufficient sources of error. But in the sympiesometer these bulbs have been placed at such a distance from one another, and under such different circumstances, that, unless under the most favourable conditions, the coincidence is but a happy compensation of errors. Before my first paper was published, I had theoretically examined the sensibility of the bulbs, and ‘found the difference perfectly erroneous; it is, however, modified in practice by the inclosure of the gaseous bulb in the brass cylinder, and the free exposure’ of the mer- curial one, which, if im some cases it equalizes errors, frequently gives rise to very troublesome ones. The errors from this source to which the sympiesometer is exposed, are therefore of two kinds, the one arising from the different temperature of two contiguous strata of air in which the two bulbs are placed ; the other from rapid changes of temperature which affect one bulb more speedily than the other. The first of these, trivial as it may appear, is frequently of serious inconvenience, par- ticularly in observations within doors, where the draught of _air from a door or window may prevent the instrument from acting for half an hour after the cause of inequality has been removed. Even the distance of fifteen inches between the bulbs is often sufficient, in a perfectly still room, to impart a sensible difference of temperature to the two. ‘The unequal sensibility of the bulbs being, as I endeavoured in my former paper to demonstrate, the great defect of the in- strument, particularly when used in the open air and applied to the measurment of heights, I resolved to institute experi- ments on the time required. by each respectively, to acquire a new temperature in’ perfectly still air. The obvious mode of experiment was to bring the instrument into a medium. differ- ing in temperature by a considerable number of degrees from. that in which it had already acquired an equilibrium, and then converting the gaseous column intoa simple air thermometer, by eliminating the effects of pressure, compare the accessions of heat indicated by the two thermometers at different intervals of time. The conduct of the experiment, however, required _ acting by compression. 105. much delicacy, and some contrivance ; but I succeeded in re- peating it several times with a degree of precision beyond my expectation. The most convenient time was in frosty weather, when the external air differed considerably in temperature from that of the room in which they were made. | But the difficulty was, how to observe the indications of these delicate thermo- meters, without approaching to them the warmth of my body. For this object, I availed myself of the elegant principle first noticed by Gauss and applied by Captain Kater to his floating collimator, which enables us to view an object at a short dis- tance witha telescope, by means of the intervention of a second object-glass, in the focus of which the object to be viewed is placed ; and since, on passing through ‘the detached object-glass, the rays of course emerge parallel-to each other, in that state they enter the object-glass of the telescope. I employed a fine forty-two inch achromatic with a considerable power, and ad- justed to the farther extremity of it a pasteboard tube, con- taining an object-glass of about four feet focus, at which dis- tance beyond, the sympiesometer was hung for observation. By this means I was sitting at the eye end of the achromatic, about nine feet from the instrument, recording its motions with the same precision as if I had been within six inches of it. These observations will not only prove valuable as a correct indication of the relative sensibility of the bulbs, but will form the most precise illustration of the laborious length of time required in still air to induce an equilibrium; so that where the instrument is wished to act on a sudden transposition to air of a different temperature, unless it. be exposed to wind, it must often be wholly useless. The following series was made by exposing the instrument outside of a window on a calm day, when, by the final result, the external temperature appears to have been 36°.0. At the time of exposure the temperature sliown by both bulbs was 53°.2. The pressure continued sta~ tionary. “106 Mr Forbes on Barometric Instruments TABLE III.—28th December 1829. : Sek from © Thermometers. Excess above surrounding ait- — e com- mencement. Gas. . Mere. Gas-. - Mere. Diff. — hy §3°.2 53°.2 17°.2 17°.2 0°.0 0.30 52.6- 51.3 16 6 15.3 —1 3 1. .0 51 8 50 «1 15 8 14.1 —1.5 1.30 51.3 AQ .2 15.3 13.2 —2.1 2..,0 50 .3 48° .2 14 .3 12 2 —2.1 2.30. 49.4 -47.4 (18.4. 114. 29800 3.0 48 .6 46.9° 12.6 10 .9 —1.7 3 .30 ANT .4 46 .1 11 .4 10.1 —1.3° 4. 0 46.8 45.8 10 .8 98 —1.0° 4. 30 AG .1 45 .3 10.1 9.3 —0.8 5.1 Dido bath sd4iok 91.0: io Qudabangi@aile 5 .30 Ad 1 44 7 Soh vins ofted +0 6 6.0 43 5 44 .2 7 5 8.2 + 0.7. 6 .30 43 .1 43 8 ae | 78 OOF TEO 42.7 43 .4 6.7 C0 eed 7.30 42 .4 42 .7 6 .4 6.7 POS 8.0 41 .4 42 .4 5 4 6 .4 +1.0 8 .30 41 .4 42.1 5.4 6.1 + 0.7 9.0 40 .6 41 9 4 6 59 $A 3 9 .30 40 .2 41 6 4.2 5 .6 +1.4 10.0 , 39.7 AIS 3.7 DS cy oad 10 .30 39 .5 Al. 3.5 5.1 + 1.6 11. 0 39 .1 40 .9 3.1 4.9 +718 11 .30 38 .7 40 .6 2:7 4 6 +19 12.400; 38.5. 40.4 2.5 4 4 +1.9 12.30 _ . 38.2 40 .2 2.2 4.2 + 2.0 13. 0 38 .0 40 .0 2.0 4.0 + 2.0 13 .30 37 8 39 .8 1.8 3.8 +2.0 14. 00: BEC ee OT eg oe 14.30 37.5 39 .4 1.5 3 .4 +1.9 15) 0° 8716.» oggig4° Mg Bisa 15 .30 37 .2 39.1 1.2 3.1 +19 16. 0 37 «1 39..0. $23 3.0 + 1.9 16 .30 37 1 38 .8 1.1 28 +.1.7 17. 0 36 .8 38 5 0.8 2.5 Tei bode 17 .30 36 .6 38 .4 0 .6 2 .4 + Le 18. 0 36 .6 38 .3 0 .6 2.3 + 1.7 18 .30 36 .5 38 .2 0.5 2 2 +1.7 19.0 36 .4 S81 ., 0 .4 2.1 opi 19 .30 36 .4 38 .0 0 .4 2.0 +1.6 20. 0 36 .4 38 .0 0 .4 eu + 1.6 acting by compression. 107 20.30 8836 3/0 37 9 0.3 ‘Ss £16 2.0. 863. ,.37.8 0.3 18 25 2130 363 37.6 0.3 1:6. "dea 22. 0 36:8 37:5 0.3 wee 22:30. 36:2 3754 0.2 lia pie 22.0 36:2 S74 0.2 14 +12 23.30 6:1 3752 | 12 +111 24. 0 36.1 $7.2 0.1 be 3 +321 24.30 36.0 37.1 0.0 ial oe 25.0 36:0 37:0 0.0 BD. #10 25 .30 36.0 87.0 0.0 BO. #140 26. 0 36:0 36,9 0.0 09 +4029 26 .30 36:0 36.9 0.0 09 +£0.9 27. 0 36.0 36.8 0.0 08 =+40.9 27 .30 36.0 36.8 0.0 8 2 009 In the preceding table there is a circumstance worthy of particular notice. I allude to the apparently greater sensibi- lity of the mercurial bulb at the commencement of the obser- vations, as indicated by, the sign of the column of differences. We there observe a minimum at 2’, a change of sign, or coinci- dence, at 5’, a maximum at 13’, and a third coincidence would soon have taken place had the observations been extended be- yond 28’. Now this arises from the observations not ‘being made in still air, (for though calm, the instrument being out- side of a window, was exposed to currents,) which, acting on the freely exposed mercurial bulb, did not reach so soon the gas, which is sheltered by a brass cylinder. It is to this peculiar mode of affection that some singular motions of the two thermometers are to be ascribed which perpetually occur in external observations, and occasionally producing ad- ventitious coincidences the indications again diverge. In the two following series we have almost strictly the result of the action in still air being made in a room after exposure to the external cold. Had we it in view accurately to analyze the rate of heating, we should have to apply some minute correc- tions for the change of pressure during the experiment, and for the deviations from perfect equality of temperature of the bulbs at the commencement. But they are amply accurate for our present purpose. Mr Forbes on Barometric Instruments 108 TABLE IV.~—28th December 1829. SE AOSSSRARGM IHD HDR NAANK ANNA MM nN SCSoOoSSOSCOSoCKS BO LDL HPP HTH FTE TTP SHE Pte eet HHH te tet S = : 5 BOAR ARAQLAMYGOSCHSPOMNRSH HAN VAISCHMUNSSRYHAHSHDrLOON Eg PRA EASI VIN | QAR IACHHAVSCOHVANQADSHroon B BALL II AL SSOMr Ke oomw wea OOM NR R WM socscs 5 & gTPOROSOM ANOS HQAQAIMHASHNOTAINSCRRNOCOMHENAREIH Q OG SFBISHSHOOWHAANAINIONRNNNGH rH OSSOSCOOCSoSOCOCCSCS » ERRAND QAQLOCTADAANOAQVOANAGHASHHOMOHAMHTORDOOR 3 Bo * * . . » aD wha @e el! @ ve Oy A i oe ee wn eS S SSrTRORSOSCHARHMHHHIODDOOOREDR S S SRHGRSISIISIVAISSIISS SET TLLAVFSSLSSSRRSSSSSSS E A gS RGttTS gr DoaggnonregnrsqonqoqrnwQongnqgacnanans A S5nroaneox (© ir DOARAARSSOSSSSOSSS [Sm ee CRAM HHAHaaS THERMO RSRSSISSSESSSSSSCSS aaereaer Sgescssooooosoessoosossosoessoecoscooossosscoscososc(o mencement, Times from the com- acting by compression. 109 40. 0 51.3 50.9 0.1 0.5 + 0.4 41. 0 51.3 51.0 0.1 0 .4 +0.3 42. 0 51.3 51.0 0.1 0.4 +.0.3 0 51.2 651.1 0.2 0.3 +02 hs 0 51.2 51.1 0.2 0.3 +0.2 5. 0 51.3 51.2 0.1 0.2 4+ 0.1 46. 0 51.3 51.2 0.1 0.2 +01 47.0 51.4 51.2 0.0 0 .2 +02 48. 0 51.4 51.2 0.0 0.2 + 0.2 49. 0 51.4 51.3 0.0 0.1 + 0.1 50. 0 51.4 51.8 0.0 0.1 + 0.1 In the preceding table the thermometers set out from a somewhat different temperature, which is the cause of the — sign in the column of differences, as is also the case in the fol- lowing ; but the moment of coincidence may easily be found, from which, if required, the times may be reckoned. In both it is nearly at the first minute. TABLE V.—2d January 1830, Times from Thermometer. Defect below surrounding air. ° une Gas. Merc. Gas.’ Merc. Diff. 0.0’ 33.0 358 21°92 184 — 28 au er), SE.8 37 .8 17 .0 16 .4 — 0.6 oe. 906 38.5. 14.6. 1bst- +48 3.0 41 .6 39 .5 12 .6 14.7 + 2.1 4.0 43.2 40 .5 11 .0 13, .7 +24 5.0 44 .4 41 .4 9 8 12,84: +30 6.0 45 .6 42 .3 8 .6 11.9 +3.3 "0 46.4 43.1 1601 be 4 oe 8.0 47.0 43 .8 q 2 10 .4 +32 Se 46944.) 86.40) 9On ee 10.0 48 .3 45.2 5.9 9.0 + 3.1 me... 489 “460° 68 SS BB Bg eo 8 8G 9. 8h BON Si 13.0 49 .7 47 0 4 5 7 2 + 2.47 140° 500 (47.5 42° 6a 4 O'5 15.0 50 .3 48.0 § 3.9 6 .2 + 2 3° 16.0 50 .6 48 .4 3 6 5 8 +22 17.0 50 .9 48 .8 3 13 5 A + 2.1 18.0 51 .0 49 .2 3.2 5.0 + 1.8 19.0 51 3 49 .5 2.9 4.7 +1.8 20 .0 51 .4 49 8 28 AA +1.6 - \ 110 Mr Forbes on Barometric Instruments i from Thermometer. Defect below surrounding air. ~ e com- . mencement. Gas. Mere. Gas. Mere. pies” ovo” 56 SO | 6G S OES Om 22 .0 51..7- 50 .3 2.5 3.9 he 1.4, 23 .0 51.8 50:6 2 4 3.6 ha 24.0 51 .9 50 .8 2.3 B.A ise eS aq 25.0 52.0 51 :2 2% 3 .0 + 0.8 26.0 52.2 51.3 2.0 2.9 + 0.9 my, oS Ge Te ae oh 28 .0 52 4 51.8 1:8 2 4 + 0.6 29.0 Se «$19 roa 2.3 + 0.6 30.0 52 .7 52 .1 1.5: 2 1 a 0.6 31.0 52.8 §2:.3 1 4 1.9 E 0.5 82.20 io sebROes al Bisher ow AaSjuor AcQiRih awobnos 93.05 ci scBBoO) cali th cocci 'é deuBlos ole alae 34.0 53.1 52 .7 1.1 ae +. 0.4 35 .0 1S ee 1.0 14 40.4 36 .0 53 .2 53 .0 1.0 1.2 bs a 37 .0 53 3 53 .1 0 9 ra os * 38 .0 53 4 53 2 0.8 10 ~ £92 39 .0 53 5 53 .2 0.7 1.0 +23 ° - 40.0 53 .6 53 4 0 .6 0.8 + 0.2- 41.0 53 .6 53 .4 0 .6 0.8 + 0.2 42 .0 53 .7 53 .6 0.5 0 .6 +01 43 .0 53 .'7 53 .6 0.5 0 6 +0.1 44.0 53 .8 53:7 0 .4 0.5 + 0.1 45 .0 53 .8 53 .8 0 .4 0 .4 +0.0 46 .0 53 .9 53 9 0.3 0.3 w 4A'7 .O 53 .9 54 .0 0.3 0 .2 48 .0 58 9 54 .0 0.3 0 .2 49 .0 54 .0 54.0 0.2 0.2 50.0 54 0 54.1 0 .2 0.1 51.0 54 11 54 .1 0.1 0.1 52.0 54.1 54 .2 0.1 0.0 53 .0 54 .2 54 .2 0 :0 0.0 These tables may hereafter be referred to for numerical de- ductions; but, in the meantime, we may draw the following: 1. That a coincidence of temperature in the bulbs may be either accidental or permanent, as illustrated in the first of these tables: 2. That the accidental coincidence can never be calcu- lated upon, and, therefore, in the present state of the sympie- someter, we must wait till both bulbs have acquired the tem- perature of the air. 3. That in still air, setting out from an acting by compression. ‘Ni lll; excess or defect of 15°, about 50/ must be given to acquire the equilibrium, for 10° about 44’, for 5° about 34’. These last two coincidences strikingly agree in both the last tables. seems the proper place to give an additional and direct eS (though I think that those who carefully read my last paper will hardly require one,) that the observations upon which I built my opinion of this being the main defect of the instrument, giving in a former number of this Journal, were not affected,—at least in their great and rapid variations, by the barometric difficulties of the place, arising from the con- finement of a large mass of air in a deep ravine, of which the temperature and density might be liable to considerable varia- tion. The following observations contain a comparison of the sympiesometer with a portable barometer with adjustable level, &c. and prove both the existence of the oscillations which I described, and, being made with every precaution to avoid the influence of radiation, that they are owing to the unequal sensibility of the bulbs, as, from the analysis of about 100 observations near the same spot, I endeavoured to de- TABLE VI.—May 18, 1829. Att. Det. Att. _ Station, Hour. | Barom. Ther, Ther. Symp Tner, Colinton House, 12°.25 29.558 62.5 60.5 29, 48 62.1 Water of Leith, 12 .40 29.47 63.2 12.45 29.724 ‘70. 29.645 63.2 12 .50 29.720 68. 29.69: 62.4 12 .55 29.715 62.7 Bb of 63. 1.5 29.724 66... 64. 29.715. 64.0 1.10 63... 29.745. 63.8 1,15 63. 29.725 63.2 1.20 29.716 65. 63. 29.695 63.2 1 .25 64. 29.705 63.8 Colinton House, 1.40 29.562 74. 29.415 63.8 1 45 29.49 67.8 1.50 29.550 71. 29.505. 67.9 1 .55 29.52... 68.1 2.0 29.554 70. 29.525 68.1 2 6 29.535 68.3 2.25 29.553 69. 29.51 67.8 112 Mr Forbes on Barometric Instruments TABLE VII. ~~May 15, 1829. 93 ’ Att. Det. Att. Station. Hour. Barom. Ther. Ther. Symp. Ther. Colinton House, 2°.35 29.647 62. 59. 92958 61.6 Water of Leith," 3° '0 29.58* 60.1 3.5 29.788 64. 57. 29665 583 3.10 ett 29.745 58.4 3.15 57.5 29.755 58.6 3.20, 29.791 60. .. 29.77. 58.2 3.25 55.7 29. cre 57.6 3.30 29.788 58. 56.7 29.78 57.6 3 .35 56.7 29.78 57.6 3 .40 58.5 29.81 + 58.4 3.45 29.790 58. 58. 29.77 58.6 Colinton House, 4.5 29.660 59. 58: 29.475 60.8 iy 4n25 ; 29.56. 62.5 4 .30 29.59. 63.2 The detached thermometer used at the Water of Leith was a delicate pocket one. As in hot and calm weather the errors from intiegaead sensi- bility of the bulbs are greatest, so are also the errors of the first class which include the varied and complex effects of ra- diation and reflected heat. The dissimilar situation of the bulbs render a coincidence in bright sultry weather very diffi- cult: the mercurial thermometer being much nearer the ground, and unprotected by any exterior casing, is often more affected by reflected heat than the more sensible gaseous column, so much so, that in extreme cases of reflection, I have sometimes closed the brass case of the instrument to place both bulbs more nearly in the same condition. ‘The action of the sym- piesometer when used abroad is therefore very dependent up- on external circumstances, and the precautions of observation, and the number of times they require to be repeated, must of course vary according to these. Cloudy and windy weather is most favourable for promoting an equilibrium, which unfor- tunately is not the most conducive to the accuracy of the great conditions of barometric measurement. Under opposite cir- cumstances, and particularly in confined situations, the aecu- rate determination of the true indications of the instrument becomes both. uncertain and harassing, and should it be thought a trifling objection that half-an-hour’s assiduous ob- * Cistern 3’ opened. + Gleam of sunshine. acting by compression. 118 servation is frequently requisite form even an approxima- tion, I would remark, that, of all requisites for the consider- able extension of approximate barometric measurements, and for the adoption of an instriinent as a constant travelling com- , one of thé very most important is promptness of action: en he is not alone, the inconvenience will be severely felt by the observer, and even if his motions are.at his own com- mand, it is impossible, in a journey of any extent, to make fre- ‘quent halts, unless the duration of these be moderately short, and little liable to fluctuation. From absolute want of time, I have frequently been obliged to leave series of observations unfinished when the equilibrium was longer of being obtained than I anticipated. It is proposed in the Second Part of this Memoir to enter upon the general applicability of manometric instruments to the measurement of heights, illustrated by the results of a great number of observations ; but I think that the effect of accidental external circumstances, and the time required» for bringing the sympiesometer imto correct action, will be most satisfactorily shown by the details of obsservaions made at a variety of seasons for the determination of the height of a par- ticular station. For this purpose, I shall select a pretty ex- tensive series, made upon the difference of level. of Colinton House, and the dam of the lower Bonally Reservoir, a station, which, though not so favourably placed as an insulated peak, is yet freely exposed, and “directly commanded on few points of the horizon. This is not the place to enter into particulars respecting the mode of deducing the heights, and to trace their errors, but I shall premise that the only correction applied to the approximate height derived from the differences on the logarithmic or fathom scale of the instrument, was that ‘for the temperature of the air, the expansion of which, at the sup- posed average state of moisture, was taken at .00250 for each degree of Fahrenheit above 32°; a number of reniarkably easy application, and, as I shall afterwards show, not differ. ing more from that more usually adopted, than the same quan- tity, as proposed by different philosophers of equal eminence. In the reductions of my measurements of heights, I have al- most always made use of the variations of pressure during the NEW SERIES, VOL. Iv. No. I. JAN. 183]. H 114 Mr Forbes on Barometric Instruments intervals of observation at the lowest station, determined by a standard » barometer, which, gives these observations - every advantage ; for one of the greatest defects of the sympiesometer is the uncertainty attending its indications of minute horary changes, and the long time which, after returning to the lower station, (if within doors) we must wait for a corr espond- ing observation. 'The observations with the barometer on which, in conjunction with those of the sympiesometer, the small changes of pressure were determined, are not detailed, as irrelevant to the present object. | '.. Experiment 1.—May 20th, 1829. Fine. Wind E,, brisk. Symp. Att. Det. Hour. Inch. Fath. Ther. Ther. Colinton House, 12.520’ 129.815 — 169 62.8 59 Bonally Pond, cistern of symp. 5’ open, 4.15 29.13 = 270 56.2 4.20 29.085 = 276 53.9 58% 4.25 29.085 = 276 54.2 531° — 4.30 29.085 = 276 542 531 Colinton House cistern ' ae : 10’ open, 5.45 29.735 —181 640 533. 5.55 29.80 =171 63.0 ; 6.30. 29.835 = 166 62.2 Deduced height, 671 feet, or 1086 above the mean level of the sea. Remark.—The uncommon excellence of this day’s observa- tions, the instrument having become quite stationary in about 10’, is owing to the combimation of circumstances most favour- able of any to the action of the sympiesometer, viz. a brisk wind blowing from a point nearly opposite the sun. The de-- tached thermometer on the hill was a delicate pocket one by Cary. ExPERIMENT 2.—May 26th, 1829. Very fine day. Wind S.E. moderate. Colinton House, 12° 0’ 30.21=112 62.4 57.5 acting by compression. 115 a Ds 5 open, 1.25 29. 46 mn 221 §3.5 1 30 29. 44 = 224 528 1.35 29. 43 — 226 53.2 1.40 29.4385 = 225 53.5 Colitton ¥ House, 6.45 30.145 — 122 Dedsioed one be 696 feet. Above the sea, 1111 feet. Experiment 3.—May 30th, 1829. Fine. Wind N. E.° Variable force.- Colinton House, 10.555 «629. 89 — 1585 65.4. 64 Bonally Pond, 5‘open, 12.10 29.255=251 60.1 « (calm) 12.15 29.235 = 254. 58.2. 56 (breeze) 12.20 29. 32 = 242 , 57.6 55: 12:25 29. 22—256° 556 54> 12.30 29. 20—260 55.0. 54.5 12.35 29:19 — 261 9 55.8 55. 12.40 29. 20— 259 55.5 54 Noe oe House, 8.15 29. 84=166 63.8. 62 4. 0 29.835 167 63.8 | Dedueed height, 634 feet. Above the sea, 1049 feet. sa Seidne difficulty, as to the variation of pressure in the interval, owing to different indications of the sympiesometer and barometer, probably partly occasioned this small result, compared with the last. Experiment 4.—July 6th, 1829. Wind W..; brisk. Colinton House, 2.25 0 29.320 — 241 67.2 : 65 Bonally Pond, 5/ open, 3.10 28.575 = 352.5 57.8 58 $.15 28. 58= 352 57.6 58 Colinton isis. 5.40 29. 27—249 648 62 Deduced height, 698 feet. Above the sea, 1113 feet. Remark.—The extraordinary facility of these observations was entirely owing to the brisk wind.. If I recollect right, the day was also cloudy. The instrument, it would appear, had acquired very nearly the temperature of the air in the first five minutes. 116 Mr Forbes on Barometric Instruments Exreriment 5.—December 31st, 1829. Cloudy ; wind E.; snow deep on the ground. Symp. Att. Det. Hour. Inch. Fath. Ther. Ther. Colinton House, 2.520° 30.30= 99 57.1. 35 Bonally Pond, 2 open, 3.17 29.50 = 214 30.7 3.25 29.51=213 30.4 Colinton House40’open 5.20 30.28—102 544 84 5.45 30.28= 102 54.9 - Deduced height, 679 feet. Above the sea, 1094 feet. Remark.—Here we have the measurement under very diffe- rent circumstances. A change of temperature from 58° to 30°, and deep snow on the ground. In noting this series, I have remarked, “I am conviticed, that, however personally inconve- nient, such weather is best for the measurement of heights, es- pecially with the sympiesometer.” Indeed, nothing can be so favourable for promoting an equilibrium of temperatnre as a covering of snow, combined with the small radiating effect of the sun at low altitudes. This, accordingly, is one of the most accurate, as well as shortest, series of this collection. ExrEeriment 6.—January Ist, 1830. Colinton House, 2.220’ 80.275 = 102.5 55.2 32 Bonally Pond, 5’ open, (observation a little deranged,) - 8.45 29.52 = 212 25.6 3.50 2950/= 215 25.5 Colinton House, 5.20 30.17 =117 52.5 7.30 30.21 =112 555 30 Deduced height, 642 feet. Above the sea, 1057 feet. Fixprkiment 7.—January 9th, 1830. Colinton House, 2.50 29.53 — 210 57.6 42 Bonally Pond, 20’ open, 3.55 28.89 — 306. 35.6 Colinton House, 5.40 29.58 — 203 59.1 38: Deduced height, 618 feet. Above the sea; 1038 feet. Remark.—This day’s observation affords an example of one of the casualties attending the use of the sympiesometer. ‘The } ; ; : ——eSe—_ acting by compression. 117 _ observation at 2" 50’ within the walls of a room was found to be deranged by the accident of the window being open, and, had not the barometer been employed for the estimation of the horary variation of pressure and computation of the height, along period must have been wasted on permitting the in- strument to attain an equilibrium in the room. Experiment 8,—Jannary 23d, 1830. Wind E.; brisk. Colinton House, 2.525’ 29.635 —196 51.5 35 Bonally Pond, 5’ open, 3.40 28.90 = 304 30.4 Colinton House, 5.35 29.60 =200 56.0 : 8. 29.58 — 202 657.5 Deduced height, 639 feet. Above the sea, 1054 feet. Remark.—The circumstances of little radiation and a brisk wind blowing opposite the sun at a temperature of 2° below the freezing point, rendered this series very readily observed. _ Exprrtment 9.—February 12th, 1830. Colinton House, 2.5 0 29.49 = 217.5 59.0 46 Bonally Pond, 15’ open, 3. 30 28.78 = 322 38.8 3 35 28.78 = 322 38.9 Colinton House, 6.15 29.47 — 220 61.1 Deduced height, 645 feet. Above the sea, 1060 feet ExPrErimMent 10.—March 13th, 1830. Colinton House, 2.510° 29.50 — 214 63.8 48 Bonally Pond, 10’ open, 3.15 28.82 =S16 41.6 Colinton House, 5.30 29.46 — 221 59.4 7.15 29.455 = 222 58.7 Dedwced height, 618 feet. Above the sea, 1033 feet. _ Experiment 11.—April 17th, 1830. Wind S. W. with violent gusts and stormy showers. Colinton House, 12.% 5 28.64 — 344 643 55 Bonally Pond, about 10’ open, 1.15 28.06 = 433 47.2 Colinton House, 4.15 28.72 — 331 61.0 55 Deduced height, 581 feet. Above the sea, 996 feet. 118 Mr Forbes on Barometric Instruments ©) Remark.—This observation gives a result differing more from the mean than any of the others of this series. This arises from ‘the stormy state of'the weather, so inimical to barometric obser- vations of all/kinds,—not from the defects of the instrument. It -must be observed of this and some preceding experiments, that there is not more ‘than !one observation’ at the higher station. This arose from the accidental circumstance of my being able to leave the sympiesometer 10’ or even 15’ to take the temperature of the air, which was abundantly sufficient for the purpose in moderately windy weather, when the direct heat of the sun, and its reflection were null or trifling, as in one ‘weather during) the winter season, Exreriment 12.—June 5th, 1830. Symp. Att. Det. Hour. Inch. Fath. Ther. Ther. chaton House, 1€" 0’ 29.875 = 233 62.6 59 Bonally Pond, 10’open. 415 28. 66 = 340 52.8 4.20 28. 66 = 340 528 « Colinton House,, 8.30 29. 36 = 236 60.4 56? Deduced height, 675 feet. Above the sea, 1090 feet. ExrreriMEnt 13.—June 26th, 1830. Colinton House, 2° 45’ 29.02 = 285.5 64,1 62 Bonally Pond, 10’ open, - 3.50 28.30 = 395.5 61.4 Sunshine. 4. 0 - 28.34 = 390.5 62.0 Do. 4, 5 . 28.30 = 395.5 61.4 Do. 4.10. 28.345— 389 60.4 breeze&shade. Colinton House, 8. 0 29.08 = 277 64.8 Deduced height, 676 feet. Above the sea, 1091 feet. Remark.—These observations afford an instructive example of a source of error to be guarded against, perhaps two days in three of observations in summer. Although carefully shel- tered from direct ‘sunshine, it was impossible to avoid a degree of reflection from the neighbouring grass : the consequence was, ~ that, as we took the indications after an exposure of 10’ or of 20’, we should have differed 30 feet in altitude; and, by acting by compression. 119 waiting 25’, and finding it again reduced to the indication: at 10’, we might have fancied it correct, and thus be led into an error amounting to 39 feet, which could only be detected by a much longer series of observations, unless a breeze had hap- pily occurred with passing clouds, which, after a stay of half an hour, assisted us in approximating tothe truth. Buta cir- cumstance worthy of remark is this,—that in observations at 3® 50’, 4" 0 and 4° 10’, the indication of the air column of the instrument never changed. The oscillations in the deduced pressure were caused solely by the varying indications of the mercurial thermometer. This was readily explained, for the instrument being itself in perfect shade, the gaseous bulb was, from its position, of course a foot and a-half farther from the reflecting grass than the mercurial one, and, besides, defended from radiation by its polished case of brass; and thus, the mercurial bulb becoming, contrary to its usual state, the more sensitive of the two, occasions errors in sultry weather which, on the present construction of the instrument, are quite inevi- table, Experiment 14.—July 24th, 1830. Quite calm; very warm; close gray clouds generally obscur- | ing the sun; wind generally west. Colinton House, 2° 40’ 29.23 = 239 683 ‘0 Bonally Pond, 10’ open, 3.55 28.67 = 339 67.0 4.0 28.70 = 335 67.2 4.5 28.60 = 350 66.7 a little sun. 48 28.60 = 350 66.8 4.11 28.63 = 346 668 4.14 28.58 = 353 66.6 clouds. 4.17 28.55 = 355 66.9 4.21 28.60 = 350 66.6 4.24 28.62 — 346.5 66.6 4.27 28.70 = 384 65.0 windchanging to / | 4.30 28.62 = 346.5 65.0 N.E.quitecalm. Colinton House, 5.45 29.32 = 241 68.2 69 Deduced height, 678 feet. Above the sea, 1093 feet. Remark.—This series is very instructive. The length of 120° Mr Forbes on Barometric Instruments time, requited’ in ‘observations, and the uncertain natare.of the, result at last.is sufficiently obvious. Even after eleven obser-. vations made at one station, and continued, for the space of three quarters of an hour, we’find perpetual fluctuations, and the 10th and 11th give a difference of indication of no less’ than seventy-five feet in height. The observations were re- peated oftener than usual, and with every precaution to pre- vent derangement, by the approach of the bedy, in order to catch at even a temporary stability; and it is only by an analysis of the causes of fluctuation that we can approx- imate to the’ true indications, When we examine the mo- tion of the gaseous and mercurial columns, we find precisely . similar imdications to those obtained from my experiments in 1825, detailed in my previous paper under analogous circum- stances. ‘The general tendency and ,,,,... POA ils se the temperature was to fall, but this 3°55’ .00in. 0°.0 fall was interrupted by asuccessionof 4.0 43 +0 .2 rises small in extent, owing, perhaps, 4.5 —l0 —85 in part to the succession of clouds 4. 8 0 os | and sunshine, but chiefly, Timagine, 4 .11 +38 0 to the rise of heated strata of air 4.14 —5 —2 from the lower country. The an- 4.17 —3 +.3 nexed table points out most satisfac- 4 .21 +5 —3 torily, by the signs of the successive 4.24 42 0 indications of the gaseous and mer- 4.27 +48 —I.5 curial columns, the nature of the 4.30 —8 0 action. By examining the relations of these two columns, we arrive at this important conclusion, that the motions of the mercurial thermometer always succeed by the interval of about one observation, the indications of the more sen- sitive gaseous bulb considered as a thermometer ; it must be remembered that a rise in the pressure scale indicates a fall of temperature, and the reverse; therefore, opposite signs in the two columns indicate the same ‘effect. ‘Thus, a contrac- tion of the gas at 4° 0’, indicated by +.03, is followed at 4.5 by a fall of the thermometer of —.5; ‘the expansion of the gas —-10 is succeeded by an expansion of mercury of 4-1; a zero in the differences of the one by a zero in those of the other, and so on. In'the conclusion of the series, the sensi- bility of the bulbs seems to have been rendered more uniform acting by. compression, 121 by the change of wind mentioned in the observations, the uni- formity of relation still continuing, but .at. shorter, intervals than. before. This experiment. was performed under an ex- terior temperature, differmmg more than forty degrees from that in Experiment 6. | Experiment 15.—July 29th, 1830. Wind E. Brisk. Very little sun. Colinton House, 1%. 0 29. 55 = 207.5 74.4 68 Bonally Pond, 5’ open, . 2%.10' 29. 01 — 287.5 64.2 2.13 29.00=289 644 2.16 28. 82 — 317 63.0 2.19 28.865 — 309 63.3 2.22 28. 90—303 624 Fog. 2.25 28. 96 = 295 61.6 2.28 28. 96 = 294. 61.6 2.31 28.97 = 292.5 62.8 Clearing. Colinton House, 50’ open, 4.0 29. 54=209 69.3 67 4.30 29. 54=209 70.3 Deduced height, 587 feet. Above the sea, 1002 feet. Remark.—It were easy to enlarge on the peculiar indica- tions of this experiment, but I must simply pot out the real sources of the irregularities which it displays. Here was a brisk wind and no sun, the most favourable protections against errors of radiation.. But the instrument was exposed to air in a high state of moisture, and containing strata of very variable temperature. The gradually approaching fog which had been skirting the neighbouring hills enveloped the instrument with rapid decrease of temperature at 2° 22’, and having attained its minimum, the thermometer began to rise in the last obser- vation as the fog cleared off. ‘The change of temperature dur- ing the decline was sensible every minute, and by the princi- ples shown in the first part of this section, it was obvious that the indications must oscillate; I therefore seized the moment of minimum when the mercury was stationary for three mi- nutes together, and a nearly corresponding steadiness occurring in the gaseous column, it afforded a proof of that being the real pressure, which, without this analysis, could not have been ascertained, and by waiting longer, the occurrence of an oppo- 122 Mr Johnston on a new variety of Mineral Resin. site ‘series of oscillations as the temperature quickly rose, would have involved us in new perplexities. ~ I could have added striking examples of the snfluceldl of fogs on the sympiesometer in higher elevations, but they will be taken up in the Second Part of this Memoir, to which I must also refer all discussion of the fifteen values we have ob- tained for the height of the station before us, and a compari- son with those obtained by geometrical methods. Art. XI.—On a new variety of Mineral Resin. By JamesF. W. Jounston, M.A. &c. &c. Communicated by the Author. Wurtz exploring the refuse heaps of an old lead mine called Settling Stones, about a mile above Newbrough Lodge, the seat of Nicholas Maughan, Esq. and six miles above Hexham, Northumberland, I met with several specimens of a substance having the following properties :-— Colour. Externally, red of various shades, black, and some- times pale yellow, approaching to the colour of amber. Inter- nally, red; or brownish-red, except in the yellow varieties, and by transmitted light of a brilliant deep red colour. It yields to the knife, but is hard, brittle, and hasa bright glassy small conchoidal fracture. The fragments are transparent, and the fractured surfaces exhibit a pale greenish tinge, (an opalescence) which becomes more decided after the lapse of.a few weeks; the transparency at the same time diminishing in a slight degree. ' The specific gravity varies from 1.16 to 1.54in the dark-red varieties. In the flame of a candle it takes fire, burns afterwards of itself with considerable smoke, and an aromatic, slightly em- pyreumatic, odour, leaving a small coaly residuum. On the sand bath, in a close tube, it gives off a small quan- tity,of a transparent, colourless, and highly. volatile naptha, having a peculiar odour, resembling that. of some kinds of strong cheese. Heated to 400°, it does not melt, but assumes a bright black colour, though, when broken into fragments, it still transmits a rich red light. Over.a spirit lamp it fuses, gives off a colourless nenahes a ted empyreumatic oil, and leaves much charcoal. It is insoluble in water, and is very slightly acted on by Mr Johnston on a new variety of Mineral Resin. 123° ‘alcohol or ether.» By hot concentrated nitric acid it is slowly, but entirely dissolved. - When rubbed it exhibits strong negative electricity. «Dr Brewster informs me, that, like amber, it has no crystal. ‘line structure. ©. This substance occurs along with brown spar (carbonate of -iron,) and carbonate of lime; either in the form of little drops ‘on the surface of the brown’ spar, where cavities occur in the -vein, or in the midst of the massive brown spar, as if it formed _part of the solid stone. In one specimen it rests ‘upon car- bonate of lime, containing crystals’ of Galena, and is covered with a mass of brown spar. The brown spar in these cases forms thin layers, seldom ex- ceeding an inch in thickness, either coating the surface of the blocks of trap which have been excavated,-or alternating 1 irre- gularly with thin portions of the same rock. The resinous matter has most probably an origin similar to that of common petroleum often found in various forms in lead veins ; and . the whin dike associated with or crossing the vein in this mine, appears to be connected with its formation. The position of the substance imbedded in stone, shows it to have remained in the same state for many ages ;—it may be since the wall of ‘trap began to cool. It is easy to see, that, on the eruption of ~such a dike of fluid matter, every combustible substance which ‘came in its way would be decomposed, if susceptible of decom- “position, and be driven into vapour; and that these vapours *being confined where they had no outlet to the surface, must -afterwards condense as the heat diminished, into oily and resi- ‘nous substances of various kinds. At Chapel Lime Quarry near Kirkcaldy, where the ater “petroleum is found in some quantity, a product very similar to that above-described is occasionally found. ‘The only specimen _ of it I have seen is in the possession of Mr Rose, mineral- _ dealer, and is in the form of small specks scattered here and there on crystallized carbonate of lime from that quarry. It is generally lighter coloured ; but one small morsel is of the bright and beautiful red of that collected at Settling Stones. The only mineral résin resembling the present, of which I have seen any description, i is the ie le copal, or Highgate » resin, found at Highgate in blue clay. The latter, however, 124 Dr Thomson on Improved Methods of melted by heat into a limpid fluid, a character which shows it to differ very much from that above-described. The vegetable origin of amber seems now established. beyond dispute. The collection of embalmed insects belonging to the University of Upsala, or the equally splendid private collection exhibited by Dr Berendt of Dantzick, at the late meeting in Hamburgh, appearing sufficient of themselves to convince the most sceptical. Yet it is not surprising that the occurrence of resinous substances like the foregoing, whose origin is incon- trovertibly mineral, should be sufficient to lend plausibility to the opinion that amber is of mineral origin also. PortoBELLo, 7th December 1830. ‘Art. XIT.—On Improved Methods of computing the Angles of Spherical Triangles when the sides are given. By. James Tuomson, LL.D. Professor of Mathematics in Belfast College. (To the Editor of the Edinburgh Journal of Science, ) Sir, As even slight improvements in the solution of problems which are of frequent occurrence in practice, are of some im- portance, the following methods of computing the angles of plane and spherical triangles, when the sides are given, may in- terest some of your readers, they are contained in a small work of mine on Plane and Spherical Trigonometry, publish- ed a few months ago, and, so far as I know, they are new, with the exception of formulas (1) and (4.) Let the angles be denoted by A, B, C, and the opposite sides by a, 6, c; let alsos=} (a+6+¢): then, I. In a plane triangle, tn fA = COS? kai reece SS tan 5 B= oe - ae - (2.) tan} C= pees - . hae (3-) where N = (s—a) tan } A. computing the angles of Spherical Triangles. 125 wo II. In a Spherical Triangle. preety A= a sin (s—b) sin (s—c) sin § sin (s—a) (4) . N’ tang B= sin (6—b) (5.) 4 fF LN’ tan} C= sin (9c) (6.) where N’ = sin (s—a) tan } A. The first and fourth of these are given in all the works on trigonometry. ‘To find the others we have in a plane triangle, according to (1.) , se se) n}Oe (s—a) s—b tan } B= J Pet ae tan} 0=V OS and in a spherical triangle, according to (4.) ip ,sin(s—a)sin (sc) 1 sin’(s—a) sin sb) ricer sin s sin (s—6) mind ated sin § sin (sc) Hence, by dividing successively the members of the first pair by those of (1,) and the members of the second pair by those of (4,) we obtain in the plane triangle, tan; B s—a tan} C s—a tan} AW~ s—v’ tani A sae and in the ebbicedesd triangle, tan $B __ sin (s—a) tanZC sin (s—a), tan} A™~ sin (s—d) tan} A sin (s—c)’ from which, by multiplying by tan } A, and denoting the common numerators (s—a) tan } A, and sin (s—a) tan } A by N and N’, we get the remaining formulas. To exemplify these principles, let the sides a, 6, c, of a plane triangle, be 679,537, and 429, to find the angles. These data give s — 822.5, s—a = 143.5, s—b = 285.5, and s—c = 393.5; * and the rest of the work, by logarithms, stands as follows: * In both plane and spherical triangles, the sum of the three remainders, s—a, s—b, s—c, is equal to the half sum s ; and hence we have an easy mode of verifying the preparatory part of the computation. 126 Dr Thomson on Improved Methods of 5, 822.5 2915136) tanZA -. =. 9.989281 s—a, 148.5 2.156852 ; Subt. log (s—a) = ef Add. s—b, 285.5 2455606 —_— s—c, 393.5 2594945 log N+10 = 12146133 © — log (s—b) = 2455606 \ —_2)19.978563 —_—— tan 3 B 26°73’ = 9.690527 © tan} A44°173' 9.989281 B= 52° 15’ ' A = 88°35. lg N+10 - 121461383 | log(s—c) - 2594945 — tan} C 19°38’ 9.551188 C == 89° 10° In this operation only four numbers are required to be taken from the tables, those employed in the second column being all found in the first ; and hence the great facility of the method is obvious. ‘The angle C might be obtained from A and B. As it is found, however, with such ease as above, it is better thus to compute it, since the addition of the three angles affords a complete verification of the process. As a second example, let the sides of a spherical triangle be 100°, 37° 18/, and 62° 46’. - Here we have s = 100° 2’, s—a — 2’, s—b = 62° 44 and s—c — 37° 16’; and the rest of the work is as follows: ° 4 sin S$ 100° 2’ 9.993307 sin (s—a) 2 6.764756 sig Sak yor sin(s—b) 62 44 9.948845 sin (s—c) 37 16 9.782132 F 22.972914 tan} A 88° 7 58” | 11.486457 = 176715! 46” add sin (s—a) 6.764756 log N’ 48.251213 sin (s—b) 9.948845 5 SUPttact tan}B 1° 8’ 57” 8.802868 B= 2°17 54” log N' Nichia FY et sin (¢—c) 9.782132 ¢ Subtract. tn }C 1°41’ 18" 8.469081 C = 3° 22’ 26” computing the angles of Spherical Triangles. 127 In this example, as in the foregoing, only four logarithms are to be taken from the tables for finding all the angles; and the arithmetical operations are of an easy kind. It is plain, that when the three angles are given, the sides may be found by a process resembling the foregoing, and equally easy. JAaMEs THoMson. ~ Betrast, Nov. 26, 1830. I beg to add also the following extract from ‘* An Introduc- tion to the Differential and Integral Calculus,” which has been just published, relative to a subject of some interest in the history of science. ‘¢ 394. Given the latitude of a place, and two circles parallel to the horizon ; to find the declination of a body which, in its apparent diurnal motion, will pass from one of them to the other in the shortest time possible.* “Let Z and P be the zenith and pole, and S and 8S’ the required points on the given parallels, having equal ‘polar distances, PS and PS’. Now, since the time of describing the * «* A single case of this problem, viz. to find the day of shortest twi- light in a given latitude, employed, for several years, the two brothers, James and John Bernoulli, without success. By treating it algebraically, they were led to an equation of the fourth order, in which they were em- barrassed to separate the useful roots from those which ought to be reject- ed ; but, afterwards, by employing the synthetic method, they separately obtained answers very convenient for astronomical computation. In the year 1780, Fontaine attempted a solution by algebraic analysis. In this manner, he obtained an equation of the fourth order, which he required twenty quarto pages to reduce and explain.’ —The foregoing extract is taken from’a paper in the Mathematical Companion for 1805. Much information on the subject, with several solutions of the problem, will be found col- lected in the fourth volume of Leybourn’s edition of the Mathematical Questions proposed in the Ladies’ Diary. The method of solving this and similar problems, which is here given, was first pointed out by the author of this work, in the Belfast Almanac for 1828 and 1829. It has the advan- tage of extending the general method of determining maximums and mini- mums to a class of problems to which that theory was never applied suc- cessfully before, and of solving questions, once considered extremely diffi- cult, in a more direct and, perhaps, more simple way, than by any other method that has yet appeared ; thus affording a striking instance of the great power and excellence of the modern methods of investigation, when properly applied.” 128 - Dr Thomson on Improved Methods of arc S S’ is a minimum, the angles S P S’ must also be a mini- muni. Hence (Sect. VIL. im dS PS! Seed dP’ dP es 5 or bat = 0; whence =~ = aay! wha P and P” denote the anglés ZPS and Z PS, and « the polar distance PS or PS’. Now, putting the latitude = J, ZS =a, and ZS’ =a’, we have (formula 2, page 23) dP. .,,,cot$ sna te we cot S’ ot da. : tan 9° : —sin dec. ‘© 394. * Given the latitude of the place, and the positions of twohour circles with respect tothe meridian ; to determine the de- sin Z, cos @ — computing the Angles of Spherical Triangles. 129 clination of that star whose change in altitude shall.be the greatest possible in passing over the interval between those _“ Here, in addition to the notation adopted in the last No. let Z S and ZS’ be represented by z and x ; and the angles PZSand PZ 9S’, by Zand Z’. Then, since Z S’'—Z S is a maximum, it might be shown, as in the last problem, and by formula 13, page 24, that dz dz d 2! dz dz’ dz whence cos S’ = cos S, and S’= S. Now we have = cos §’/, and acid cos S$; tan /sin c—cos P’ cos x. —, and cot S’ ———__—.. = sin. P’., tan / sin z—cos P cosx sin P cotS= By putting these equal to each other, dividing by sin a, multi- plying by the denominators, and transposing, we get (sin P/ cos P—cos P’ sin P) cot 2 = (sin P’—sin P) tan /, or sin (P’—P) cot #— (sin P’—sin P) tan J. Hence we obtain, by dividing by sin (P’—P), and by Trico- NoMETRY, No. 28, Cos 3 2 (P+ +P) cos 1 (P’—P) * This question is taken from Gregory's T'rigonometry, page sin } (P’—P) sin }(P’ PY cot x, or tan dec. = tan /. 243, where an erroneous answer, tan dec. — tan J, is given. * Since S = S’, it would appear, by means of the formalas of the four sines that Z=x—Z’; whence it appears, that the azimuths of the body at the required positions are supplements of-each other. It is also plain, that, if the an- gle S PS’ be bisected by the are P Q, we shall have tan da ee cosZ PQ SPQ’ eliniatienl must be nothing for every value of P and P’; and that, if P=P’, the formula will become tan dec. = cos P tan J, an expression which will determine the declination of a star that, in crossing a given hour circle, will be increasing or diminish- ing its altitude more rapidly than any other star would in eros- sing the same hour circle. In this last case, it is evident, from NEW SERIES, VOL. Iv. NO, 1. JAN. 1831. I . tan/; that, at the equator, when 7=0, the de- 130 Professor Berzelius on Bodies having a the equation, Z=*—Z, that the star will cross the given hour circle and the prime vertical atthe same time. Similar results for particular cases, besides that of the shortest twilight, might be derived, in a similar manner, from the solution of the pro- blem in the last No. Other questions of this kind will be found in the next Section. Art. XIII.— Some general Remarks on Bodies having a like Composition, but unlike Properties. By Professor Brr- zELIus of Stockholm.* By Isomeric (sowegnc) bodies, I understand those which, with a like chemical composition and atomic weight, possess unlike properties. There exists another class of bodies which, while they have the same composition per cent., have different weights. These are for the most part multiples of one ano- ther. Of this kind is carburreted hydrogen (Car. + 2 Hyd.) which, if the analyses are correct, forms, 1. Olefiant gas; 2. Another light gas, which condenses into an oil, with an atomic weight double of the former; 3. One or more crystalline bo- dies. These I do not include, since they must be better studied, and then probably distinguished by a new collective name. . Although we have for several years possessed well authen- ticated examples of isomeric bodies in the two different oxides of tin, composed of one atom metal and two atoms oxygen, as well as in the fulminic. and cyanous acids, yet Clarke’s paper on the difference between the common and the ignited phosphate of soda, his pyrophosphate, must be considered as having first led to a nearer study of these bodies. The para- tartaric acid has presented itself at a seasonable time to throw farther light and certainty upon the matter. The number of bodies which give isomeric combinations is probably great, though they have hitherto been little studied. I have several times observed that the ammonia sub- phosphate of magnesia, when first gently heated in a platinum crucible, to drive off the ammonia, and afterwards strongly ig- nited, showed the phenomena of ignition which I first ob- * From a paper in the Transactions of the Swedish Academy, 1830. like Composition but unlike Properties. 131 served in some of the salts of the antimonic acid, and which has been since noticed in regard to zirconia, oxides of chro- mium and iron, carburet of iron, &c. In the phosphates, I could not reproduce this phenomenon at pleasure, and, therefore, I cannot give it as a property necessarily connected with their existence. It is enough for our present purpose that it occasional- ly takes place. It appears to indicate the ¢ransition from one isomeric modification to another, while the paraphosphate* which was put into the crucible is changed by ignition into the phos- phate. It is probable, therefore, that all bodies which exhibit this phenomenon pass into another isomeric modification ; al- though it does not follow from thence that this transition is al- ways accompanied by the evolution of light, since we know that a chemical combination is often so accompanied, though in the greater number of cases it takes place without any of the phenomena of ignition. It is further probable that the speedy, yet permanent changes which certain bodies undergo by heating in liquids, during which, like the white of the egg, the colouring matter of the blood and fibrin, they pass from the soluble to the insoluble state, may be owing to a transition from one isomeric modification to another. On the other hand, the different dimorphous salts do not belong to this class of bodies, since their differences are entirely mechanical. and disappear by solution. A very important, but as yet unanswerable question is, ** Can the elements exist in two different states?” In one point of view this idea has no great degree of probability, and yet there are many facts which may be brought forward in support of it. For example, the different states of carbon in diamond and graphite, the differences in metallic platinum reduced, in the moist way from its salts by alcohol, or by igniting the double ammonium chloride ;.the differences in other metals, as, for ex- * In another part of his paper, Berzelius proposes to distinguish the iso- meric bodies by the particle zagz, denoting change, affixing it to that which has been modified and undergone the change where it can be ascer- tained. Hence, he names the pyrophosphoric simple phosphoric, as being the state of the newly prepared acid; the common phosphoric he names paraphosphoric, as being modified in some way by the agency of water. In the same way he calls the oxide of tin, thrown down by potash from the yolatile chloride, the oxidum parastannicum. 132 Professor Berzelius on Bodies having a ample, iron, according as it is reduced by hydrogen gas at a higher or a lower temperature; the dissimilar states of titani- um and tantalum, when they are reduced by kalium, and after- wards freed from: the latter by water, or when they are ‘re- duced by charcoal at a higher temperature, the unlike com- bustibility and solubility in fluoric acid of silicium before and after‘ignition, &c. &c. ) + wi Although, on the one hand, it must be asi that these ‘differences: may be accounted -for by a dissimilar aggregation of the particles of bodies, yet, on the other hand, it must be remembered that the atoms of simple bodies may possibly, under different circumstances, be grouped together in more than one way for the formation of regular forms, and that groups united in different ways may produce different: rela: tions to light, and a different tendency to combination: with other bodies. . shay ses The following bodies, in addition to the tartaric sail para- tartaric acids, hang already been ascertained to et to ee which undergo isomeric modifications. , 1. Owide and Chloride of tin were the first bodies in which similarity of composition was ascertained with certainty to accompany dissimilar chemical properties. Of these differ- ences I have given a circumstantial detail in my System»of Chemistry. 'They came too unexpected to-draw forth any re- marks, and many have probably thought the statements: found- ed on error. les el In the titanic acid Heinrich Rose has found analogous iso- meric modifications. 2. Cyanous and Fulminic sid form bibothes well establish. ed example; and yet even this only gave birth to’ suspicions that there might be some errors yet undiscovered in the ana- lysis which: pointed them out as isomeric. 8. The Phosphoric acid gave birth to the idea of a like composition with unlike chemical properties. On this subject, Stromeyer has expressed himself the most decidedly. Accord- ing to him, the difference lies not in the relation of the com- ponent parts, ‘ but in the different: ways in which they com- bine, and in the unlike condensation they have undergone.” * * See Stromeyer’s paper in the preceding number of this Journal, p. 319. like Composition but unlike Properties. 133 ‘ With regard to the unlike condensation, it can be under- stood only of the phosphoric ‘acid itself, and not of its compo- nent parts. On the other hand, Stromeyer has much darkened the question concerning these appearances by the experiments he has undertaken, since he draws from them the conclusion which very few will share with him, that these acids possess different capacities of saturation. These capacities he expres- ses by the quantity of oxide of silver which saturates 100 parts of the ignited and the common acids, (the phosphoric and paraphosphoric of Berzelius) and which, for the former, is 306.338, and for the latter, 504.412 parts. However, the capacity of saturation does not alter when the common phos- phate of soda is changed by ignition into the other salt. I have, besides, in regard to the quantities of oxide of silver men- tioned by Stromeyer, to remark, that they are incorrect not only in reference to the phosphoric acid when my atomic weight is taken, but also in regard to one another, so that they do not both correspond to the same atomic weight. Again, as to the yellow phosphate of silver, I have already long ago * analyzed this compound, and found that 100 parts of phosphoric acid take up only 488 of oxide of silver. In regard to the atomic weight, Stromeyer’s result is the mean of three experiments made in different ways, in which the quanti- ty of oxide of silver differs half-a-per cent (from 83.183 to 83.712.) Errors of observation so large are now no longer admissible in chemical analyses, when these are so easily exe- cuted as in the present instance. I have therefore thought it unnecessary to confirm my old observations by any new ana- lysis. The yellow phosphate of silver is Ag® P® (a dises- qui-phosphate.) The same objection lies against Stromeyer’s analysis of what he calls the pyrophospate of silver, since he, from 100 parts of ignited phosphate of soda, by precipitation with nitrate of sil- ver, obtained in one experiment 223.11, and in another 221.06 phosphate, (pyrophosphate, *) of silver. Here is again a difference of half-a-per cent. in results obtained in the same manner. * Afhandlingar i Fysik, Kemi och Mineralogi, v. p. 400. + In page 323 of our preceding oneal, 222.085 alone, the mean of these two results, is given. 134 Professor Berzelius on Bodies having a Since I had no previous opportunity of analyzing this salt, I have lately investigated it, and found that the ignited phos- phoric acid forms no less than three combinations with oxide of silver,—a neutral, a bi, and a sesgui salt. The last two are decomposed, though very slowly, by pure water, and, with- out considerable care, one may easily obtain a mixture of them with the neutral salt. The bi-phosphate (bi-pyrophosphate of Stromeyer and others) is thrown down when a solution of ignited phosphoric acid in water is mixed with a solution of nitrate of silver. It may be washed with cold water till all the nitrate of silver is dissolved, without more than a very small portion of the salt being de- composed, At 100 C. (212 F.) it becomes soft and semifluid, and at a higher temperature it melts into a colourless and transparent, fluid, which congeals on cooling into a brittle solid exactly resembling crystal glass. By an analysis of this salt I obtained 64.517 oxide of silver, and 35.483 phosphoric (pyrophosphoric) acid. Had the salt not been decomposed by the washing, I ought to have obtained 61.932 oxide of silver, and 38.068 phosphoric acid. The sesquiphosphate, (sesquipyrophosphate,) is obtained by pouring boiling hot water on the newly precipitated biphos- phate; by which means it is converted into a gummy unctu- ous turpentine like grey mass. This fused substance is sesqui- phosphate, except in its inner parts, where, from the toughness of the substance preventing the water from reaching it, a little bi-phosphate remains. After treating for a short time with hot water, it is washed with cold, and is then much more diffi- cult of fusion alone, than under warm water. The fused salt consists of 69.583 oxide of silver, and 30.417 phosphoric acid. If entirely free from ‘bi-phosphate it should have given 70.933 base, and 29.067 acid. Lime, it is known, gives a similar tur- pentine-like clammy sesquiphosphate. These salts were analyzed by solution in nitric acid, and precipitation of the silver in the state of chloride. 1 have not gone into the details, because it is impossible to obtain these salts perfectly pure, so that the results can only be regarded as an approximation. Neutral phosphate, (pyrophosphate,) of silver is obtained . like Composition but unlike Properties. 135 by mixing a solution of pure ignited phosphate of soda, with a solution of pure, previously fused, nitrate of silver. The precipitate must be well washed, melted, when it gives an opaque glass resembling enamel, rubbed to powder and weigh- ed in this state. Since Stromeyer in his experiments takes the double atom of chlorine at 4.5, instead of 4.4265, and a devia- tion from the true result must therefore arise from this cause, I considered it necessary so to devise my experiment as to re- move this source of difference. I therefore decomposed the silver salt by heating with twice its weight of anhydrous car- bonate of soda, in a platinum crucible previously glazed inter- nally with carbonate of soda, that the silver might not come in contact with,.and attach itself to the crucible. After heat- ing gently for half an hour, it was brought nearly to.a state of fusion. On. cooling, the salt. was dissolved in water, the me- tallice silver, boiled out, and afterwards well washed on the filter with boiling water. 7.645 parts of the salt gave 5.435 parts of ‘silver = 5.8571 oxide of silver, and therefore 100 parts consist of 76.351 oxide of. silver, and 23.649 acid. As this is a little less than ‘76.49, the amount obtained by calculation, I treated the solution of phosphate, (pyrophosphate,) and carbonate of soda with muriatic acid, by which the fluid was rendered opalescent, showing it still contained a minute quan- tity of silver, though so small as to be incapable of accurate determination. The experiment, however, is sufficient to show that this silver salt has precisely the composition of a neutral phosphate of silver. * | ‘When the acid liquid in which the sesquiphosphate is form- ed by heat is filtered and evaporated, there forms during the evaporation a crystalline enamel-like crust, which I have ‘analyzed and found to be also the neutral phosphate. The residual liquid gave after evaporation a thick colourless syrup, consisting chiefly of phosphoric acid, which by re-solution in * The conclusion from these experiments is, that Stromeyer has erred in considering the yellow ‘phosphate to be a neutral -salt, whereas it isa bisesqui salt, and, comparing the acid it contains with that present in the last of these described by Berzelius, which is actually a neutral salt, has deduced from this comparison the erroncous result, that the two phosphoric acids have different atomic weights or capacities of saturation. (See No. vi. p- 323.) Tran. 1386 ~° Dr Brewster on the Phenomena and Laws water left a gelatinous, but not yellow silver salt, which I have not yet analyzed. I may here mention as a conjecture, that, although no iso- meric combinations have yet been discovered of the arsenic . acid, corresponding in their relations to oxide of silver with the ignited phosphoric acid, it would appear from the dif- ferences in its appearance, and its unlike solubility in water, that the arsenious acid is susceptible of two isomeric modifi. 3 cations. 4, Cyanogen, according to the experiments of J lunuan|* may be obtained in two isomeric modifications, of which the one is gaseous cyanogen, and the other a solid black coaly looking mass, which remains on the decomposition of cyanide of mercury by distillation. 5. In organic nature, there appears to exist a great many isomeric bodies. ‘The tartaric and paratartaric acids are the first accurately determined examples, but in/a short time we are certain of finding more. Thus, for example, Prout has found that cystallized grape and diabetic sugars have precise- ly the same composition as milk sugar. Both contain water, the amount of which in grape sugar, is not ascertamed. But if it be the same as in milk sugar, then it will-follow that wee bodies belong to thie class I have called isomeric. Arr. XIV.—On the Phenomena and Laws of Elliptic Pola- rization, as exhibited in the Action of Metals upon Light. By Davin Brewster, LL. D. F. kK. S. Lond. and Edin. + F rom the first dawn of the science of polarization, the action of metals upon light has presented a troublecome anomaly. Malus at first announced that they produced no effect what- ever; but by employing a different method of observation, I found that the light reflected by metallic surfaces was so far modified as to produce, when transmitted through thin crystal- lized plates, the complementary colours of polarized light. From a second series of experiments made previous to mine, * Edin, Jour. of Science, N. S. July 1829, p. 119. + From the Phil. Trans. 1830, p. 287. Read April 22, 1830, 3 7S *.. of Elliptic Polarization. 137 Malus came to the conclusion, that the difference between transparent and metallic bodies consisted in this: that the for- mer refract all the light which they polarize in one plane, and reflect all the light which they polarize in another ; while me- tallic bodies reflect what they polarize in both planes. Having: discovered the property of transparent bodies to polarize light by successive reflexions at angles at which a single reflexion produced no perceptible, effect,* I resolved to apply this method of examination to metals; and on the 7th of February 1815, when I first made the experiment, I dis- covered the curious property possessed by silver and gold of dividing a polarized ray into complementary colours by suc- cessive reflexions. As this subject promised to open a wide field of inquiry, I prepared for the ardent prosecution of it with all the metallic bodies which could be procured ; but the pres- sure of professional business prevented me for about a month from doing any thing very effectual. On the 6th of March 1815, I received a letter from M. Biot, requesting some information on a matter of business ; and in answering this letter on the same day, I communicated to him an account of the discovery above-mentioned.+ Immediately after this I received the most perfect plates of silver, one pair polished by friction, and another by hammering ; two pair of plates of gold, one of jewellers’, and another of fine gold; with plates of steel, platinum, palladium, copper, brass, and speculum metal ; and with their help I obtamed the general result, that a single reflexion from a metallic surface produces the same effect upon polarized light as a certain thickness of a crystal- lized body, with many other results, which it is unnecessary here to indicate. As soon as M, Biot had received notice of my discovery he seems to have devoted himself to the same inquiry ; and with all the leisure of an Academician, and the splendid appa- ratus presented to him by the Institute, he obtained many of * Phil. Trans. 1815, p. 142. } It is related in the History of Optics, Zdinburgh Encyclopedia vol. Xv. p. 493, note, that I communicated this discovery to M. Biot on the day on which it was made ;—this is a mistake, as it was done a month afterwards. 138 Dr Brewsenion wie (Pkahiiiine and Laws the results at which I had arrived, and others to which I have no claim; and on the 29th of March he transmitted to me, through Dr Wollaston, an open letter containing an abstract of: his experiments, and expressing the hope that they would be of use to me in my. researches. Although: this expression led me to believe that I should enjoy the privilege of publishing the first account of my own discovery, yet I took the precaution of having all my papers on the subject signed by the Treasurer of the Royal Society of Edinburgh, and I proceeded with new zeal in the further examination of’ the subject. 1 soon learned, however, from M: Biot, that he meant to treat: the subject. in his T'raite de Physique ; and though I remonstrated against this as a breach of courtesy, I had the mortification to see the discovery, to which I perhaps attached too much importance, published for the first time in a foreign work. I trust the Society will excuse these details as.a necessary apology for having so long delayed to fulfil the promise, more than once made in their T'ransactions to communicate to them an account of these experiments. * The reasons which I have assigned were subsequently strengthened by new in- quiries which at first threw great doubts over the views which M. Biot and I had taken of the subject, and finally convinced me of the rashness of our generalizations. The study of M. Fresnel’s fine discoyeries respecting circular polarization ena- bled me to advance still further in the inquiry ; and having more recently resumed the investigation, I trust I shall now be able to present to the Society a satisfactory analysis of the singular phenomena exhibited in the action of metals upon light. * In a letter to Sir Joseph Banks, dated July 28th, 1815, I communi- cated an abstract of these and other experiments, with a request that he would permit the MS. to remain in his possession, as an evidence of my claims. Sir Joseph: complied with this request: but nearly two. years afterwards, happening to see the MS., he thought that it had been intend- ed for publication, and laid it before the Royal Society without my know- ledge. It was accordingly read on the 23d of January 1817, under the title of Abstract of Experiments on Light, and ordered to be printed. When the proof-sheet was sent me for correction, I requested the eth to be cancelled, as it was not intended for publication. of Elliptic Polarization. 139 Sscr, I.—On, the action of metals upon common light. When we analyze with a rhomb of calcareous spar a ray of common light, reflected at different angles from a metallic sur- face, there will be observed in one of the images a defalcation of light, as if a portion of the incident ray was polarized in the plane of reflexion. This effect will be still more distinctly seen if we examine the system of polarized rings formed round the axes of crystals by means of the light reflected from metals. If the light had suffered no modification by reflexion, or if the metal reflected in equal quantities the light polarized in oppo- site planes, the rings would not be visible at all; but it will be found that they are easily seen in the light reflected by all metals. They are most distinctly visible at an incidence of about 74°, at an average, and become fainter and fainter as the incidence exceeds or falls below that angle. They appear best defined in light reflected from galana and metallic lead, and with least distinctness in light: reflected from silver and gold, as shown in the following Table, in which the metals are arranged’ in the order in which they exhibit the rings most brightly, and consequently in the order in which they polarize the greatest quantity of light in the plane of reflexion: Galena, Antimony, Bismuth, Grain tin, Lead, Steel, Mercury, Jewellers’ gold, Gray cobalt, Zine, Copper, Fine gold, _ Arsenical cobalt, Speculum metal, ‘Tin plate, Common silver, Iron pyrites, Platinum, Brass, ... Pure silver; If we now take two plates of each of these metals and iexa- mine the light which has undergone more than one reflexion, we shall find that the quantity of hight which each polarizes in the plain of reflexion increases ‘with each reflexion, and that in several of them the whole incident pencil is completely polarized. When the luminous object is a wax-candle placed at the dis- tance of ten feet, eight reflexions from a plate of steel at angles between 60° and 80° polarize the whole of the light, while at angles above 80° and below 60° a greater number of reflexions is required. With galwna, lead, cobalt, and antimony, a much smaller number of reflexions polarizes the whole pencil; whereas with pure and highly polished silver a very great num- 140 Dr Brewster on the Phenomena and Laws ber is necessary: the light reflected from the silver becomes redder and redder, indicating an increasing —— or dis- persion of the less refrangible rays. By the use of common light it would be in vain to attempt to discover the law according to which the polarization of the incident pencil is effected in different metals ; but by another mode of analysis we shall be led to the mathematical law for computing the exact proportion of the reflected pencil which is polarized at certain angles when the number of reflexions exceeds one. Secr. II.—On the action of metals upon polarized light. Pe If a pencil of polarized light is received on a polished me- tallic surface placed so as to have a rotatory motion round the polarized ray, the reflected light will receive no modification, (excepting what arises from its property of apparently polariz- ing a portion of light in the plane of reflexion,) when the plane of incidence is inclined 0°, 90°, 180°, and 270° to the plane of primitive polarization; but in every other, azimuth of the plane of incidence the reflected pencil will be found to have suffered a remarkable change, which gradually increases as the azimuth of that plane varies from 0° to 45°, from 90° to 135°, from 180° to 225°, and from 270° to 15°. At the azi- muths of 45°, 135°, 225°, and 315°, the. effect is a maximum, and it gradually diminishes from 45° to 90°, from 135° to 180°, from 225° to 270°, and from 315° to 360°. In order to investigate the nature of this change, we shall suppose the plane of reflexion from the .metal to be inclined — 45°, or to the left of the plane of primitive polarization. In this position let a plate of highly polished steel receive the polarized ray of ordinary intensity. At 89°, 83°, and 87° of incidence, almost no change is produced upon it by the action of the meta]... We can easily see that the plane of po- larization of the ray is turned from right to left, exactly as it would be by a transparent surface. In like manner, at all angles of incidence from 0° to about 40° no decided effect is produced, except the change in the plane of polarization. At angles less than 87° the change begins to appear, reaches its maximum at about 75°, and diminishes gradually to 40°. . By of Elliptic Polarization. 141 means of the analyzing rhomb, it is easily seen that a great portion of the original pencil has had its plane of polarization changed from: + 45° to 0°, as the incidence diminishes from 75° to 0°. If, indeed, we measure the rotation of the princi- pal section of the rhomb when the extraordinary pencil is a minimum at different angles of incidence, we shall find it to correspond with - 45° — 9, 2 being calculated from the formula Sint = 3. (oe, the index of re- fraction for steel. The value of ¢ will be found to be nearly | the same at 87° and 40°, which shows why at these two angles the change under our consideration is just beginning to appear with light of ordinary intensity. “Phe physical effect of the metallic surface being a maximum _ at 75°, we’ shall now examine the character of the pencil re- flected at that angle. ‘1: The’pencil thus reflected is not polarized light, because it does not vanish during the revolution of the analyzing rhomb. 2. It is not common light, because when we reflect it a second time at 75° from another steel surface, it is restored to light polarized in one plane. In order to discover its nature, let it be transmitted along the axis of calcareous spar. The system of rings is changed almost exactly in the same manner as if a thin film of a crys- tallized body which polarizes the pale blue of the first order had crossed the system. If we substitute for the calcareous spar films of sulphate of lime, which give different tints, we shall find that these tints are increased according as the me- tallic action coincides with, or opposes that of the crystal. On the authority of this experiment I was led to believe that metals acted upon light like crystallized plates; and when I found that the colours were not only better developed, but more pure after successive reflexions, it was a natural, though a rash, generalization, to conclude as I did, and as M. Biot did after me, that each successive reflexion corresponded t to an additional thickness of the crystallized film. In order to show the incorrectness of this deduction, let a ray polarized’ + 45° be reflected twice from: steel an angles of 142 Dr Brewster on the Phenomena and Laws 75°. In this case the effect of the second reflexion should be to double the tint produced by the first, if the tints are those of crystallized plates. The result, however, is, that the whole of the light is polarized in one plane, in place of consisting of two pencils’ polarized in opposite planes. M. Biot got over this embarrassment by regarding the tint produced by two re- flexions as the white of the first order, which, in consequence of its complementary tint being black, is the only one where the light is all polarized in one plane: but had he examined the light reflected four times, six times, or eight times at '75°, he would have still found it all polarized in one plane, a result entirely incompatible with the supposition of the tints rising with the number of reflexions. That the tint is not the white - of the first order may be more easily proved by making it pass along the axes of the calcareous spar; for we shall find that in place of producing an increment of tint, the effect of the second reflexion has been to destroy entirely the effect of the first, and to restore the ray to common polarized light. All this will appear by the perfection of the system of rings seen through the spar. If we examine ima similar manner the light which has undergone any number of reflexions between the plates, we shall easily ascertain that the effect never exceeds that of a quarter of a tint in Newton’s scale. Having thus ascertained that light polarized + 45°, and re- flected at the maximum polarizing angle of metals, is neither common light nor- polarized light, nor light constituted like that which passes through thin crystallized plates, I conceived the idea of its resembling circularly polarized light—that re- markable species of light which comports itself as if it revolved with a circular motion during its transmission through parti- cular media. According to Fresnel’s beautiful discovery, a ray of light polarized + 45° is circularly polarized when it has suffered two total reflexions from glass at an angle of 543°; and when such a ray is made*to suffer other two reflections at the same angle, it is restored to the state .of light polarized — 45° to the plane of reflexion,-whatever be the azimuth of the second plane of reflexion in relation to the first. In like manner I shall proceed to show that a ray of light polarized + 45°, and ‘of Elliptic Polarization. 148 reflected once at the maximum polarizing angle from metals and certain metalic ores, has an analogous polarization, viz. a polarization hitherto unrecognized, and intermediate between circular and rectilineal polarization. Let the ray polarized + 45° be reflected at '75° from steel, and let a second plate of steel be made to turn round the ray thus reflected. At the azimuths of 45°, 135°, 225°, and 315°, with the plane of primitive polarization, that is, when the planes of the two reflexions are either coincident or rectangular, the first reflected ray will be restored to polarized light at an incidence of ‘75°. At azimuths of 0° and 180° the restoration will be effected at an incidence of 80°, while at azimuths of 90° and 270° it will take place at an incidence of 70°, and at interme- diate azimuths it will take place at intermediate incidences. Hence the ray of light reflected from steel, though it has the general properties of a circularly polarized ray, differs from it im this remarkable particular, that it requires different angles of incidence in different azimuths to restore the polarized light. — In circular polarization, as we have seen, the ray has the same properties in all its sides; and the angles of reflexion at which it is restored to polarized light in different azimuths are all equal, like the radii of a circle described round the ray. Hence, without any theoretical reference, the term circular polarization is from this.and other facts experimentally appro- priate. In like manner, without referrmg to the theoretical existence of elliptic vibrations produced by the interference of two rectilineal vibrations of unequal amplitudes, we may give to the new phenomena the name of elliptic polarization, because the angles of reflexion at which this kind of light is restored to polarized light may be represented by the variable radius of an ellipse. In circular polarization the restored ray has its plane of po- larization always inclined — 45° to the plane of the second sys- ‘tem of reflections. In elliptic polarization the difference is remarkable. The inclination of the plane of the restored pen- cil is likewise —, but always less than 45°, as will appear from the following Table, which contains the greater number of metallic bodies : Let 144 Dr Brewster on the Phenomena and Laws Names of: Angles of — , Names of Angles of Metals. Restoration. Metals. Restoration. . Total reflexions 45 0 Bismuth 4 2 0. Pure silver 39 48 Speculum metal 21. 0- Common silver 36 0 Zines: istoe 19 10 Fine gold 35 0 Steel i go RF O _ Jewellers’ gold. 33 0° Tron pyrites 14 0 Grain tin 33 0 Antimony 16 15 Brass + 32 0 Arsenical cobalt 13 0 Tin plate 31 0 Cobalt a 12 30 Copper » 29° 0 Lead oi 11 0 Mercury site 26.4: :0) Galena i 2 0 Platina = 22 0 Specular iron 0 0. The bodies in this Table are obviously in the inverse order according to which they polarize most pat in the plane ee re- flexion. I have inserted at the top of the Table the fudtithatld of the restored pencil in total reflexions, which is 45°; and at the bottom, that of specular iron, which is 0°; in order to show the transition from elliptic polarization to circular polarization on the one hand, and to rectilineal polarization on the other. In these experiments the primitive ray was polarized 4+ 45° to the plane of reflection; but when this angle diminishes, the plane of the restored ray approaches to the plane of reflexion, and ultimately coincides with it at 0°; and when this. angle increases, the plane of the restored ray recedes from the plane of reflexion, and the two planes form an angle of 180° when the other angle becomes 90° The following experiments were made with plates of pure silver, in which the inclination 9 was 39° 48’, when the incli- nation # of the plane of polarization was 45°. Inclination x of the Plane Observed Inclination of — Inclination ¢ caleu- of primitive Polarization the restored ray to the lated by the to Plane of Reflexion. Plane of reflexion or ¢. Formula. + 90° 90° 0 —90° 0 85 84 36 84 0 75 74 10 72 10 65 63 51 60 46 of Elliptic Polarization. 145 55° 52° 18 49° 5'7/ 45 é= 389 48 39 48 9) 82 23 ‘30 28 25 23 10 21 14 15 13 16 12.35 5 4 40 4 10 0 0 0 0 0 Calling ¢ the inclination or value of ¢ at 45°, we may repre- sent these observations by the formula, tan 9 = tan é tan a, and the actual change of the plane of polarization, or R, will be R—=@ + 9 When ? is given, tan # = — , consequently tan g = 1, we have, cot a = tan 4, and w = 90°—#. Since light polarized + 45° is elliptically polarized by one reflexion from steel at 75°, and is restored to light polarized — 17° by a second reflexion at 75°, it is clear that a third reflexion at ‘75° will again polarize it elliptically, while a fourth reflexion at 75° will again restore it to light polarized + 9, ¢ being a quantity less than 1'7°, and given by the preceding formula. ‘The same effects will be reproduced with different numbers of reflexions, as in the following Table. and when g= 45°, and No. of Reflexions Inclination of the Plane from Steel at 75° State of the Light of Polarization. of Incidence. Reflected. Observed. Calculated. 1 Elliptically polarized 2 Restored to light polarized 17 0 17, 3 Elliptically polarized 4 Restored to light polarized +510 +45 22 5 Elliptically polarized 6 Restored to light polarized —2 0 —1 38 7 Elliptically polarized 8 Restored to light polarized 0 0 +0 30 9 Elliptically polarized 10 Restored to light polarized 00 —0O 9 11 Elliptically polarized 12. Restored to light polarized 0 0 +0 8 Hence it follows, that at every odd number of reflexions at NEW SERIES, VOL. Iv. No. I. JAN. 1831. K 146 ~ Dr Brewster on the Phenomena and Laws the maximum polarizing angle the light is elliptically polariz- ed, and at every even number it is restored to a single plane of polarization. In circular polarization the inclination 9 of this plane is always == 45°, even after fifty reflexions, as I have ascertained by direct experiment; but in elliptical pola- rization the inclination diminishes at every restoration ; and in the case of steel it is reduced to near 0° after eight reflexions, when the light is all polarized in the plane of reflexion; that is, the. elliptic polarization gradually diminishes and terminates in rectilineal polarization. The value of 9, as given in the preceding Table, po con- sequently the number of reflexions when it approaches to 0°, may be deduced from the formula, uN tan 9 = tan @. tan 2. After the first reflexion a = + 45°, and 9, or the inelination of the plane of the ray as restored by the second reflexion, is = — 17°, as given by experiment. Hence the light which _ suffers the third reflexion, and is thereby elliptically polarized, is not, as originally, polarized + 45°, but only — 17°; and consequently, when it is restored after the fourth reflexion, the value of 9 must be. such as corresponds to an equality in the values of # and ¢, both of them being = 17°. Hence the for- mula becomes, tan ? = tan’ w, or tan 9 = tan "25 n being the number of pairs of reflexions, or half the number of reflexions which the restored ray has undergone. In this way thedast column of the preceding Table has been calcu- lated. ‘The same formula represents also, as it should do, the phenomena at the limits of elliptic polarization. In the case of circular polarization, where the plane of polarization of the restored ray is 45°, we have, av — 45°, tan — 1, and tang = tan” # = 1, or 9 = 45° after any number of reflexions however great. In like man- ner, in rectilineal polarization, where # = 0°, we have g = 0°, that is, the ray is polarized in the plane of reflexion. The above formula is suited to any series of reflexions at any angle when the value of ¢ for the first: term of the series is known. The value of 9 for two reflexions, the first term of the principal series, can be determined only by experiment, of Elliptic Polarization. 147 and has been given in a former table for several metals; but we may determine from it the value of ¢ for the first term of any other series, provided it is an even number, in the following manner. Making a = the inclination for two reflexions at the maximum polarizing angle, and ¢ the value of # at any number of re- flexions 27, we shall have, tan p= ete (A) where tan ” # is the value of 9 at the maximum polarizing angle for 2 reflexions; but as no odd number can occur in the principal series, the preceding rule will not apply to such numbers. The following Table shows the coincidence between the formula and experiment. SILVER. Inclination of Plane of. Number of Values Angle of Polarization. Reflexions. of n. Incidence. Observed. Calculated. My 8oed 73.0 39 48 39 48 gion «sy 82 30 37 45 37 22 6:,; 3 85 6 35 0 35 22 STEEL. 2 1 75 0 47, ;|,0 bikes @; : 4 2 83 30. 11 30 11°17 6. & : 85 45 9 30 9 30 ~ When the number of reflexions which begin the series is odd or fractional, we must determine, by the preceding formula, the value of 9 for the even number immediately above it : and calling » the number of odd or fractional reflexions, and N the number of even reflexions immediately above », 9 the inclination fur N reflexions as given by the formula (A), and ¢ the incli- nation required, we shall have, tan gf = tana — (»— 2) ‘see ep 2) (B) The truth of this formula will appear from the following table : 148 Dr Brewster on the Phenomena and Laws SILVER. ti ‘Inclination of the Plane of Number of | Angles of Polarization. Reflexions. Incidence. Observed. Calculated. 3 79 40 38 28 $8.33 5 77 13 33 10 . 83 86 5 84) Snr. BB O 26 24 STEEL. 3 77 37 13 15 14 71 5 84 38 10 30 10 23 The same results will be obtained at the angles of equal Phase below the maximum polarizing angle. This last rule is suited to even as well to odd numbers of reflexions, but it does not give :precisely the same results for even numbers as the formula (A). The difference, however, is far within the limits of the errors of observation. The inclination, for example, at 4 reflexions, is by formula (A) 37° 22 for silver, whereas by formula (B) it is 87° 34 the dif- ference being only 12 minutes. In circular polarization, therefore, the plane of polarization of the restored light continues by successive reflexions to oscil- late on each side of the plane of reflexion with a never-varying amplitude from +- 45° to — 45°; while in elliptical polarization, the same plane oscillates with an amplitude continually dimi- nishing till it is brought to nothing in the plane of reflexion. In steel, as we have seen, the polarization is highly ellipti- cal, and the amplitude of the oscillations of the plane of resto- ration is quickly brought to zero ; but in silver, where the po- larization approaches nearly to circular, the oscillations dimi- nish very slowly in amplitude, as the following table shows. - No of Reflex. Inclination of the Plane of from Silver at State of the Reflected ‘Light. Polarization, or 9. 73° of Inci- dence. Observed. Calculated. 1 Elliptically polarized, oFnid oat’ 2 Restored to light polarized, —38 15 —38 15 3 Elliptically polarized, 4 Restored to light polarized, +31 15 +31 52 5 Elliptically polarized, of Elliptic Polarization. 149 6 ~~ Restored to light polarized, —26 0 —26 6 8 Restored to light polarized, +21 7 10 ~ Restored to light polarized, —16 56 12° Restored to light polarized, +13 30 18 Restored to light polarized, — 6 42 36 Restored to light polarized, + 0 47 Owing ‘to the high dispersive power of silver, I found it dif- ficult to carry the comparison any further with white light, as the colours closed in upon the points of evanescence, and ren- dered it impossible to determine with any precision the incli- nation of the plane of polarization. The preceding results afford the clearest explanation of the phenomena which steel and silver exhibit in the reflection of common light. As common light is similar to two equal pen- cils polarized +45° and —45°, and as steel brings two such pencils into a state of parallelism with the plane of reflexion, common light must therefore be wholly polarized in the plane of reflexion after eight reflexions. In like manner we see why the same effect is not. produced by silver, because, after eight reflexions, the two planes of the pencils are inclined 42°, or 2 x 21° 7, so as to form a partially polarized pencil. ‘The same results also furnish us with a method of comput- ing. the proportion of polarized light in any pencil of common light, reflected from metals at angles at which the restoration of the-elliptical polarized pencil is effected. In order to de- termine this proportion for steel after two reflexions at.'75°, we must consider that a pencil polarized +45° is restored by these two reflexions to light polarized —17°, and consequently a pencil polarized —45° to.light polarized +17. Hence a beam of common. light will consist, after two reflexions, of two pen- cils +17° and —17° of equal intensity, and consequently in the same state of partial polarization, as if common light had been reflected either at an angle of 45° or 68° from a capes of glass. Consequently in the formula* Q=1—2sin? 9, we have g = 17° and Q = 0.829. Hitherto we have considered elliptical polarization as pro- * See my paper “‘ On the Law of the Partial Polarization of Light by Reftexion,’’ supra, p. 76. 150 Dr Brewster on the Phenomena and Laws duced only at the maximum polarizing angle. It may be pro- duced, however, by a sufficient number of reflexions at any given angle either above or below the maximum polarizing angle, as appears from the following table, in which the reflexions are made from two parallel plates of steel. No of Reflexions from No of Reflexions at Steel at which Elliptic which the pencil is re- Polariz. is produced. stored to a single plane. Calculated. Observed. Angles of Incidence. 8, 9, 15, &. 6,12, 18, &. 8545 86 0 23, 74, 123, &c. 5, 10, 15, &c. 84 38 84 0 2, 6, 10, &. 4, 8, 12, &c. 83 30 = 82-20 14, 44, 74, &e. 3. Gp: Ga: eee 79 39 79 0 Ry? (OURS et 2; °4, 6, &c. 75 0 75 0O 13, 44, 71, &. 3, 6, 9, &. 68 53 —«GT 40 2,:016,9 00; o&e. 4, 8, 12, &c. 60 2 60 20 21, 71, 121, &c. 5, 10, 15, &c. 56 5 56 25° 3,:.9, 15, ,&c. 6, 12, 18, &c. 51 24 52.20 The numbers given in the third column are calculated by the following method. The relation of the preceding pheno- mena to the angle of maximum polarization is obvious; and — if we consider the nature of the formula, tan 9 — a we shall see that the angles at which the rectilineal polariza- tion of the primitive pencil is destroyed have a reference 'to the rotation which the reflecting surface produces in the plane of polarization. The angles indeed in the third column, at which similar effects are produced above and below 75°, are those at which g has equal values. This is a very important relation, and enables us to determine the phase P of the two inequal portions of oppositely polarized light, by the interfer- ence of which the elliptic polarization is produced. It‘ may be expressed by Pi=i2 R. But | R = 45° — 9, Hence P = 90° — 29, cos (i + 7’) tan 9 = cos Goa)” In this manner we obtain the following results. _. of Elliptic Polarization. 151 No Ber Angle of Angle of Inclination Rotation. of ni "ays ag meccienes of — ore. ee, RR: Phade, ot F 3 8 6 845 “30 0 '18’0 30 = } of 90 8349 8438 2615 1845 $7} = ¥ of 90 2 8230 8330 2230 2230 45 = § of 90 12 78 8° 7939 1115 $8345 673= § of 90 73.0 75 0 00 45 0 90 = } of 90 1 6625 6853 1115 3345 673= § of 90 2 5716 60 2 2220 2230 45 = } of 90 91 5317 56 5 2615 1845 387}= 7, of 90 S$ 48 38° 5124 30 0 15 0 | 80 = ¢ of 90 - In the results of the two preceding Tables, where the num- ber of reflexions is an integer, it is easily understood how an elliptically polarized ray begins to retrace its course, and re- cover its state of polarization in a single plane, by the same number of reflexions by which it lost it: but it is interesting to observe, when the number of reflexions is 14, 23, 34, that the ray must have acquired its elliptic polarization in the mid- dle of the second and third reflexion; that is, when it had reached its greatest depth within the metallic surface. It then begins to resume its state of polarization in a single plane, and recovers it at the end of 3, 5, and 7 reflexions. This station- ary point at which the retrograde effect commences, may be made to have its position at any dépth beneath the surface, by changing the angles of some of the reflexions, or by com- bining plates of metal of different polarizing powers. The same curious property is exhibited in total reflexions, as I have found that the circular polarization can be ne ced by 24, 35, &c. reflexions. Hitherto we have chiefly examined the phenomena when the reflexions, are performed either all above or all below the polarizing angle. We shall now proceed to the case when one reflexion is made on one side, and one on the other side of the maximum polarizing angle. When a ray polarized + 45° has been reflected once from steel at an angle of 85° or of 54°, it has acquired partially the state of elliptic polarization, and to such a degree that three 152 Dr Brewster on the Phenomena and Laws reflexions more at the same angle will complete the effect. But if the ray partially polarized elliptically by one reflexion. at 85° suffers a second reflexion at 54°, it does not acquire more elliptic polarization, but it retraces its course, and recovers its state of single polarization. The same phenomenon occurs at the following angles. _Angles of partial E1- Angles at which it reco- liptic polarization. | Valuesofg versits Polarization. Valuesof 1 Reflex. at 875° 936° 5’ 1 Reflex. at 41° 36° 11’ 85 27 28 54 20 0 80 12 12 68 12 36 at 5 24 72 5 59 75 0 0 75 0 0 It is obvious, by comparing these angles with those in the preceding ‘T'able, that they correspond, and are those at which equal phases or rotations are produced. The effect of two reflexions, at angles of equal phase, upon the inclination I of the plane of polarization is shown in the following Table. Inclination I of the Plane _ of Polarization. Observed. Calculated. 1 Reflex. at 90° and J at 0° 45° 45° 0’ 871 Al — 30. 0.— 85 54 26 26 5 80 68 19 20° 8 77 12. 18 7-2 75 75 yal 17.0 The last eolumn of the table.is calculated by the ane I = tan 9 (45°—~ 7’) + %, i being 17°, or the inclination after two reflexions at the maxi- mum polarizing angle. In the preceding inquiry we have considered only the phe- nomena when the consecutive reflexions are performed in coin- cident planes. ‘The investigation becomes more troublesome, and the results more interesting when the plane of the second reflexion is presented in every different azimuth to the ray ’ that is either wholly: or partially elliptically polarized’ by the first reflexion. of Elliptic Polarization- 153 Let a pencil be elliptically polarized by one reflexion from steel at ‘75°, and let the azimuths be reckoned from the plane of this reflexion. We have already seen that a second reflex- ion at ‘75° in azim. 0° and 180° restores the pencil to a single plane of polarization ; but if we turn the plane‘ of the second reflexion into axim. 45° or 225°, we shall find that the angle of restoration is no longer 75°, but ‘78°. At azim. 90° and 270° it is again 75°, and in azim. 135° and 315° it is only 68°, having varied from 68° to 78°. The following table shows the observed and calculated angles of ‘restoration in different azimuths. Azimuths from Plane Angles of Restora- Complement of Angles of Re- of first Reflexion. tion from Steel. storation or Elliptical Radii. Observed. Calculated. © and 180 75 15 14.9 223 2021 77 13 12.7 45 225 78 12 12 © O7R«') 247k - 774 cs dae Rinbomahes b Cy 90 270 75 15 14.9 1123. ° 292)» 70°: 20 19 135 315 68 QQ 22 157}: 3374: 70 20° 19 180. 360 75 “15 14.9 The radii in the two last columns are obviously those of a curve approaching to an ellipse whose major and minor axes are situated, the one 45° to the right, andthe other 45° to the left of the plane of the first reflexion. ‘The major semiaxis is 22° and the minor 12°., Hence. calling # the variable: radius of the ellipse, a the greater, and b the lesser semiaxis, and 6 the azimuth, reckoned from the lesser axis, in which the radius # is wanted, we shall have ab = Ja? cos? 0 + 6? sin 2. 4° When 4 — 45°, 135°, &c. sin? 4 cos? ¢ — } and ab 7 a? + 5 6? ': By calculating the values of a corresponding to the azimuths in the table, we obtain the numbers in the Jast column, which v x 154 Dr Brewster on the Phenomena and Laws are so near the observed numbers as to leave no doubt that an ellipse represents the observations. If we perform the same experiments with a plate of silyer at ‘73°, we shall observe, with surprise, that the angle of re- storation is the same in all azimuths, that is, that the ellipse has merged into the circle. There is a slight deviation mdeed, just° sufficient to show that the circle is slightly oval, but I could not measure the amount of it. This result arises from the elliptical polarization of. sien being very nearly circular. If we call 6 the angle of restora- tion after two reflexions, the ratio of a to 6, the major and minor axes of the StS may be thus expressed : : 6 = sin 28: rad. In steel, where Sn = 17° and 28 = 34°, we have a:6 = 0.559: 1 = 10: 211, differing very little from 10: 22 the actual ratio. In silver, where 8 — 39° 48”, a:b = 0.9835: 1—17:173. In circular polarization, where B= 45°; @: b ae which gives a circle. In rectilineal polarization, where 8 = 0,a:6 = 0: 1, which gives a straight line. It now becomes an interesting subject of inquiry to ascertain the form and position of the ellipse, when the angle of inci- dence on the first plate exceeds or falls below. the maximum polarizing angle. , Aa The following experiments were made with silver at angles of incidence of 80° and 68°, the maximum polarizing angle being 73°. Siiver. —Angle of Incidence on First Plate 80°. Azimuth Complement of Angle of Azimuth Complement of Angle of to Right. Restoration by 2d Plate. to Left. | Restoration by 2d Plate. Vu ° 28° Q' 0° 28° 2 113 26 35 11} 24 40 224 25 20 224 21 6 333 21 13 33% 16 40 45 18 20 45 14 35 564 14 20 564 11 10 67} Fo ee 673 10 0 783 10:15) 78 10 0 90 10 O 90 10 0O ¥ 4 ‘of Elliptic Polarization. 155 Sinrver.—Angle of Incidence on First Plate 68°. 0° 13° 0° 13° 11} 14 114 13 221 153 Q91 134 33} 16 $32 14 45 17 45 144 56} 19 561°: 15} 673 20 674 163 785 20 783 18 90 20 90 20 ~ In the first of these sets of experiments, the semiaxes of the ellipse are as 10° to 28°, and its major axis is in azim. 0° and 180° or in the plane of the first reflexion. In the second series the ratio of the semiaxes is as 13° to 20°, and the major axis is in azim. 90° and 270°, or perpendi- cular to the plane of the first reflexion; but in both series there is a want of symmetry in the curve to the right of azim. 0° where it bulges out, showing that in both series the greater axis is a little to the right of azim. 0°. Hence it appears, that in silver, whose elliptic polarization is nearly circular, the ellipse which regulates the angles of re- storation has its greater axis in the plane of the first reflexion for all angles greater than 73°, the maximum polarizing angle ; and from a circle it increases in ellipticity till at the limit of 90° the lesser semiaxis is 0°, and the greater 90°, and it be- comes a straight line. For angles above 73° the ellipse has its greater axis perpendicular to the plane of reflexion, and gra- dually increases in ellipticity from the circle till at the limit of 0° its lesser semiaxis is 0°, and its greater 90°; when it becomes a straight line. The peculiar character of elliptic polarization shows itself in another manner, and with peculiar interest, in the variable po- sition of the ellipses which regulate the angles of restoration upon steel. We have already seen that the curve which is circular in silver at the maximum polarizing angle, is in steel an ellipse whose semiaxes are as 12° to 22°, the greater axes being in- clined 45° to the right of azim. 0°. r 156 Dr Brewster om the Phenomena and Laws The following table will show how the effect varies at angles of incidences above and below the polarizing angle SrrEL.—Angle of Incidence 80°. Complement of Angle Complement of Angle Azimuth to — of Restoration by Azimuth to of Restoration by Right. Second Plate. T eft. Second Plate. 0° 23° O:° 23° 113 25 11: 20 221 26 22t 16! 333 24 333 13 45 205 45 11} 56% 18 56} 10 671 15! 67 gt 783 if 783 98 90 1 90 10 StzeE.L.—Angle of Incidence 68°. - Complement of Angle Complement of Angle Azimuth to _— of Restoration by Azimuth to. of Restoration by — Right. Second Plate: Left. - Second Plate. | poms 11° 0° 1}° 124 24 11} 10 225). - 243 22% 9 33% 255 333 9 45 265. 45 11 56} 254 56} 15 675 20 675. 18 78% 21 78% 20 90. 22 90 22 By comparing ‘these results with those obtained from steel at ‘75°, and with the observations already made on the passage of the ellipse into a straight line, the following results may be deduced: Angle of Ratio of Incid, on Semiaxes first Steel ofthe Character of the Position of the greater Plate. _. Ellipse. Ellipse. Axis of the Ellipse. 0° «60 *: 90° Straight line Azim. 90° and 270°. 68 9 : 26° Ellipse” —— betw. 45" and'56° to Rv 75. 1 222° Ellipse — - = 6) 46% to Ri 80 %4 :26 Ellipse ate lo Leh odie Sag etl 90 90 Straight line - ¢) of Elliptic. Polarization. 157 Hence it is obvious that the major axis of the ellipse is 45° + ¢ RB to the right of 0° of azimuth, 9 being computed from the formula ° ; _ cos (2 + 7 Ader in) = SG There is a deviation at the incidence of 68° and 80° of some amount, but still it is scarcely without the limits of the errors of observations when common light is used. In strong lights the coincidence will doubtless be more perfect. The best method of determining the position of the major axis, is to place the second plate at such an angle to the ray received from the first, that it may exceed by two or three degrees the angle of restoration in azim. 0°. Hence if we turn the second plate round the ray into all azimuths from 0° to 90° in the right hand quadrant where the greater axis lies, it must come into two azimuths where the restoration takes place at the same inéidence. ‘The complements of these two angles of incidence will be equal radii of the ellipse, and con- sequently the azimuth which bisects the two azimuths in question, will be that of the major axis of the ellipse. By in- creasing the angle of incidence on the second plate, other two azimuths containing equal radii of the ellipse will in like man- ner be found ; and we might, if necessary, at least obtain an angle of incidence where the two radu coincided with the greater axis. ~The position of the ellipse bemg thus given, we may deter- mine it for all angles of incidence. Calling # the angle of in- cidence on the first plate, then we shall have four points in the ellipse as follows. The radii in azim. 90° and 270° are always 90°—, and the radius in azim. 0° and 180° is the complement of the angle of incidence at which ¢ in the last equation has the same value as at the angle w. Hence the form of the ellipse is also given. In these experiments the polarization of the primitive ray has always been + 45°.. When this plane varies its position, that of the restored ray also changes, as we have already shown; but it remains to be seen what change takes place in the angles of restoration. At all angles of incidence, a varia- tion in the plane of primitive polarization does not alter the 158 Dr Brewster. on the Phenomena and Laws angles of restoration or the corresponding radii of the ellipse in azim. 0°, 90°, 180° and 270°; but at all intermediate azi- muths of the second plate the angles of restoration diminish while the primitive plane varies from 45° to 0°, and increase when it varies from 45° to 90°. The following experiments show the progress of the change when the azimuths of the se- eon reflexion are + a5: and — 45°, STEEL. Inclination of Azimuth of Second Re- Azimuth of Second Re- - Plane of prim. flexiow + 45° to Right. . flexion — 55° to Left. Polarization. Observed. Calculated. Observed. Calculated. 0° 0° 0° 0’ ag o° 0’ 5. 2 2 4 2 r" 6 10 4 3 46 3} g')'8 15 6 5 43 44 sa 20 83 7 50 6 4 14° 25 11 9 54 6 5 26 30 13 12 11 7 6 43, 35 15 14 40 8 8 6 40 18 17. 25 93 9 41. 4.5 203 20 30 Ela 11 30 These observations are represented by the formula, tan ¢ =. tan a. tan a; @ being the angle of restoration when #, the in-. clination of the plane of primitive polarization, is 45°. I have not given the values of 4 from 45° to 90°, because it. is difficult to ascertain even in strong lights when the evanes- cence commences. At 90° the action of the first plate is 0, so that at this limit the angle of restoration is the angle at which’ the elliptic polarization is no longer visible, from the smallness, of the angle of incidence, an angle which varies with the inten- sity of the light employed Hitherto we have attended only to the phenomena produced. by two similar metals. When the metals are dissimilar, the, one silver and the other steel, I found that at the mean maxi- mum polarizing angle of 74°, the inclination of the plane of the restored ray was 28° 30’. But 28° 24 = Sea Me so that the inclination is an arithmetical mean between that of silver and that of steel. By four reflexions at 74° the inclination was reduced to 14°, while by four reflexions at about 83° and 58° of Elliptic Polarization. 159 28° 30' + 14° the inclination was 21 }°, nearly equal to ——5—— according to the formula i in page 297- By thus combining dissimilar metals, we may produce elliptic polarization of all degrees of intensity intermediate between those produced by similar metals. As the circular polarization of total reflexion is the limiting case of elliptical polarization, it becomes important to establish by experiment their intimate connection and almost perfect si- milarity. Upon combining metallic and total reflexions this was at once evident; and I found in_ general that circular polarization of any intensity, as produced by either one or more reflexions from glass, may always be restored to rectilineal po- larization by one or more metallic reflexions, provided the lat- ter are all made at angles less than the maximum polarizing angle, and that the two classes of reflexions are performed in coincident planes- As this takes place throughout the whole range of total re- flexion from 41° to 90°, it follows that total differs from metal- lic reflexion in its having two opposite kinds of circular pola- rization, like the two opposite kinds of elliptical polarization which take piace on each side of the maximum polarizing angle of metals. But notwithstanding this, the circular like the elliptic polarization has a maximum at about 50°, declining rapidly to zero at 41°, and on the other side slowly to zero at 90° of incidence. When one reflexion from steel was combined with two total reflexions from glass at 545°, the inclination of the plane of the restored ray was 30%", an arithmetical mean between 45° that of total reflexion, and 17° that of steel, for Batt =$1°. With silver the inclination was 424°, and we 4 30 = 42° 24’. If we make the metallic reflector receive the circularly po- larized ray in every azimuth, we shall find that in azimuth 90° the circular polarization is compensated by a metallic reflexion above 80°. As the azimuth diminishes to 0°, this angle of compensation diminishes also, passes through 75° in the case of steel, and diminishes to a number depending on the angle of incidence at which the total reflexion is made. | We are thus 160 Dr Brewster on the Phenomena and Laws enabled to study the phenomena of circular polarization by the aid of metals, and to obtain results at which it would be ex- ceedingly difficult, if not impossible, to arrive by any other method. ‘This subject, however, presents too wide a field to be treated thus incidentally. | Seer. II] —On the complementary colours produced by succes- sive reflexions from the polished surfaces of metals. ‘T have already given a general account of the phenomena of colour produced by ‘successive reflexions ; and I have shown that the tints thus produced are by no means the same as those of crystallized plates, as they do not rise in the scale by succes- sive reflexions. In my early experiments on total and metallic reflexions, I regarded the two classes of phenomena as exactly the same, mutatis mutandis ; and in communicating these results to Dr Young, I pointed out their coincidence with his theoretical views. Dr Young noticed these experiments in the following manner.* “ Dr Brewster has also shown that the total reflexion of light within a denser medium, and the brilliant reflexion at the sur- faces of some of the metals, are capable of exhibiting some of the appearances of colour as if the light concerned were divid- ed into two portions, the one partially reflected in the first in- stance, the other beginning to be refracted, and caused to re- turn by the continued operation of the same power. ‘The ori- ginal interval appears to be extremely minute, but is capable of being increased by a repetition of similar reflexions as well as obliquity of incidence.” In a letter which I received from this eminent philosopher, dated March 25th, 1816, he thus modifies an objection which he had previously made to my opinion, that the phenomena were owing to the interference of the light which had entered the surface with that which had suffered partial reflexion. “‘ The light which you suppose to have entered a little way into a reflecting surface, in the case of total reflexion, is sin- gularly circumstanced with regard to the objection I mention- ed in my last letter. I did not like the idea of supposing a * Art. Caromarics, Supp. Encyc. Brit. p. 157. of Elliptic Polarization. 161 surface of any kind to contain a finite space ; but, in fact, if your theory should be confirmed, this objection might be greatly ¢ diminished. by the consideration, that the thickness of the surface would still be like an infinitesimal of a different order from the. interval corresponding to its apparent effect, being the versed sine of a curve of which that small interval i ig the are, and possibly i in a circle ‘of curvature not very minute.” In continuing my experiments on this subject, I found that the colours of total reflexion did not rise in the scale by suc- cessive reflexions; and as they modified the tints of erystalliz- ed bodies by adding to, or subtracting from, them a given por- tion of a tint, I announced in the end of 1816, in the Journal of the Royal Institution, that I had discovered ‘a new species of moveable polarization, in which the complementary tints never rise above the white (the blueish white,) of the first or- der, by the successive application of the polarizing influence.’ i I determined, experimentally, the angles at which this tint was successively produced and destroyed, and thus discovered some of the leading properties of total reflexion, before, I believe, . M. Fresnel had made any experiments on the subject. It was he, however, who ascertained that this new species of polariza- tion was circular polarization ; and it is impossible to speak too highly of the ingenuity and talent which he exhibited in that difficult i inquiry. This view of the phenomena of total reflexion unsettled the opinions which I had entertained respecting the action of me- tals, and I was thus led to revise and extend the unpublished experiments which I had made on the subject. In order to ascertain the effect of a single metallic surface, | I took a crystallized plate of glass whose central tint was the bluish white of the first order, and positive like sulphate of | lime. ‘This tint varied from a quarter of a tint in value down to zero. The primitive ray was polarized + 45°, and the plate of steel was horizontal. This ray was received at an in- cidence near 90°, and the principal section. of the analysing prism was in the plane + 45°, while the length of the plate of glass was fixed perpendicular to the plane + 45°, or to the principal section of the prism, so as to move along with it. * Journ. Roy. Inst. vol. iii. p. 213. NEW SERIES, VOL. IV. NO. I, JAN- 1831. L 162 Dr Brewster on the Phenomena and Laws At an incidence of 88° the metallic action destroyed the ac- tion of the equivalent crystallized plate when the section of the analysing prism was turned from + 45° to + 38°. At an incidenée of 831° the same effect was produced when the same section was turned into the plane + 221. And at an angle of 75°, viz. the maximum poletaiaty angle, the compensation took place when the axis of the -erystal had moved round 45°. In like manner, at an atiglé of 60° the compensation took place when the axis of the crystal was turned todd 45° + 227°, or — 227° ; and, - At an angle of inéidénée of 40° the compensation was effect- ed when the axis of the crystal had turned round 45° + 37°; or into the plane — 37°. The same results are obtained when the light falls oh the metal before it passes through the crystal: Hence it follows, that at the maximum polarizing angle the effect of the equivalent crystal placed i in aziniuth 45° to the plane of primitive polarization, 1 is ‘CoMipensaterk by the action compensation is effected in azimuths less thie 45°; and, at less angles of incidence, in azimuths greater thant 45. When the reflexion from the metal is made in a plane pet- pendicular to the meridian, the opposite effect is produced. The angles at which the compensation takes place in the preceding experiments are obviously such, that calling R the angle of rotation of the axis of the crystal, it has always to i the angle of incidence the same relation as if the formula, tan (45° — R) = — pt a3 to Hence we are led to the important conclusion, that the pen- cil which enters the metal follows the changes of polarization of the partially reflected pencil, which is regulated by the same law as in transparent bodies. It now became interesting to examine the effect produced by the joint action of. the metal, and an equivalent crystal, in changing the plane of polarization of the restored ray. The following are the results with different metals at the maximum polarizing angle. of Elliptic Polarization. 163 Metals. Position of the Plane Rotation me 4 of Polarization. effected. Silver (pure) + 42° 3° Copper - + 363 - 83 | Mercury -.— - + 35 - 10 Platina - + 34 - 11 _ Speculum metal +32 = 13 Steel Lee - - + 804 - 14% Lead - - + 26 - 19 Galzena - ae Yi - Q73 These metals follow the same order in their action pon the plane of polarization that they hold in the table in page 144, though in reference to the rotation actually produced in both cases the order is inverted. _ The preceding table points out in a very instructive man- ner the difference between the action of a metallic surface and an equivalent crystallized film. When two metallic surfaces act together, the plane of ‘polarization of the restored ray is invariably thrown beyond the plane of reflexion; whereas in the combination of a crystallized film with a metallic surface, the same plane never reaches the plane of reflexion, the plane having always a negative position in the former case, and a positive one in the latter: Thus m two reflexions from silver at 73°, the primitive ray polarized + 45° has its plane of po- larization changed into — 39° 48’, whereas in the combination of one reflexion from silver with the crystallized film, the plane is changed only into + 42° In order to determine the law of the metallic action at diffe- rent incidences and with different numbers of reflexions, I in- terposed. between the eye and the metal, which was silver, a plate of chlearcous spar, which exhibited its uniaxal system of rings. The influence of the metal in modifying the rings was a maximum at’73°, exactly as if they had keen crossed bya positive crystalline film which polarized a quarter of a tint, or the pale blueish white of the first order, and whose axes was situated im a plane + 45°, or that which bisects the planes of the two pencils oppositely polarized by the metal. The influence of the metal, or the tint which it polarizes, diminishes gradually 164 Dr Brewster on the Phenomena and Laws, &e. from 73° to 90°, where it vanishes, and consequently where the rings recover their symmetry and their tints. At this limit the position of the axis of the equivalent film is a line still bisecting: the planes of the two oppositely polarized pen- cils. At incidences from 73° to 0° the opposite effect takes place, the rings recovering their symmetry at 0°, and the po- sition of the aie of the equivalent film being now vertical, and bisecting the planes of the two oppositely polarized pencils. At all intermediate angles of incidence the axis has inter- mediate positions ; ; and calling A the inclination of the axis to the plane of reflexion, we shall have A = 9 + 45°, 9 being positive or + from 90° tu 73°, and negative or — from 72° to 0°. The intensity of the metallic tint, so to speak, or of the posi- tive equivalent plate T, will be P. 2R. 42-9 T = 4 90 =360,— =( 180, Hence we see the error of the proposition hitherto maintain-_. ed, that an increase of incidence, reckoning from the perpendi- cular, produces the same effect as an increase of thickness in thin crystallized plates. When the rings are combined with two reflexions at '73° in silver, or '75° in steel, they do not suffer the slightest change, the principal section of the prism being placed in the plane — 39° 48’ with silver, and —17° with steel. By two reflexions, however, between 73° or 75° and 90°, an effect is produced on the rings which increases gradually in silver from 73° to 82° 30’, and diminishes from 82° 30’ to 90°.. At 82° 30’ the effect is the same as after a single reflexion at 73°; for since four reflexions at 82°'30’ restore the elliptically polarized ray, two reflexions at the same angle must have produced complete ellip- “tical polarization, At angles between 82° 30’ and 90° the pencil is only partially polarized elliptically ; whereas from 82° 30’ to 73° the light has been more than elliptically polar- ized, the restoration of it having been begun during the second reflexion. Hence, in order to determine the phase for any angle between 82° 30/ and 90°, we must take the sum of the phases for each reflexion, or 2 P; whereas between 82° 30’ Mr Grosmann’s account, &e. ) 165 ‘and 7° we must take the excess of the sum of the two phases above 90° or 90°— 2P. In both cases the pencil has suffer- eda partial elliptic polarization ;—in the former, from the sum of the actions of the two reflexions, and im the latter, from their unbalanced actions. he very same effects take. place between 73° and 57° 16/, the other maximum, as between 73 ‘and 82)°; and between 57° 16’ and. 90°, 9/88 between 821i and 90°. ; In the case of three reflexions there are two points or nodes of restoration, viz. 78° 8’ and 66° 35’, the maximum being at 85° 6/, 73°, and 48° 38’, at each of which points the. phase is 90°. At 73° the second reflexion restores the ray elliptically polarized by the first reflexion, and the third reflexion again produces elliptic polarization. At 85° 6’ and 48° 38, six re- - flexions produce a restoration of the pencil, and consequently three reflexions must have polarized the pencil elliptically with a phase of 90°. From 85° 6’ to 90°, and from 48° 38’ to 0°, the pencil has been only partially elliptically polarized, and the ‘phase at any: angle between these will be 3 P. At any angle between 48° 38’ and 85° 6’, the phase will be 2x 90— 3 P. In general, calling m the number of reflexions, the phase between 90° and the nearest maximum, and between 0° and the nearest maximum, will be n P, while at all other angles of incidence it will be (x —1 X 90) —nP. (To be concluded in next Number. ) Arr. XV.— Account of a remarkable Water-spout accompa- nied with a Lwminous Meteor. By M. Grosmann. Arrtera drought which lasted here for many weeks, we were refreshed by an agreeable rain which fell on the 16th of June. It continued at intervals on the 17th and 18th. From the 20th to the 24th, the thermometer had_.risen by a constant N. EF wind to 19—25 (Réaumur.). ‘Though on the evening of the 24th the barometer being as-high as 27 inches 9.1 lines -a'slight storm of »rain greatly cooled the air, it had again be- 166 Mr vehi s Account of a remarkable a. comevery hot on 25th, both beforeand after a shower ta fallen at eleven o’clock in the morning. The ground was therefore, so to speak, on fire. ‘he barometer fell to 27 inches, 7.8 lines About two o’clock in the afternoon, one mile above Treves to the E. N. E. of Ruwer and of Pfalzel, at about 20° above the horizon, a phenomenon took place which struck with astonish- ment, and for half an hour caused a deal of uneasiness in, a number of men who were occupied out of doors. The sky after the rain was over was still cloudy, when all at once, from the middle of a black cloud which rose from the E. N. E. , a luminous mass began to move in a contrary direc- tion, and to tear itself away violently. The cloud soon took the shape of a chimney towards the top, from which escaped a whitish gray smoke, mixed here and there with jets of flame, and raising itself by several apertures with much force, as se- veral witnesses testified, as if it had been driven with celerity by many blasts. The meteor had arrived above the Vines of Disburg, and opposite Ruwer, when at some distance more to the S. upon the right bank of the Moselle, quite in contact with the ground, ‘a new meteor as it seemed to be to many individuals, appeared in a terrific manner. It dispersed some masses of coals which were heaped round a tree, overthrew a man who was working at a lime-kiln, and threw itself across the Moselle with formidable noise, as if a great many stones were crashing against each other The water.rose in a lofty column. Rolling along on the ground with the same noise, this last meteor went :to:the Moselle crossing the:fields of Pfalzel, leay- ing evident traces of ‘its route in zigzag lines across the fields of corn and pulse. Parts of the pulse was entirely destroyed, another part was laid and damaged, and the rest raised rand carried far away by the wind. Several women, near whom the meteor passed, fainted, others fled screaming and hid themselves; all the fields seemed ‘on fire. Two labourers who were mounted on a tree observed the meteor in its whole progress. Another had the courage to follow it, and this was easily done at an ordinary foot pace. accompanied with a Luminous Meteor. 167 But in one of its zigzags which it described the meteor sudden- ly surrounded him. He felt sometimes drawn for ward, some- times violently lifted up. He lay down, resting himself firmly on the ground with his tools, but he was still thrown over. The whirlwind then left him and continued its course. He does not remember any particular effect either upon his organs of taste or of smell, but there was a deafening noise. fle af- firms that it had two currents, one of which raised itself obli- quely, carrying with it straws and other light bodies; the other took an opposite direction. The route which the meteor had traced in crossing the fields, was, according to different accounts, from 10 to 18 paces wide by 2500 long. Its form was nearly conical; its colour was sometimes whitish grey or yellow, sometimes dull brown, but more frequently the colour of fire. The first meteor was in the air above this one, nearly parallel in advance towards the N. It presented during about eighteen minutes, a great mass of greyish white, which seemed often to vomit the red smoke of flame ; and which, when seen at the distance of about half a mile, was in the form of a serpent 140 feet long, the head of which was towards the N.N. E.; and the tail m the opposite direction. In eight or ten minutes, the tail had suffered a change in de- scending. Atthe instant when it was near touching the head, the whole phenomenon disappeared ; and at the same time also the inferior meteor, without, as we are assured by an eye witness, the slightest explosion. Buta smell of sulphur, very offensive, distributed itself over the whole country. Almost immediately after, a storm burst upon the woods situated to the N. N. W. of the place where the meteor appeared, and it was attended by a hail shower, the stones of which were of immense magnitude. The sun did not appear all this while, and there was no wind. ‘The large meteor was seen at Gutweiler, Cassel, and other places, and also at Treves. It appears to have descended from the heights of Hochwald —Schweigger’s Veherbuch der Chimie, &c. Trevis, June 30th 1830. 168 Dr Noggerath on an accident from compression of the Air, Arr. XVI.—An account of a remarkable accident which oe- curred in a mine of Bovey Coxl, in consequence of the com- pression of the Air. By the Inspector, Dr Proressor Néc- GERATH. * a. Ix order to understand correctly the following account of. the accident which occurred at the pit of Turnick in the territory of Cologne, it. is necessary to premise a few words concerning the subterraneous position of the coal pits, and the manner of working them which for some time has prevailed in this region. ‘The coal business is of great importance in this district, and several hundred workmen are employed in it. Some pretty high ridges of hills, which arise in the Sool Godesberg, extend. more than half a league from Bonn on the Rhine, to the region of Bergheim on the road from Cologne towards Aachen, where they end in a plain, constituting the main locality of the ternary formation of Bovey coal. This coal is commonly covered with layers of clay not very compact ; and over the clay to the surface of the ground, is a deposit of coarse sand and rubbish, washed from the hills. Where this covering is thick and strong, in order to obtain the coal to ad- vantage, the mining is performed by a process, or rather a par- ticular kind of excavation, which in our region is termed ¢wmel- bau. 'The parts of the tumelbau are shafts, passages, and arch- ed cavities. 'The whole mine is commonly sunk to one base, namely, just above the level where water would naturally stand. But when, by its natural situation, or by artificial draining, the mine is carried very deep, and the stratum of coal is thick and extensive, a second tumelbau is made under the other, after the former has become exhausted. In the mine there are two apertures, one of them for the passage to and from it, and the other, called the wind shaft, for ventilation. These two shafts at the bottom are united by a passage, connect- ing them at right angles. Upon this passage the mining is be- gun by forming a ¢wmmel, which is arched above like a bee-hive, and its bottom is continued on the level of the passage between the two shafts. A tummel is commonly from three to six fa- thoms in diameter, and from two to five in height. The coal * Jahrbuch der Chem. und Phys. in a Mine of Bovey Coal. 169 itself serves to support the highest part of the tummel, because, | by the pressure of its sides it settles of itself to a certain extent, the excavation still preserving its arched form. When the tum- mel is carried so high as to reach the top of the layer of coal, or ‘the level of the tummel is itself reached by a second mine that has been sunk under it, by degrees it commonly breaks and be- ‘comes filled, by which means, the walls or parts subject to the “pressure, are again brought together and consolidated. “By the ‘filling up of the tummel, many funnel-shaped apertures on the ‘surface are formed. A second or third tummel can at any time ‘be formed upon a passage by removing the surrounding coal, or hy making a new excavation ; and in the present instance, upon the right and left of the main excavation, and at the shafts, new ‘passages had been formed, and new tummels had appeared, so ‘that the mine was continually enlarging, and receding farther backwards. Finally, near the wind shaft, and likewise by the main tummel, pillars were erected to make the works as strong as possible. A new tummel had been sunk below the passage “between the two shafts, and the shafts themselves were continued . down to the level of its base, and a passage formed for connect- ‘ing them. The old tummel did not fill again as is common after a new one is formed below, because from one-third to one- fifth of the superincumbent coal had been left for support, in consequence of the extreme caution of the workmen. But it was difficult to secure it altogether, as the coal was very light in some places, and the timber was small as a matter of economy, ‘in consequence of the moderate profits of the mine. The accident occurred in the tummelbau of Botterbroicher, Therchengrube, near Turnick, Feb. 7, 1826. ‘There were in the mine, Ist, John Weber, contractor, who was killed; 2d, Martin Pohl, coal cutter, who had his sight slightly injured, besides a superficial bruise of the thigh; 3d, Jacob Brewer, coal porter, who had a shoulder dislocated, and a severe contu- sion of the left thigh. Without the mine, though near a shaft, were in waiting two windlass turners, John Bieck and Hilger Zimmermann. At 7 o'clock, a. m. as the workmen were going into the mine where they had worked the day before, a pressure was per- ceived, and in apprehension of the falling in of the tummel, 170 Dr Noggerath on an accident from compression of the Air, they took the precaution of employing themselves upon the coal near its entrance. About 9 o'clock, the pressure had sen- sibly increased, and some large pieces of the clayey stratum of the arch fellin. Weber the contractor heard the crash, and ran to those.who were in the pit. He had the tummel searched externally and internally, and thought it not proper for the workmen to go immediately to their business, but that they should first eat their breakfast, and if in the meantime, there should be another break, they might quit their work. Upon _ this, Weber set.out to brace the pit, the workmen remaining seated at their breakfast in the wind shaft, near the passage to the tummel. Weber had been gone but a few moments, and had not probably reached the middle of the ascent of the shaft, when the tummel suddenly fell in, and the rush of the air was so terrible that Pohl, who was five fathoms within the. wind- shaft, and Brewer, who was in another passage, were thrown down. Pohl recovered himself as he was lying upon the wind- shaft ; aud upon regaining his senses, looked after his compa- nion, whom she found senseless in the main passage. After Brewer had recovered so as to come to his reason, they found Weber the contractor near them, apparently lifeless. Upon calling, Bieck came to their assistance. -Brewer was drawn out by means of a rope, and the body of Weber was brought out in the same manner. Pohl was able to climb out, without as- sistance. Bieck and Zimmermann state, that after Weber had left them, Bieck called and inquired whether they should take their breakfast within the shaft? After receiving an answer, they went about ten paces from the mouth of the shaft to the hut, to eat their breakfast. In less,than a quarter of an hour an alarm- ing noise was heard. The brick roof of the hut, that was built over the entrance of the mine, was blown into atoms, and an entire ladder was thrown out of the shaft, which fell upon the hut of the other shaft, that still remained standing. ‘The hats of those who were within the mine were found at the distance of twenty paces without from the mouth of the shaft, as also two iron hooks with which the ladder had been fastened, were picked up near the shaft, one of them broken short,,the other torn out of the timber and twisted. Upon examining the shaft, | ina Mine of Bovey Coal. 171 it was found, that by the powerful dislodgement of the ladder, the timber of the shaft had been much damaged. This is a very strange ‘and singular accident of its kind, which could arise only from the violent compression of the air in the cavity of the tummel, at the moment when it was filled by the simultaneous fall of the materials of the arch. The “great strength of the strata, combined with the circumstances, that there was, directly over the pit, a very firm clayey roof, was the cause of there being given to the tummel (though it was very ill judged,) uncommonly large dimensions ; for by the report of the coal-cutters, it was twelve fathoms in diameter, and four and a half in height. To increase the force of the rush of air, another circumstance greatly contributed. In late- ‘ly fitting up the mine, two apertures only were retained, the ‘wind-shaft and the passage for conveyance. As the tummel fell, the whole mass of air was forced out of one passage only, the pressure being directed to this, because during the cold -weather the wind-shaft had been stopped at its mouth. When we consider the amazing force with which the ladder was carried out of the shaft, and the other circumstances ‘testi- fied by the workmen, it is most probable that Weber, who was on the ladder as the tummel fell in, and wore a long linen frock, was lifted up by it.so high, that the distance of the fall caused his death. The medical examination of the corpse of Weber, discovered numerous fractures. ‘The fourth, fifth, and sixth ribs of the left side, and the heads of others were broken, and driven into the cavity of the chest. The pericardrum on the left side from above downwards was ruptured, as was also the right cavity . of the breast. The left lobe of the lungs exhibited several Ja- cerations, and was crushed into a confused mass. 172 Analysis of Scientific Books and Memoirs. Art. XVII.—ANALYSIS OF SCIENTIFIC BOOKS AND “ME- '. .MOIRS. Principles of Geology, being an attempt to explain the goo changes of the Earth's Surface by reference to causes now in operation. By Cnartzs’ - Lyet, Esq. F. R. S. Foreign Secretary to the Geological Society. In two volumes. Vol. I. London, 1830. Pp. xv. and 511.—Continued from Vol. III. p. 349. Beroxe proceeding to quote from the remaining portion of Mr Lyell’s yo- lume, we propose to dwell for a moment on his theory of the Pe of temperature in the course of the great geological period, which we had just noticed in last number. He proves, as may easily be done, the influ- ence of land, especially high land, in modifying the mean temperature of the globe, according asit is in higher or lower latitudes than the isothermal line representing that mean temperature. He then proposes the elevation "of land in the arctic regions, since the earliest epochs of geological records as afit explanation of the admitted refrigeration of the crust of the earth; but in applying this theory to observed facts, his inductions appear not so legiti- “mate, nor is a sufficiently precise picture drawn of the testimony of the strata. Our first objection is this ; while Mr Lyell admits the efficiency of inter- tropical land in ameliorating the climate, * as well as of arctic land, in dete- riorating it, in giving full weight to every indication he can obtain of the actual effect of the latter, he sinks in total neglect, operations, perhaps ana- logous in nature, though precisely the reverse in effect which have occur- red in the former. ‘‘ Our information,” he says, ‘is at present limited to lati- tudes north of the tropic of Cancer, and we can only hope, therefore, to point out that the condition of the earth, so far as relates to our temperate and arctic zones, was such, as the theory before offered, would have led us to anticipate.” + It will not do to say, that, in accordance with the “ uni- formity” system, we are to suppose the ratio of land and water on the globe a constant quantity ; that would be still more illogical than the supposed conjecture of the New Zealander, which Mr Lyell ridicules, that there is no more land in the northern than the southern hemispliere ; besides the chances are, that the exchange of land would have taken place from the antarctic to the arctic regions, and not from the equator. While, therefore, Mr Lyell is boldly drawing his conclusions from appearances in higher latitudes, his argument is wholly inept, unless he can at the same time prove that changes similar to those he describes were not going on in intertropical regions, for were they doing so, as by all analogy we may suppose, the two results being opposed, their effect would be null or trif- ling. It therefore appears to us, that, by pointing out to the reader what alone served his theory, and by making him neglect under the plea of want “P07 + P. 126. Mr Lyell’s Principles of Geology. » 1% of information, what was equally essential to its validity, the author has commenced his argument with a total flaw in the premises. But farther, the assertion is far too vague, that a “ glance at’the best: geological maps now constructed of the various countries in the northern hemisphere, whether in North America or Europe, will satisfy the inquirer that the greater part of the land has been raised from the deep, either be: tween the period of the deposition of the chalk and that of the strata termed tertiary, or at subsequent periods, during which the various tertiary ps were formed in succession. For, as the secondary rocks from the lias to the chalk inclusive, are, with a few unimportant exceptions, marine, it follows, that every district now .occupied by them has been converted into land since they originated.” P. 134, 135. Now in this argument, Mr Lyell seems to pass over the important fact, that it is only land elevated in a higher latitude, than the parallel repre- senting the mean temperature, (not of the surface of the globe but) of the quadrantal are of the meridian, which could by his own theory deteriorate the climate. It is therefore most of all in the extreme north of the continents and in the polar regions that we must look for those modern rocks which Mr Lyell considers the test of recent elevation. Under this point of view, the fact, we believe, is calculated to produce different results. We do not pretend to anything like accurate knowledge of the formations of the higher latitudes, but it is strikingly remarkable that in the voyages of © Parry and other modern navigators, rocks later than the coal formation are almost wholly awanting, except in some parts of West Greenland. This may indeed be owing to-the disappearance by natural causes of extended coatinents now broken into islands, as some have conjectured, which have retained only their more consolidated formations. But were this admitted, the supposition would militate, as is obvious, in another way against our author’s supposition. - In conclusion of this subject, we would at least confidently say, that Mr Lyell was bound to have entered more into the detail of facts upon which so important a principle as he has proposed could alone be established. It is by no means wanting in ingenuity and plausibility, but we think it must strike every one as being rather an induction from the hypothesis of “ ab« solute uniformity,” which it is calculated to support, than as flowing di- rectly from the facts which are intended to form its basis. - Chapter ninth contaius Mr Lyell’s views on the nature of the evidence afforded by fossil remains, considered as establishing a progressive deve- lopement of perfection in the organic structure of the objects of physiology, which have existed contemporaneously with a terrestrial surface immediately . below the strata in which they occur. Mr Lyell denies this opinion. His arguments are too briefly and inconclusively stated ; his love of magnifying exceptions rather than arguing from general laws is here again exemplified. Without hazarding an opinion on the very interesting question agitated, a question entirely of facts, we will only say that Mr Lyell’s view of it ap- pears incomplete and unsatisfactory; and that, at all events, it ought cer- tainly to have been postponed to another portion of the work. 174 Analysis of Scientific Books and Memoirs. Chapters tenth to seventeenth inclusive, contain an elaborate and inters , esting detail of the proofs of the great existing energy of water, as a mo- difying, disintegrating, and transporting agent. As our author has in ge- neral confined himself to modern and well authenticated events, the sub- ject becomes very interesting, and the details mark much care and industry _ in their collection. The transporting effects of running water, of springs, of the ocean, the formation of marine and lacustrine deltas and bars are successively considered. We shall make some extracts from this part of the work, and commence with a notice of the great flood at Tivoli in 1826, of which no account has appeared in this Journal. _ § Flood at Tivoli, 1826,—We shall conclude with one more example, de- rived from a land of classic recollections, the ancient Tibur, and which, like all the other inundations to which we have alluded, oceutred within the presetitt century.. The younger Pliny, it will be remembered, describes, a flood on the Anio, which destroyed woods, rocks, and houses, with the most sumptuous villas and works of art. For four or five centuries con~, secutively, this headlong stream, as Horace truly called’ if, has often: remained within its bounds, and then, after such long intervals of rest, at. different periods inundated its banks again, and widened its channel. The last of these catastrophes happened 15th Nov. 1826, after heavy rains, such as produced the fioods before alluded to in Scotland. The waters ap- pear also to have been impeded by an artificial dike, by which they were separated into two parts, a short distance above Tivoli, They broke through this dike, and, leaving the left trench dry, precipitated themselves with their whole weight, on the right side. Here they undermined, in the course of a few hours, a high cliff, and widened the river’s channel about fifteen paces. On this height steod the church of St. Lucia, and about thirty-six houses of the town of Tivoli, which were all carried away, pre- senting, as they sank into the roaring flood, a terrific. scene of destruction to the spectators on the opposite bank. As the foundations were gradu- ally removed, each building, some of them edifices of considerable height, was first traversed with numerous rents, which soon widened into large fissures, until at length the roofs fell in with a crash, and then the walls sank into the river, and were hurled down the cataract below. | _ © The destroying agency of the flood came within two hundred yards of the precipice on which the beautiful temple of Vesta stands ; but fortu- nately this precious relic of antiquity was spared, while the wreck of mo- dern structures was hurled down the abyss. Vesta, it will be remembered, in the heathen mythology, personified the stability of the earth ; and when the Samian astronomer, Aristarchus, first taught that the earth revolved on its axis, and round the sun, he was publicly accused of impiety, ‘ for moving the everlasting Vesta from her place.’ Playfair observed, that when Hutton ascribed instability to the earth’s surface, and represented - the continents which we inhabit as the theatre of incessant change and movement, his antagonists, who regarded them as unalterable, assailed him, in a similar manner, with accusations founded on religious preju- dices. We might appeal to the excavating power of tie Anio as corrobo- Mr Lyell’s Principles of Geoloxy: 175 rative of one of the most controverted parts of the Huttonian theory ; and if the days of omens had not gone by, the geologists who now worship Vesta might regard the late catastrophe as portentous. We may, at least, recommend the modern votaries of the goddess to lose no time in making a pilgrimage to her shrine, for the next flood may not respect the temple-” Pp. 196, 197. We have already remarked, that in the formation of deltas, Mr Lyelt sees the embryos of new continents, and considers the strata of calcareous and siliceous matter, deposited by the rivers which form them, as real tock formations similar to those we now find constituting the whole crust of the globe. Here, as usual, however, Mr Lyell quotes only the examples favourable to his hypothesis, overthrows the doctrine of univer- sal formations with a stroke of his pen, and puts in the back ground all the difficult rocks to which his theory could never apply. The indurated formations of the delta of the Rhone are an interesting illustration of his views. « That a great proportion, at least, of the new deposit in the delta of the Rhone consists of rock, and not of loose incoherent matter, is perfectly as- certained. In the museum at Montpellier is a cannon taken up from the sea near the mouth of the river, imbedded in a crystalline calcareous rock. Large masses, also, are continually taken up of an arenaceous rock, cement- ed by calcareous matter, including multitudes of broken shells of recent species. The observations recently made on this subject corroborate the former statement of Marsilli; that the earthy deposits of the coast of Latguedoc form a stony substance, for which reason he ascribed a certain bituminous, salitie, and glutinous nature, to the substances brought down with sand by the Rhone. If the number of mineral springs charged with carbonate of lime which fall into the Rhone and its feeders in different parts of France be considered, we shall feel no surprise at the lapidification of the newly-deposited sediment in this delta. It should be remembered, that the fresh-water introduced by rivers, being lighter than the water of the sea, floats over the litter, and remains upon thé Surface for a consider- able distance. Consequently, it is exposed to as much evaporation as the waters of a lake ; and the area over which the river-water is spread, at the junction of great rivers and the sea, may well be compared; in point of extent; to that of considerable lakes. Now, it is well known, that so great is the quantity of water carried off by evaporation in some lakes, that it is nearly equal to the water flowing in; and in some inland seas, as the Caspian, it is quite equal. We may, therefore, well suppose that, in cases where a strong current does not interfere, the greater portion not only of the matter held mechanically in suspension, but of that also which is in chemical solution, must be precipitated within the limits of the delta; When these finer ingredients are extremely small in quantity, they may only suffice to supply crustaceous animals, corals, and marine plants, with the earthy particles necessary for their secretions ; but whenever it is in excess (as gencrally happens if the basin of a river lie partly in a district 176 Analysis of Scientific Books and Memoirs. of active or extinct voleanos), then will solid: deposits be’ formed, and:the- shells will at'once be included ina rocky mass.” Pp. 234, 235. [*) He afterwards says,‘ that the matter carried by rivers into seas and lakes is not thrown in confused and promiscuous heaps, but is ‘spread out: far and wide along the bottom, is well ascertained ; and that it must for the most part be divided into distinct strata, may in part be inferred where it cannot be proved by observation. The horizontal arrangement of the - strata, when laid open to the depth of twenty or thirty feet in the delta of. the Ganges and in that of the Mississippi, is alluded to by many writers; and the same disposition is well known to obtain in-all modern deposits of lakes and estuaries. Natural divisions are often occasioned by the interval of time which separates annually the deposition of matter during the perio- - dical rains, or melting of the snow upon the mountains. The deposit of each year acquires some degree of consistency before that of the succeeding year is superimposed. A variety of circumstances also give rise annually to slight variations in colour, fineness of the particles, and other characters. Alternations of strata distinct in’ texture, mineral ingredients, or organic contents, are produced by numerous causes. Thus, for example, at one period of the year, drift wood may be carried down, and.at another mud, as was before stated to be the case in the delta of the Mississippi ; or at one time when the volume and velocity of the stream are greatest, pebbles and sand may be spread over a certain area, over which, when the waters are low, fine matter or chemical precipitates are formed. During inundations the eurrent of fresh-water often repels the sea for many miles; but when the river is low, salt-water again occupies the same space. “When two deltas are converging, the intermediate space is often, for reasons before explained, alternately the receptacle of different sediment derived from the converging streams. The one is, perhaps, charged with calcareous, the other with argillaceous matter ; or one may sweep down sand and pebbles, the other impalpable mud. These differences may be repeated with con- siderable regularity, until a thickness of hundreds of feet of chertnting beds is accumulated.” Pp. 253, 254. The details of the destroying agency of the ocean, particularly on the east coast of England, are very curious, and in chapter fifteenth, are some interesting particulars accompanied with several good wood cuts of rocks in Shetland, extracted from Dr Hibbert’s elaborate work. But we have not room for farther extracts from this part of the volume. Chapters eighteenth to twenty-second contain an-interesting and papilla account of the effects of modern voleanos, though we do not observe much of profound or original remark. The first of these chapters discusses the ge= neral distribution of volcanic vents, and points out their remarkable con- tinuity and connexion with the scenes of earthquakes. We have to: make'a a short extract on the distinction of ancient and modern eruptions. F ‘© We must also be careful to distinguish between lines of extinct and ac- tive volcanos, even where they appear to run in the same direction, for ancient and modern systems may cross and interfere with each other. Already, indeed, we have proof that this is the case; so that it is not by : Mr Lyell’s Principles of Geology, 177 geographical position, but by reference to the species of organic beings alone, whether aquatic or terrestrial, whose remains occur in beds inter- stratified with layas, that we ean clearly distinguish the relatiye age of — yoleanos.of which no eruptions are recorded. Had Southern Italy be been known to civilized nations for as short a period as America, we should have had no record of eruptions in Ischia ; yet we might have assured ourselyes that the lavas of that isle had flowed. singe the Mediterranean was inhabi- teil by the species of testacea now living in the Neapolitan seas. With this assurance it would not have been rash to include the numerous yents of that isle in the modern voleanic group of Campania, On similar grounds we may class, without much hesitation, the submarine lavas of the Val di Noto in Sicily, in the modern cirele of subterrancan commotion, of which Etna and Calabria form a part. But the lavas of the Euganean hills and the Vicentin, although not wholly beyond the range of earthquakes in Northern Italy, must not be confounded with any existing volcanic sys- ‘tem ; for when they flowed, the seas were inhabitated with animals entire- ly distinct from those now known to live, whether in the Mediterranean or other parts of the globe. But we cannot enter into a full development of our views on these subjects in the present volume, as they would carry us inte the consideration of changes on the earth’s surface far anterior to the times of history, to which our present examinatign is exclusively con- fined.” —P. 235. Chapters eighteenth and nineteenth contain an sataneatins synopsis of the volcanic phenomena of the bay of Naples; we shall not enter into these details, but, chiefly as a specimen of the author’s style, we shall giye. his concluding paragraphs on the Buried Cities, eloquently showing the errors into which future geologists might be led, similar to those which Mr Tyell considers to warp the views of many of the present day, ** Yet favoured as this region has been by Nature from time immemorial, the signs of the changes imprinted on it during the period that it has served as the habitation of man, may appear in after-ages to indicate a series of unparalleled disasters. Let us suppose that at some future time the Me- diterranean should form a gulph of the great ocean, and that the tidal cur, rent should encroach on the shores of Campania, as it now adyances upon the eastern coast of England: the geologist will then behold the towns al- ready buried, and many more which will inevitably be entombed hereaf- ter, laid open in the the steep cliffs, where he will discover streets super; imposed above each other, with thick intervening strata of tuff or laya— some unscathed by fire, like those of Herculaneum and Pompeii, others. half melted down like these of Torre del Greco, or shattered and thrown about in strange confusion like Tripergola. Among the ruins will ke seen skeletons of men, and impressions of the human form stamped in so- lid rocks of tuff. Nor will the signs of earthquakes be wanting. The pavement of part of the Domitian Way, and the Temple of Nymphs, sub- merged at high tide, will be uncovered at low water, the columns remains ing erect and uninjured ; while other temples which had once sunk down, like that of Serapis, will be found to have been upraised again by subse- NEW SERIES, VOL. IV. NO. I. JANUARY 18351 M 178 Analysis of Scientific Books and Memoirs. quent movements. If they who study these phenomena, and speculate on their causes, assume that there are periods when the laws of Nature differ- ed from those established in their own time, they will scarcely hesitate to refer the wonderful monuments in question to those primeval ages. When they consider the numerous proofs of reiterated catastrophes to which the region ‘was subject, they may perhaps commiserate the unhappy fate of be« ings condemned to inhabit a planet during its nascent and chaotic state, and feel grateful that their favoured race escaped such scenes of anarchy and misrule. “© Yet what was the real eisaibeaes of Campania during those years of dire convulsion? ‘ A climate where heaven’s breath smells sweet and wooingly—a vigorous and luxuriant nature unparalleled in its productions —a coast which was once the fairy land of poets, and the favourite retreat of great men. Even the tyrants of the creation loved this alluring region, spared it, adorned it, lived in it, died in it.’* The inhabitants, indeed, have enjoyed no immunity from the calamities which are the lot of man- kind ; but the principal evils which they have suffered must be attributed to moral, not to physical causes—to disastrous events over which man might have exercised a control, rather than to the inevitable catastrophes which result from subterranean agency. When Spartacus encamped his army of ten thousand gladiators in the old extinct crater of Vesuvius, the vol- cano was more justly a subject of terror to Campania, than it has ever been since the rekindling of its fires.” —Pp. 359, 360. From the succeeding chapter upon Etna, we cannot resist quoting the following singular details. «© A remarkable discovery has lately been made on Etna of a great mass of ice, preserved for many years, perhaps for centuries, from melting, by the singular event of a current of red hot lava having flowed over it. The following are the facts in attestation of a phenomenon which must at first sight appear of so paradoxical a character. The extraordinary heat experien- ced in the south of Europe during the summer and autumn of 1828, caus ed the supplies of snow and ice, which had been-preserved in the spring of that year for the use of Catania and the adjoining parts of Sicily and the island of Malta, to fail entirely. Considerable distress was felt for the want of a commodity regarded in these countries as one of the necessaries of life rather than an article of luxury, and on the abundance of which in some large cities the salubrity of the water and the general health of the community is said in some degree to depend. The magistrates of Catania applied to Signor M. Gemmellaro, in the hope that his local knowledge of Etna might enable him to point out some crevice or natural grotto on the mountain, where drift snow was still preserved. Nor were they disap- pointed ; for he had long suspected that a small mass of perennial ice at the foot of the highest cone was part of a large and continuous glacier covered by a lava current. Having procured a large body of workmen, he quarried into this ice, and proved the superposition of the lava for seve- ral hundred yards, so as completely to satisfy himself that nothing * Forsyth’s Italy, vol. ii. “Mr Lyell’s Principles of Geology. 179 “but the {subsequent flowing of the Java over the ice could account for the position of the glacier. Unfortunately for the geologist, the ice was: 80, extremely hard, and the excavation so expensive, that there is no | bility of the operations being renewed. On the Ist of De- cember 1828, I visited this spot, which is on the south-east cide of the cone, and not far above the Casa Inglese, but the fresh snow had already ; ‘diearly filled up the new opening, so that it had only the appearance of the mouth of a grotto. I do not, however, question the accuracy of the conclusion of Signior Gemmellaro, who being well acquainted with all the appearances of drift snow in the fissures and cavities of Etna, had recog- “nized, even before the late excavations, the peculiarity of the position of “the ice in this locality. We may suppose, that, at the commencement of the eruption, a deep mass of drift snow had been covered by volcanic sand “showered down upon it before the descent of the lava. A dense stratum of this fine dust mixed with scorie is well known to be an excellent non- ~ conductor of heat, and may thus have preserved the snow from complete fasion when the burning flood poured over it. The shepherds in the “higher regions of Etna are accustomed to provide an annual store of snow “to supply their flocks with water in the summer months, by simply strew- ing over the snow in the spring a layer of volcanic sand a few inches thick, which effectually prevents the sun from penetrating. When lava had once consolidated over a glacier at the height of ten thousand feet above the level of the sea, we may readily conceive that the ice would endure as long as the snows of Mont Blanc, unless melted by volcanic heat from below. When I visited the great crater in the beginning of winter, (De- cember 1, 1828,) I found the crevices in the interior encrusted with thick ice, and in some cases hot vapours were streaming out between masses of ice and the rugged and steep walls of the crater. After the discovery of Signior Gemmellaro, it would not be surprising to find, in the cones of the Icelandic volcanos, repeated alternations of lava streams and glaciers.” “Pp. 369-371. In chapter twenty-second Mr Lyell endeavours to confute the doctrine of craters of elevation, founded by Von Buch and supported by Humboldt. Without entering into the merits of the question, we would suggest that “Mr Lyell has perhaps hardly paid sufficient deference, not to the great names, but to great powers and vast experience of these two profound na- turalists. The four concluding chabeers of the volume are devoted to some very interesting details respecting earthquakes and their effects, which our author considers of high importance, and adequate to most of the ef- fects of sudden violence and gradual elevation manifested in the strata of ‘the globe. His arguments for the greater magnitude of past effects are founded upon reiterated action similar to that of aqueous agents. He can-~ not make a mountain 2000 feet high at once, but he does it by 200 shocks at ten feet each. Now this mode of reasoning is less tenable than in the slow and constant degradation by water, because earthquakes are not among the ordinary and calculable forces employed by nature, and to pro-~ ceed upon the assumption of earthquakes returning at the same spot, with the same species of action (elevating or depressing, ) for hundreds of times, seems allowing more to her past than‘could be said for her present unifor« ” 180 Analysis of Scientific Books and Memoirs. mity ; beside there are, we suspect, many phenomena of the stratawhi could only be accounted for by single exertions of nature greater far any now on record, In his twenty-fifth chapter Mr Lyell has given, in- connection with the theory ef the elevation and depression of land, an ac- gount of the remarkable changes of apparent level in the Bay of Baja, and the testimony of the Temple of Serapis. The facts which bear on this in- teresting subject are luminously brought together, and the theory deduced is quite identical with that given in a former number of this Journal, to which Mr Lyell has liberally’ referred. A contemporary review of Mr _ -Lyell’s work, considers that he has brought forward “ an overwhelming ‘mass of evidence in proof of the fact, that this part of the Campanian coast was lowered at least twenty feet some time between the third and the sixteenth century, and re-elevated about as much again at the epoch of the eruption which produced the Monte Nuovo. The circumstances which demonstrate this are so clearly legible, that it would never perhaps have been disputed, but for the natural repugnance to admit so remarkable a local coincidence,of elevation and depression to nearly the same extent, as -well as the strong prejudices existing in regard to the immobility of the land, by which we have probably been blinded to the force of many simi- lar facts.” In the conclusion of his volume, Mr Lyell discusses the relative amount of subsidence and elevation caused by earthquakes, and conceives, upon the grounds of his theory, that the former predominated ; since otherwise the accumulations which upon any hypothesis must have been immense from the productions of volcanos, and the transportation of materials to the sur- face of the globe by springs or other causes, must have sensibly increased the railius of the globe, and an equalizing effect must therefore be admitted by local subsidence, or (as we rather suspect) by some equiparate cause. Now, as we consider this assertion of Mr Lyell one of the best founded in the volume, we must take this oportuity of rescuing it from the very unce- remonious and unwarrantable condemnation which it has received in the review just quoted. “‘ This isa problem” it is there said, “ which we have no data for solving. Mr Lyell assumes without argument, that the dimensions of the globe are inyariable, and then concludes for an excess of subsidence over elevation, in order to compensate the continual produc- tion of fresh matter from the interior of the globe in shape of laya, and the deposits of mineralized springs. But as we consider the assumption un- warrantable, the inference is of course equally so.” Here there is an entire oversight of the remarkable fact demonstrated first, we believe, by La- place, that since the time of Hipparchus the duration of the solar day has not varied one hundredth part of a centesimal second,” a quantity which corresponds to an increase of the terrestrial radius almost infinitesimal, and which may be shown not to amount to many feet. This extraordi- nary deduction, demonstrable on the most undeniable principles, points to a wonderful compensation of opposite errors, We close Mr Lyell’s book, as we commenced it, with feelings of real gratification, with a high opinion of his industry and talents of combina- tion and classification, and with a conviction of his possessing original powers, which we would wish to see more drawn upon in the succeeding volume, or, as we hope and expeet, volumes of his work. * Laplace, Systeme du Monde, 5me, Kd. tome ii. p. 87. Scientific Intelligence. 181 wee ~~ Axr. XVII—SCIENTIFIC INTELLIGCE iii I. NATURAL PHILOSOPHY. , = METEOROLOGY: hs airedat of the Georgia Meteor and Afrolite—Having recently re- ceived from Dr Boykin, specimens of the meteoric stone which fell in For- syth, in Georgia, in May 1829, we are induced to republish an extract from an original remem of the facts, as it appeared in the newspapers at the time. “ Between three and four o'clock, on the’ Sth instant, on that day, a small black cloud appeared south from Forsyth, from which two distinct explosions were heard, following in immediate succession, succeeded by a tremendous rumbling or whizzing noise, passing through the air, which lasted from the best account, from two to four minutes. *€ This extraordinary noise was, on the same evening, accounted for by Mr Sparks and Captain Postian, who happened to be near some negroes working ina field, one mile south of this place, who discovered a large stone descending through the air, weighing, as was afterwards ascertained, thirty-six pounds. “ The stone was, in the course of the evening, or very early the next morning, recovered from the spot where it fell. It had. penetrated the earth two feet and a half. The outside wore the appearance as if it had been in a furnace: it was covered about the thickness of a common knife blade, with & black substance somewhat like lava that had been melted. On breaking the stone, it had a strong sulphureous smell, and exhibited a metallic substance resembling silver. ** The stone, however, when broken, had a white appearance on the in- side, with veins. By the application of steel, it would produce fire. _ © The facts as related, can be supported by many individuals who heard the explosion and rumbling noise, and saw the stone-—Eias Beatu.” The following notice, forwarded to the Editor by Dr Boykin, of Geor- gia, under date of June 2, 1830, corresponds substantially with the above. *€ No one can tell from what direction the meteor came.—The first thing noticed was the report, like that of a large piece of ordnance; some say the principal explosion was succeeded by a number of lesser ones in quick succession, similar to the explosions of a cracker ; one has told me the se- condary noise was only a reverberation. Very soon after the explosion, some black people heard a whizzing noise, and on looking saw a faint * smoke’ descend to the ground ; at which time they heard the noise pro- duced by the fall of a stone ; they ran to the spot, for they saw where it fell, and discovered the hole it had made in the ground, being more than two feet in a hard clay soil: the negroes and others who went early to the spot, say they perceived a sulphureous smell. The stone wee thirty- six pounds: it fell at a small angle with the horizon.” Having received the specimens, just as this number of the Journal js about being finished, I can only add the following notice: The colour 182 Scientific Intelligence. « of the interior of the stone is a light ash-gray, and very uniform, ex- cept that it is sprinkled throughout with thousands of brilliant points of metallic iron, having very near the colour and lustre of polished silver. The iron is rarely in points larger than a small pin’s head, but the points are so numerous that nearly the whole of the powder of the stone is taken up by the magnet, even when it is in fine dust, and by a magnifier the little points of iron can even then be seén standing out from oe magnet. It greatly resembles the Tennessee meteoric. ’ It has the usual black crust on certain parts, and this, though iui: a semi-fused substance, exhibits bright metallic points when a file is drawn across it. A similar black crust is seen pervading the stone in some pla= ces through its interior, and’ forming where it is seen a cross fracture, black lines, or veins. The stone is full of semi-fused black points and ridges similar to the crust, and its entire mass seems half vitrified in points, so as to resemble an imperfect glass. The specific gravity, as ascertained by Mr Shepard, is 3.37.—American Journal, No. 38, pp. 388, 389, _ 2. Notice of the’ circumstances attending the fall of the Tennessee Me= teorites, May 9, 1827.—On Wednesday the 9th inst. about 4 o'clock p.m. the day being as clear as usual, my son and servants were planting corn in the field, they heard a report similar to that of a cannon, which was continued in the air resembling the firing of cannon or muskets by pla- toons, and the beating of drums as in a battle. Some small clouds with a trail of black smoke, made a terrific appearance, and from ‘them, with-. out doubt, came a number of stones with a loud whizzing noise, which struck the earth with a sound like that of a ponderous body. One of these stones my son heard fall about fifty yards from where he was. In its de- scent to the ground it struck a paupau tree of the size of a small hand spike, and tore it to pieces as lightning would have done; guided by the tree, he immediately found the spot, and there he found the stone about eight or ten inches under the ground ; this stone weighed five pounds and a quarter. Mr James Dugge was also present. They stated that the stone was cold but had the scent of sulphur. On the same day, and about the same time, my son-in-law, Mr Peter Ketsing, was in a field with his Jabourers, about one mile distant, when a stone fell which weighed eleven pounds and a-half. This took place near him, his wife, and three other women. A number of respectable men were present when it was found and taken up ; it was twelve inches under ground. I have seen one that fell at Mr David Garret’s, and part of one that fell at Mr John Bones’, I have also heard of one more that has been found. These stones are perfectly similar, glazed with a thin black crust, and bear the marks of having been through a body of fire and black smoke. Many gentlemen who have been excited within a few days to come to my house to see them, say they never saw such before. The editor of the paper says the noise was heard ten or twelve miles or more. I have nothing to add, says Professor Silliman, to the descriptions of this stone already published, except that the innumerable metallic points which Chemistry. 183. are visible through the light gray (almost white) surface of the mass are nearly as brilliant as silver, although they have obviously been rounded by heat. They are attended by an immense number of brilliant black vitre- ous globules, which have every appearance of perfect fusion, and the en- tire mass has that harsh acrid feel which belongs to lavassand trachytic The black crust has evidently been in a state of at least pasty fusion ; its roughnesses are rounded, and on drawing a file over any of its prominent points, bright metallic iron is immediately uncovered. There is no account of a fire-ball attending these meteorites, but as it was full day light and probably sunshine, we cannot conclude that there was no fire-ball. It is most probable that there was one.—American Journal, No. 38, pp. 378, 379. . rm Il. CHEMISTRY. 3. Composition of Mellitic Acid.—Messrs Liebig and Wohler have ana- lyzed the mellate of silver, and found that when burned with peroxide of copper, it gives off a gas which is absorbed entirely by caustic potash. From their results they deduce the following composition : Theory. Experiment. - 4 atoms Carbon, 24 50 50.21 3 do. Oxygen, 24 50 49.79 Atom of mellitic acid, = 48 100 100 ‘The atomic weight ascertained by experiment is 49.5, which comes very near the composition above stated. 4. Succinic Acid.—The same chemists have made a new analysis of this acid also. The composition obtained, as above, for mellitic acid, is the same as that obtained by Berzelius for the composition of succinic acid, except that the latter contains also two atoms of hydrogen. By subliming the succinic acid in chlorine, and by passing a current of chlorine through a solution of the acid in water, Liebig and Wéhler attempted to abstract the hydrogen from the succinic, and to convert it into mellitic acid, but without success. The acid they obtained had 50 for its atomic weight, and consisted of 2 hyd..+ 3 ox. + 4 car., which indicate pure succinic acid, 4. Paratartaric Acid.-Berzelius has given this name to the tartaric acid of the Vosges, long ago observed by John and Gay-Lussae, to differ from common tartaric acid. By the analysis of Berzelius, it proves to have not only the same atomic weight, but also the same atomic constitution, and to contain the same per centage of the several constituents. He calls it therefore Para-tartaric, to denote its difference from, and yet its intimate connection with, the common tartaric acid. The crystallized Para-tartaric differs from the tartaric, in being ofa different form, in requiring five times its weight of water for solution, while tartaric acid dissolves in half its weight, and in containing two atoms of water, one of which is driven off 184 Scientific Intelligence. - by a gentle heat. The Bi-paratartrate of soda is more soluble than the: tartrate, but the same salts of potash are alike difficult of solution, and both form two double salts, with oxide of antimony. One of the double tartrates can be obtained only in the form of a gummy mass, The corres sponding paratartrate crystallizes in small needles, becoming opaque and milk-white in the air, from loss of water. But the salts of lime are the most interesting. Both contain four atoms of water, and therefore both have the same per centage of all the constituents. The paratartrate, however, is the less soluble, and from this property is derived the best mode of dis tinguishing or separating the two acids. If a portion of the tartrate and paratartrate of lime be dissolved, each in a separate vessel, (or in the same,) in miuriatic acid slightly diluted, and caustic ammonia added to saturation, the Paratartrate speedily falls as a semi-crystalline white opaque precipitate ; the ¢artrate, on the other hand, is not thrown down, till the liquid is much concentrated, when, after some time, crystals in square octahedrons begin to be deposited on the sides of the glass. 6. Salicine.—This new substance, obtained from the bark of the willow, occurs in prismatic crystals, and is very bitter. 100 parts of water, at the temperature of 19° 5 cent, dissolve 5.6 parts of salicine. Its solubility in- creases with the temperature, and boiling water will dissolve it in any pro- portion. It is soluble in alcohol, but ether and the essential oils do not dissolve any of it. Concentrated sulphuric acid poured upon the salicine gives it a fine red colour, like that of bichromate of potash. It melts four degrees above the heat of boiling water, an increase of heat gives it a fine citron yellow colour, and renders its fracture like that of a resin. It is composed, according to MM. Pelouze, Jules, and Gay-Lussac, of Carbon, 55.49 2 Proportions: Hydrogen, 8:18 “2 Oxygen, 36.33 1 100.00 Its composition may be represented by two volumes of olefiant gas, and one of oxygen.-Ann. de Chim. June 1830, p. 220. . 7. Carburet of Sulphur not decomposed by Electric forces.—In this Jour=’ nal, No. iii. New Series, p. 183, we have mentioned M. Becquerel’s re- markable experiment on the decomposition of carburet of sulphur by small electric forces. According to M. Wohler, the black deposition on the sides’ of the tube is nét carbon, but merely the sulphuret of copper produced from the sulphur in the sulphuret of carbon. —Poggendorf’s Annalen, tom: 18, p. 482, . III. GENERAL SCIENCE. ‘ 4 8. Mortality among Leeches during storms. (Fer. Bull.) —That atiio- spheric changes have a remarkable influence upon leeches, is a well esta- blished fact. In 1825, M. Derheims, of St Omer, ascribes the almost sud- den death of them, at the approach of, or during storms, to the coagulation List of Scottish Patenis. ¥ 185 of the blood of these creatures, caused by the impression of the atmospheric electricity. This opinion, which at that time was the result of theory, he _ confirmed in the month of March last, by direct experiment—Ann. des Sciences d Observation. 9. Prizess—At the Anniversary Meeting of the Royal Society of London on the 30th November, the President announced that the Council had adjudged the Royal Medal to Dr Brewster, for his recent communications on Light ; and the Copley Medal to M. Balard of Montpellier, for his _ discovery of Brome. Arr. XVIII.—LIST OF PATENTS GRANTED IN SCOTLAND . SINCE SEPTEMBER 16, 1830. 28. September 16. For an Independent Safety Boat of Novel Construc- tion. To Writ1am Dosreez, county of Middlesex., 29. September 16. For certain Improvements in Distillation and Eva- poration. To Wit1iam Suanp, county of Kincardige. 30. September 16. For certain Additions to the Engines commonly cal- led Locomotive Engines. To Cuartes Biacxer Vicnotes, London, ‘and Joun Ericsson, county of Middlesex. 31. September 16. For an Apparatus calculated to prevent or render less frequent the explosion of Boilers in generating Steam. To Joszeru Cocuaux, London. 32. September 17. For certain Improvements in Machines or Machine- ry for Cutting Timber into Veneers or other useful forms. To AtEx- anper Craic, Mid-Lothian. 33. September 17. For certain Improvements in the Process of Making and Purifying Sugars. To Marmapuxe Rostnson, Junior, West- minster. 34. September 22. For an Improved Fid. To Henry Grorce Pearce, Ricwarp Garpner, and JoserH Gaxrpner, Liverpool. 35. September 22. For certain Improvements in the construction of Wheels for Carriages to be used on Railways. To Wittiam Losn, county of Northumberland. 36. October 16. For an Improvement in the Manufacture of Painting- Brushes and other Brushes applicable to various purposes. To TimoTHy Mason, Middlesex. 37. October 16. For an _Improvement in the Preparing or Making of certain Sugars. To Wri11am Aucustus ArcuBoLp, Middlesex.’ 38. October 21. For certain Improvements in the Apparatus or Machine- ry used in the Processes of Brewing and Distilling, To 4ineas Correy, Dublin. 39. October 21, For an Improved method of Lighting Places with Gas. To Micuart Donovan, Dublin. 40, November 11. For an Economical Apparatus or Machine to be ap- plied in the process of Baking for the purpose of Saving Materials. To Rozsert Hicks, Middlesex. 186 Mr Marshall’s Meteorological Observations 41. November 23. For certain Machinery, and the Application” thereof ‘to Steam Engines for the purpose of Propelling and Drawing Carriages »-on Turnpike Roads and other Roads and Railways. To Joun Hearon, Wittiam Heaton, Geonce Heaton, and Revsew Heaton, county of Warwick. 42. November 23. For certain Improvements in Printing Machines. — To Aucustus ArrLecatu, county of Kent. 43. November 23. For certain Improvements in Making or Preparing Saddle Lining, Saddle Cloth, and Girths for keeping Saddles in their place on Horses or other Animals of burden. To Samuzt Crarke, county of Devon. 44. November 23. For Improvements in Evaporating Fluids pear to various purposes. To JoserH Gipss, county of Kent. ,- : 45. November 23. For certain Improvements in Machinery or Appara- tus for Printing Calicoes and other Fabrics. To Marnew Busu, Dum- _ barton. 46. November 23. For certain Improvements on Locomotive and other Carriages or Machines applicable to Rail and other Roads, which Improve- ments or part or parts thereof are also applicable to Moving Bodies on Water, and Working other Machinery. To Tuomas Bramtey, county of Surrey. . 47. November 30. For certain Improvements on Machines or Appara- tus for Measuring Land and other Purposes. To James CHESTERMAN, county of York. Art. XIX.—Summary of Meteorological Observations made at Kendal in September, October; and November1830. By Mr Samurt Mar- SHALL. Communicated by the Author. State of the Barometer, Thermometer, &c. in Kendal for September 1830. Barometer. Inches. Maximum on the Ist, - - - 30.07 Minimum on the 23d, - - - (28.98. . Mean height, - - - : 29.51 Thermometer. Maximum on the 4th, : - - 61° Minimum on the 30th, - - - 39° Mean height, - - - - 52.01° Quantity of rain, 8.027 inches. Number of rainy days, 22. Prevalent winds, south-west. In the summary of the weather for this month, the almost constant rain we have had must be noticed, as out of the 30 days there has been rain on 22 of them. About the time of the equinox, violent gales of wind prevail- ed for many days both before and after the 23d. The barometer has kept about a mean between 29 and 30 inches, during the greater part of the month. The mean temperature of the month has been very nearly equal made at Kendal in September, October, and Nov, 1830. 187 to that of June, and yet the weather generally has been considered cold and chilly. The aurora borealis has been seen during the month, and it has always been followed by rain in about twenty-four hours after its ap~ pearance. The wind has been in the west and south-west 21 days. October. Barometer. Inches. Maximum on the 10th, - a 30.38 Minimum on the 29th, os - : 29.32 Mean height, - - - “ 29.98 Thermometer. Maximum on the 8th, - Bt “ 60° Minimum on the 17th, ~ - 3 30.5° Mean height, . . a 48.37° Quantity of rain, 4.695 inches. Number of rainy days, 16. Prevalent wind, west. Since the 18th we have had almost continued rain ; before that time we had about a fortnight of dry weather. On the whole, the early part of the month was very fine, and the barometer during the whole of the month has been high. The thermometer has indicated frost only on four nights, and in the day time we have had none. No snow has yet been observed on the hills. On the evening of the 5th a luminous arch of light crossed the heavens, and lasted at least an hour, from 8 to 9 o'clock. No streamers were observed, probably on account of the moonlight. November. Barometer. Inches. Maximum on the 24th, - > - 30.24 Minimum on the 7th, - - : 28.74 Mean height, - - - : 29.55 Thermometer. Maximum on the 4th, - - . 55.5" Minimum on the 19th, 24th, and 25th, - - 31° Mean height, - - - - icine 43.10° Quantity of rain, 10.023 inches. Number of rainy days, 24. Prevalent wind, south-west. The barometer has been mostly low during this month, and as yet we have had very little frost ; indeed none except on the three nights above- mentioned. The aurora borealis was seen on the evening of the 3d. Un- til the 18th we had not one day on which rain did not fall, mostly in large quantities, and during the greater part of the day. From the 18th of last month to the 18th of this, there were but two days when rain was not measured, The difference in temperature between the days and nights has been very trifling, and generally but a few degrees. 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Arr. I.—Meeting of the Cultivators of Natural Science and Medicine at Hamburgh, in September 1830. By James F. W. Jounston, M. A. &c. &c. Communicated by the Author. Wahrend man in der altern zeit die naturforschung als eine angenehme aber nutzlose Beschiftigung und als ein harmloses Spielzeug miissiger Kopfe ansah, hat man sich in der neuesten zeit immer mehr von ihrem grossen Einfluss auf den Cultur- Zustand und das Wohl der Vélker iiber- zeugt ;—und so sehen wir die Lenker der Volker bemiiht grossartige An- stalten zu ihrer Beférderung und Erweiterung zu errichten. Whereas, in former times, men regarded the inquisition of nature as a pleasant but useless employment, and as a harmless pastime for idle heads, they have, of late years, become every day more and more convinced of its influence upon the civilization and welfare of nations, and the leaders of the people are everywhere bestirring themselves for the erection of esta- blishments to promote its advancement and extension. Tiedeman’s Address to the Meeting at Heidelberg in 1829. Mazy illustrations of the fact stated in this sentence of Ties deman’s oration are to be found in our own country, in which the change of public opinion in regard to scientific pursuits has been nearly as great as in any other ; ; but no single illus- tration of it to be met with in any country is more strikingly instructive, than what is contained in the history of the Society of German Scientific Men. Commencing at its outset with the trifling concourse of some twenty lovers of natural science, it has every year augmented and grown,—despite of the openly NEW SERIES, VOL. IV. NO. 11. APRIL 1831. N 190 Mr Johnston’s Account of the ~ avowed hostility of some governments, and the secret espionage of others,—till, in the short space of nine years, it has attained to the character of a great national congregation, of which the most distinguished naturalists of the age are proud to be mem- bers, and which kings vie with each other in honouring. At - first a few cities only were open to them, and the dread of political associations shut many gates against them ;—now their task is to choose among many rival claimants, each of which would gladly‘entertain them. They are borne along now by the tide of public opinion, directing at once and directed by it; and the honour formerly bestowed willingly on individuals, from a knowledge and appreciation, in some degree, of their labours, is now bestowed with equal cheerfulness, and with great increase, on the whole body of indefatigable men, of which individual philosophers are but members. The Society of German Naturalists owes its origin to Pro- fessor Oken of Munich. ‘This indefatigable and free-minded man was formerly Professor of Natural History in the Univer- sity of Jena in Weimar, to which chair he was appointed in 1807. He was already favourably known for five or six volumes in natural science, especially zoology ; and, amidst his profes- sional labours, he found leisure for adding every year one or two to their number, Among these was 4 System of Natural Science, A Treatise on Light and Heat, and A System of Na- tural History. In 1817 he commenced at Jena a monthly jour- nal of Literature and Science in a quarto form, of which he still continues to be the editor. But the times were critical, or men in power, at least, thought them so. The principles of the Holy Alliance demanded a strict surveillance of the periodical literature ; and it was dangerous for small states to give coun- tenance to liberal men, or to permit political treatises to be published in their dominions. Oken cared little for men in power. He acted independently, and admitted into his Jour- nal some articles of a political nature, which gave high offence. The consequence was the intimation, “ either you must dis- continue the Jsis, or give up your chair.”—“ I told them,” said Oken, * I cared ngidiiaie for their chair, and I would go on with the Zsis in spite of them.” Of course, he lost his chair ; and, though he was allowed to remain, the Jsis was forbidden Meeting of Naturalists at Hamburgh. 191 to be published in Weimar. The publication therefore was transferred to Leipzig, while Oken continued to reside at Jena. In 1827 he obtained a chair from the King of Bavaria in the university of Munich, where he is now professor of physiology. _ Oken is a little man, probably near fifty years of age, of dark, yet sanguine complexion, and features whose habitual, if not natural, expression, is severity and determination. His dark eye and compressed lips have a forbidding and distance- keeping expression, for one can read upon them our own na- tional motto, “* Nemo me impune lacessit.” I do not know how far his power of saying severe things corresponds with his apparent inclination; but, if the one equal in amount only half of the other, I should be very sorry indeed to come under his lash. In conversation Oken is nevertheless pleasant and commu- nicative ; and I shall not soon forget the buzz and general. sensation,—the turning of eyes, and moving of feet, im the rooms of the Apollo Saal, on the occasion of our first public soirée, when the words, “‘ Oken is come !” were passed along the assembly. His friends crowded first to greet him, after which foreigners and other strangers were severally introduced ; and one could easily forgive the slight air of patronage with which he, though the last comer, welcomed them to the meet- ing, when we considered how goodly an mens his efforts had brought together. It was in the Jsis, and while still at Jena, that Oken pro- posed the plan of a great yearly meeting of the cultivators of natural science and medicine, from all parts of the German Fatherland. It was a noble idea, and nobly has it at length been brought about. But in 1821 Oken was still a tainted man,—the remembrance of his political sins was still fresh,— and his proceedings were consequently regarded with suspicion. Societies of all sorts were dreaded by the German governments, and they feared some hidden and dangerous design under the guise of a concourse of philosophers. But open influence could not be exerted against that which as yet had no being ; and, in 1822, the first meeting took place at Leipzig, Dr Schwiigrichen, Professor of Botany, in the chair. But what a contrast did this first meeting present to those of the last three - 192 Mr Johnston's Account of the or four years. At Leipzig there were about twenty came toge-» ther from the city, and these were joined by about a dozen’ strangers. It was, however, a beginning. In 1823 they met. in Halle in greater force, the celebrated botanist. Sprengel: being president, and Schweigger, well known for his Journal, which he has edited so indefatigably for twenty years, being secretary. Wurtzburg, famed as a medical school, was the seat of the third assemblage, D’Outrepont and Schénlein, of the medical faculty of that University, holding office. They now began to muster strong, both in numbers and in talent ; and here the meeting first obtained a consistency and fixed establishment. Frankfort received them hospitably in 1825 ; and the scientific men, and the authorities of the city, united in showing attention to the strangers. This place had the honour of first adding public respect to the private entertain- ments got up by the inhabitants to gratify their visitors; and,: among these private entertainments, that of Banker Bathman. deserves especial commemoration. If not the first, it was the: greatest yet paid to the entire body since their assembling commenced. Thus Frankfort, though the seat of no univer- sity, has a claim to much merit as a patron of scientific men. At Dresden, in the following year, preparations were also made: for their reception ; and the learned men connected with that seat of the fine arts, exerted themselves to make their visit a pleasant one. Seiler, the Director of the Surgical Academy, was president, and Carus the Anatomist.was secretary. The sixth meeting in 1827 was held at Munich, the seat of a flourishing University, opened only the preceding year under the favouring auspices of Louis Maximilian of Bavaria. This city also deserves well of the Society, and the attentions of the King were such as it had not hitherto experienced. Besides general attention to the comfort and accommodation of the whole body, particular attentions were paid to the individual members; and each person, during the period of his stay, had an invitation to dine at least once in the palace... They, began now to reckon their number by hundreds; and the amount and variety of subjects brought forward at their public meet- ings having increased beyond expectation, it was found neces- gary to break themseélves ‘up into sections, of which the bota- , Meeting of Naturalists at Hambirgh. 193 nists, an amiable and enthusiastic race of men, first set the example. ‘Thus time was gained ; men of like tastes and pur- ‘suits brought more frequently and more closely together; and “every one spared the infliction of dissertations and discussions upon the thousand and one subjects in which he felt no earthly interest ; for, though all cultivators of natural science rejoice in the pilaiernett, and admire those who successfully culti- vate any one department, yet each one has his own favourite branch or branches, beyond which he has little anxiety to roam, and unconnected with which discussions, however learn- ed, are often only tiresome. It was a judicious plan, then, to make the separation into sections, and thus to permit the shell and fly men to discuss the mysteries of their several ologies, without scandalizing the more grave and weighty pursuits of medicine and oryctognosy. This practice, begun at Munich, assumed a more extended and definite form at Berlin, and was finally arranged and consolidated at Heidelberg. Berlin gave a powerful impulse to the rising distinction of the Deutscher Naturforscher Versammlung. Every thing was done by the Prussian government, and under the immediate superintendence of the distinguished president, Baron Hum- boldt, for the convenience and accommodation of the strangers ; and arrangements were there first entered into by which the comfort of those from a distance was materially increased. Purses, even, as well as persons were attended to; and as liv- ing in hotels was considered too expensive for many, who, nevertheless, in a strange place, would be unable to provide themselves with private lodgings, several hundreds of the lat- ter were secured, chiefly in situations which gave convenient access to the places of meeting; and thus, the most complete strangers found themselves at once economically and conveni- ently situated. Fetes and excursions also were got up, and concerts given, which the royal family, and even the king him- self, graced with his presence; while poetry and music lent their aid to welcome and eulogize the votaries of science. The celebrated Humboldt presided, and Lichtenstein, the well known zoologist and South African traveller, held the office of secretary. The number of strangers who came from various parts of Germany and the northern countries, was 269 and 194 Mr Johnston’s Account of the f the total amount of members enrolled was 464. In this nu- merous assemblage of learned men, England had but one re- presentative. Yet one man may be worth a host, and the science of England suffered no derogation in the person of “¢ Charles Babbage, London.” This meeting at Berlin was by far the most splendid that has yet taken place, not from the number of strangers who attended it, for in that respect it was nearly equalled by the late meeting at Hamburgh, but from the circumstance of its being held in the capital of a powerful kingdom, where the government had shown a disposition to honour, and pay attention to scientific men,—in Berlin, the seat of the first university in Germany, where the professors of every science are among the most eminent men, and the collections in every department of natural history of the most splendid description to be found in the whole empire. It re- mains to see what Vienna can do, in the ensuing September, to rival the more northern metropolis. The beautiful and romantic city of Heidelberg was the seat of the following anniversary: Tiedeman and Gmelin, whose names have so long illustrated the university of Heidelberg, and whose labours have so much increased and diffused the knowledge of the anatomical and chemical sciences, held on this occasion the two official situations. At this meeting the number of strangers: amounted only to 193, and the total amount of members to 273, but it proved, nevertheless, a very interesting and satisfactory assemblage. Besides the zeal for science, there are always many circumstances which will influ- ence the resort of naturalists to any one place of meeting. The most important of these are the distance and the facility of ac- eess. To obviate the former in some measure, and to bring the meeting occasionally, at least, near the homes of all, it has become the custom to select in alternate years a city in the north and south of Germany, as the place where the assembly shall be held. But while this regulation secures the attendance of the men of the south, for example, it excludes almost, ab ipsa re, all those of the north from any participation in the pro- ceedings. There are few who have leisure for extended jour- nies of this kind every year, and still fewer whom circumstances will permit to undertake them. It does not follow, therefore, Meeting of Naturalists at Hamburgh. 195 from a diminution of numbers at any one anniversary, that any diminution in the zeal of philosophic men, or of their es- timation of the benefits to be derived from frequent general intercourse, has taken place, but simply that the facilities of attaining these benefits has been less. All circumstances con- sidered, therefore, the meeting at Heidelberg, though less nu- merous, by far, than that of the Prussian capital, was at once creditable to Germany,—creditable to the men of science in which it abounds,—and highly creditable to the city in which it was held, Among the autographs appended to the account of this meeting, drawn up by Tiedeman and Gmelin, I find ‘‘ Robert Brown, botanist, London,”—a man of whom Agardh said to me, ‘* I believe him to be the greatest botanist of this or any other country ;” and “ Andrew Duncan, Materia Medica, Edinburgh,” for whom many earnest and kind inquiries were made of me at the subsequent meeting in Hamburgh. It bas become now a matter of debate among the cities of Germany, which shall have the honour of receiving the society at their anniversary. To have the smallest chance, the city desirous of the honour, must either be represented by a depu- tation of members attending the meeting, or must otherwise express to the society through its president,—its desires, its claims, and the efforts it will make for general accommodation. An application of this kind from Prof. Oersted in Copenhagen, gave rise to a discussion of considerable importance., The so- ciety is entitled a German society, and by the spirit of the sta- tutes, its meetings can be held only in the cities of Germany. It was, therefore, proposed by Dobereiner, of Jena, and Muncke, of Heidelberg, that the terms of the statutes should be altered, leaving to all future meetings the power of nominating cities beyond the boundaries of Germany, as places of assembly. This motion was opposed by Lichtenstein, who argued very judiciously that it would be time enough to make such an al- teration in the statutes when the greater part of the German cities had been visited, and they found themselves at a loss where to go. The laws, therefore, were allowed to remain unaltered, and after some rivalship between Hamburgh and Gotha, the former was fixed upon as the seat of the ninth an- 196 Mr Johnston’s Account of the . niversary. It seems indeed an unreasonable demand on the part of the Copenhagen men of science, and one which would — greatly enhance the evils arising from distance, and want of access above alluded to, to ask a transfer of the place of meet- ing from Germany to the Danish islands. It is the king of Denmark who is anxious for a visit of so many learned men, in the hope that it may give an impulse to the science and education of his own dominions, which he is sincerely desirous to foster and encourage by every means in his power. But could the Danes and Swedes forget their mutual hostility,— and what have science and scientific men to do with national animosity,—it were better to institute a “ Scandinavian So- ciety,” in imitation of the German, and such as we hope to see before long in the British islands. This society would embrace Sweden, Norway, Finland, Denmark proper,—and the Duchies might also be included ; and in this wide field, which has pro- duced so many of the greatest men in science, there are ample materials for the formation of a scientific anniversary of the most splendid description. Were Berzelius, Oersted, and Pfaff to unite their efforts, the matter would be accomplished at once. There are in each country able and promising men to second them, and the governments of Denmark and Sweden would not be slow in rendering them every necessary assistance. The meetings would not be so numerous as those in Germany now prove to be, but from that very circumstance they would derive an additional interest, and be doubly beneficial. I con- sider it one of the greatest objections to the German meetings, that they have now become so numerous as to defeat the great object for which they were instituted,—to enable men of science to cultivate an acquaintance with one another. It was only necessary, for example, to attend the late assembly at Ham- _ burgh, to see how impossible it was for such acquaintances to be formed to any extent. The pleasantest days I spent there were at the commencement, when I had leisure to learn to know well a few men. When the crowd came, every body accosted every body, and no particular person could be met with at any one time or place. You saw faces, and were in- troduced to people for whom you cared nothing, and when you had at last laid your hands upon a man whose conversation Meeting of Naturalists at Hamburgh. 197 ‘you could enjoy, straightway another person insinuated himself between you, or sat down beside you, or came up with some foreign subject 1 in his mouth,—and so farewell to your quiet in- structive téte-a-téte. Itisall very well for a day or two, to run from flower to flower in this way,—dropping here a little word, and there a little word, but it is extremely unsatisfactory in the end; and so one finds it when he sits down at night, or after the lapse of a week so spent, to sum up what he has learned,—wherein he has been improved, or with what he has been enlightened,—he discovers that he has only been amus- ing himself,—and that he would have shown equal wisdom had he saved himself the toil and trouble of his long journey, ‘and spent his evenings instead, in the theatre or the ball-room. A great deal might be done by maintaining better order, and by more judicious arrangements than were put in force at Hamburgh, but more or less of the evil I have adverted to will always attend meetings equally numerous. The reports of these meetings hitherto published by the official directors, by Humboldt and Lichtenstein of the meet- ing at Berlin, and by Tiedeman and Gmelin of that at Heidel- berg, are only meagre outlines of the proceedings. They give the president’s opening speech in full, or mention that such and such things were done on certain days, and record only the titles of the papers read on the different branches of ‘science. They are nothing but mere forniularies—useful indeed in show- ing how and in what order the affair was conducted, but al- most entirely uninteresting in a scientific point of view. The best accounts published, have been those of Oken in the Isis. These contain not only the order of the proceedings, but all the important papers read,—an outline of the subjects discus- sed, at least in some of the sections,—notices by the editor of the persons or things most worthy of remark in the place where the assembly had met; and critical remarks upon things said or done, or suggestions for saying or doing them better on future occasions. One objection, however, lies against all these reports and statements ; they are excessively slow in mak- ing their appearance ; so that, even in Germany, many months elapse before any thing better than flying or ephemeral re- ports of the proceedings reach those whom circumstances had 198 Mr Johnston’s Account of the prevented from assisting at them. It is not my intention te follow the example of Oken, unless it be in occasional strictures upon the proceedings. Few individuals can obtain materials for a complete report; but I shall group together such a num- ber of desultory remarks regarding the proceedings, the per- sons assembled, and the places they represented, as will, I hope, amuse and interest my readers, while they at the same time give a general idea of the way in which these meetings go off among our German neighbours. By ‘the regulations of. the Society, the first public meeting takes place on the 18th of September. Members generally arrive before that time, however, and private meetings, both individually and in parties, take place several days earlier. One person drops in after another so slowly and gradually, that if you are on the spot when they begin to assemble, you have the opportunity of renewing old or of making several new and interesting acquaintances. The points of a man’s character which are to attach him to us are not always discernible at a glance, and it requires time and opportunity for other men also in whose memory we should like to hold a place, to become sufficiently acquainted with us, and with our claims upon their regard. I do not consider it enough to have seen and conversed with a great man; I wish, if possible, also that he should re- member to have seen and spoken with me. The latter wish implies a little more vanity perhaps than the former, but both spring, I conceive, from principles equally. virtuous and equally laudable. The one implies an admiration of that virtue of whatever kind which has raised another to eminence, the other, the desire of displaying like virtue ourselves. These two de- sires do not co-exist, or do not co-exist with equal ardour in the breasts of all men; and, therefore, all will not feel with equal force the objection I have stated above, as occurring to me when wandering among four or five hundred individuals, from whom it was required to make a judicious selection, and to become acquainted with those you had selected, all in the space of six days. I reached Hamburgh, fortunately, in suf- ficient time to enable me to see many on their arrival, and to me those days were by far the pleasantest which 1 was enabled to spend with a few whose time was still at their own disposal. 3 Meeting of Naturalists at Hamburgh. 199 Among this few was the amiable Agardh, with whom an ac- quaintance — in Lund, was here strengthened and im- proved. In Hamburg, a city of merchants, among whom a rise or fall in the funds of which it is the mart, is of absorbing inte- rest; a luxurious people, of whom it may truly be said that *‘ their God is their belly,”—it was difficult—it was impos- sible to find a man who, on account of mere scientific distinc- tion, deserved to occupy the chair of president at:the meeting of the Naturforscher. But in the head burgomaster, Dr Bar- tels, they founda man who, having formerly, written a book of travels, might with propriety be chosen,—who, from his knowledge, was capable of appreciating the objects and value of these scientific meetings ;—from his forensic talents was ca- pable of conducting the proceedings with ease and dignity,— and who, from his influence as chief magistrate of the city, was most able to provide for their accommodation, and to secure them that attention from official men to which they were entitled, and to which they had been accustomed. The president, there- fore, was well and prudently chosen, and it is an act of justice to a very worthy, kind, and talented old man to say, that his general conduct in the chair, his attention to individuals, and the judicious arrangements made under his superintendence for the comfort and enjoyment of all, were such as to give ge- neral satisfaction. Where any thing was found fault with, or there appeared any thing deserving of criticism, the universal feeling was, that he at least was not to blame. But in the choice of a secretary they were not so happy; they made indeed a very unfortunate, and, as it proved, a very unsatisfactory choice. | It is not my intention to say any thing harsh of Dr Fricke, but certainly his temper, his manner to- wards the strangers, and his general conduct in the discharge of his office, showed him to be entirely unfitted for so distinguished and peculiar acharge. Fricke stands high in Hamburgh as a surgeon, and is esteemed a successful operator; but his fame chiefly rests on his practice in curing syphilis without the aid of mercury. This practice was the subject of considerable discussion in the medical section during some of their visits to the Krankenhaus, (Hospital) of which Fricke is surgeon, we 200 _. Mr Johnston’s Account of' the Its route in the north, for it has been a travelling practice, was from England to Copenhagen, some twenty years ago, thence to Stockholm, and after being rejected in both places, it has taken refuge in Hamburg with Dr Fricke. That he has employed it successfully there is no doubt, and so, in certain circumstances, may any practitioner; and the precautions taken in regard to this disease by the authorities, and the con- sequent general mildness of the cases, sufficiently account for the success with which it has been attended in this city. Of the professional men in Hamburg, Dr Lehmann of the Botanic Garden was the person best fitted, as well by his scien- tific reputation as by his amiable and gentlemanly manners, for, the office of secretary. But there are always minor and un- — avowed reasons for such appointments, even among men of science; and Dr Fricke having the honour of bearing to the meeting at Heidelberg the invitation of the Hamburg burgo- masters, was almost as a matter of course appointed secretary to the ensuing meeting. To assist the secretary, a committee of directors was also appointed, chiefly medical men residing in Hamburg, that the arrangements for the reception of so many strangers might be more easily and more fully completed. On reaching Hamburg, the first duty of the stranger was to repair to the Stadthaus, the seat of the police and other minor courts, where, after elbowing his way through a tribe of raga- muffin-looking officers and still more wretched culprits, he found his way to the main staircase; and, on announcing him- self as a naturforscher, he was shown up one or two flights of steps, and ushered intothe grand room of state, where the ban- ners of the Hamburgers wave from the walls, and a series of portraits commemorate at once the illustrious friends of the Hanse towns, and testify at the same time the gratitude of the sovereign senate of the Merchant Queen of Germany. It depended entirely upon the day of the month whether the scene which presented itself on entering this room were worthy of especial notice or the contrary.. If it were still only the 13th or 14th of the month, he would see perhaps a dozen or twenty people standing in groups of three or four in different parts of the room, and an occasional rare ejaculation would reach him as some communication of interest was made,—probably re, Meeting of Naturalists at Hamburgh. 201° garding what persons were on their way to the meeting. Such was the case when Agardh and I on the 12th entered the room. Toall we were immediately introduced by the directors—each found some pleasant person or persons to converse with; and in cultivating personal acquaintance with men whose names you had probably often heard of, an hour passed quickly away. There were as yet no other public meetings than these two morning hours from nine to eleven, and they were chiefly for the purposes of enrolment, and the delivery of their tickets: of admission to the strangers as they arrived. But every succeeding day the interest of these mornings in-. creased exceedingly, and I consider it a strong inducement to be early in repairing to the place of meeting, that the scenes which ensue on every fresh arrival may be seen and enjoyed. A man in his travelling-dress walks into the room, and goes straight up to a group on his left, where he recognizes a well known face. A scream of joyful recognition, and a host of loud: exclamations, and a mutual behugging and beslobbering with salutations, first on the one sideof the face and then on the other, with various shaking of hands and other such gestures attract the general attention ; and ‘ who is that >—who is that ?” goes from one to another ; and then there is a move of the men who know him, or who have heard of and wish to know him, and the rest are beginning to resume their conversation, when a second interruption arises from the entrance of a great man in another science, and another set of men is set on the gui vive, and thus perhaps an entire hour may be most delightfully spent in merely looking on, in studying the physiognomy, and in watching the phases of expression and deep interest that pass over the countenances of different individuals by the mere presence and contact of others, votaries of the same branch of study, whom they have hitherto known only by their labours, but whom, though unseen, they have deeply venerated. The varied forms of salutation too are an interesting fea- ture of such an assemblage, at least to us islanders. Saluting among the men is no where uncommon, I believe, from Torneo to the Straits of Gibraltar, but in some places it.is more gene- ral than in others; and among some of the northern, the 202 ' “Mr Johnston’s Account of the Scandinavian people especially, it is ridiculously frequent. Were it not that these people smoke perpetually, and_there- fore disregard the trifling affair of breath, I should think it must in many cases prove a very disgusting custom, at least I who am no smoker have found it so. One little Polish pro- fessor from Warsaw, with whom I got very intimate at Ham- burgh, used to inflict upon me a regular salute on both sides at every meeting and parting, and on bidding him farewell, and obtaining his blessing, I received a triple portion twice told ‘from the worthy kind-hearted man. Fortunately for me his breathings were of the less tainted character. Then, on presentation to a stranger, there is the bowing, and the bowing, and the bowing-interminable. First make your bow in front, then take a step to the left and make another, then two steps to the right and make a third, then one step to the left and make another bow in front. This is Scandinavian, and is the least you can do to a gentleman; where ladies are concerned, a Swede begins at the one end of a long room, and bows slowly all the way till he comes in front of the ladies seated at the other. Or in Germany, you see two real bow- ing men come close up in front of one another till their heads almost touch as they begin to bob, and bob, and bob again like so many Chinese Mandarines. An old man with a pow- dered head and only a few long teeth in front,—a little man with an interminable smile upon his phiz,—an apothecary from Brunswick—might set up, I think, as a model of this kind of bobbing, for he finished it off in the most characteristic style of any man I saw at the meeting. He is, however, a very worthy and kind-hearted man; and should any of my readers ever find themselves in the city of Brunswick, an hour devoted to visiting him.they will not think ill spent. » And of verbal salutations, it is curious to hear so many dif- ferent in the same apartment. ‘ Mycka Tjenare” says the Swede,—* Hvorledes befinner de Dem” adds the Dane,—** Gut Tag, Gut Tag, wie gehts, lieber,” says the German;—while the French “ Comment vous portez-vous,” serves as a general form of address among those who do not understand each others tongue. Then there is the mixing up and compound- ing of languages where so: many are spoken, and so few cait Meeting of Naturalists at Hamburgh. 203 speak themall. In walking about in the large saloon where several hundreds are met together, you meet first a Swede, per- haps, and as he prefers his own tongue where he has an oppor- tunity of using it, you do your best at a few sentences, mak- ing good use of the words you have still retained rusting upon your memory since you left the western shores of the Baltic. Then you encounter a German, and in two minutes you set him a laughing, and in two seconds more you join him your- self, when he tells you of a couple of Swedish and one Danish | word you have popped into the sentence. You commence again with a third tongue only to make similar blunders, of which you never steer entirely clear, until you meet some one who can understand your native language. Such blunders in such a place, are unavoidable, and you hear them made so often that they cease to afford the amusement at first derived _ from them. The arrivals were occasionally by single individuals from the smaller cities, sometimes by pairs; more generally a band of men from one university came together, headed by an acknowledged leader. In all cases, the great men formed the centres of little systems of other men, well content to play the second fiddle for the honour of going along with him. In _ other words, they came like little chieftains attended by their tails. ‘Thus Agardh had his little tail of two men, as many as the university of Lund could afford. Berzelius could mus- ter but one recruit at Stockholm, for the journey was expensive ; but at Berlin his body guard was increased to three, while Pfaff and Wiedeman brought with them almost all the scien- tific men in their university. Pfaff and Wiedeman are the ornament and pride of the University of Kiel. Pfaff is known for the depth and extent of his knowledge in natural science, and for his works on physi- ology, pharmacy, and chemistry. He is an extremely lively and pleasant person, and has sometimes, it is said, expressed his opinions of things more openly than was agreeable to certain governments, by which his character was neither so well known, nor his worth so well appreciated, as by his own paternal mo- narch. ‘Travelling in Prussia some few years ago, when se- 204 Mr Johnston’s Account of the cret societies were all the order of the day, and the German governments in great alarm, he talked as usual,—more freely acd boldly than'was encouraged in that country. The Prus- sian government was offended, and Pfaff having got safe home, the ambassador at Copenhagen was charged to make a re- monstrance on the subject; but the King paid no attention, and. his ministers, therefore, could give the ambassador no satisfaction. Determined on pushing the affair, the ambassador had an audience of the King, and signified that the Prussian government expected Pfaff should be punished. Oh,” said — the King, “‘ Pfaff.is my very good friend, he has only been 2 _ little déstrait ; he has fancied he was in his own country, where he might’ say anything :” a terrible satire, coming as it did from the most absolute monarch in Europe. Pfaff paid a visit to London in the summer of 1829, and on his way home again, Dr Bowring boasts of the honour of saving from a watery grave, one of the lights of Kiel and of. the first men of his country. Wiedeman, by some colle the Astley Cooper of Germany, is ~ the most celebrated’ accoucheur in Germany, and the only sur-' geon who has performed the Ceesarean operation twice with suc- cess, upon the same individual.* He was formerly attached to the medical school of Brunswick, and being employed profes- sionally by the late ducal family, had the honour of bringing into the world the now expelled Duke Charles. Unfortunately he has been long afflicted with bad health, which has impaired his activity and usefulness ; still his devotion to science remains, and his-enthusiasm as ardent as upwards of threescore winters will permit. It was an effort which brought him to the meeting, for he had been complaining much. ‘‘ Iam in bad health,” he wrote to a friend in Hamburgh, “ but I will come to the meet- ing, if it should be on men’sshoulders.” Besides his medical pursuits, Wiedeman is also a zealous and learned entomologist, and my judicious friend Dr ‘Traill of Liverpool, has remarked to me, as illustrating one of the grand points of distinction between medical men in this country and their brethren on the continent, that Professor Wiedeman, at the late meeting in * The patient, I believe, was a little deformed ricketty woman, well known in Hamburgh. Meeting of Naturalists at Hamburgh. 205 Hamburgh, besides exhibiting drawings of the species of the genus Mydas, distributed also copies of a memoir in which he deseribes several new species of insects, confirming the propriety of the genius Achias of Lamarck, which has hitherto rested on a single specimen, and that one imperfect.* There is ely an eminent medical man in Germany, who is not also distinguished for his researches in some branch of natural history, and ** what a contrast is this,” he adds, ‘ to our pro- fession at home.” Berlin sent about twenty members, among whom, however, were but few of her eminent men. In the list are the names of Lichtenstein, Encke, Chamisso, and Otto, of the Botanic Gar- den. From Copenhagen came Professors Oersted of physics, Zeise and Forchhammer, of chemistry, Horneman of botany, Rheinhardt of zoology, and Jacobsen of physiology and anato- my. Christiania was unrepresented, as was also Upsala—the an- cient seat of natural science, possessing now but the shadowof its former fame. Stockholm, besides its Berzelius, sent Professor Eckstrém the head of the surgical school, and Wickstrém, the botanist ; Helsingfors in Finland, to which city the university has been removed since the fatal fire at Abo in 1827, sent Bonsdorf its professor of chemistry ; Petersburg sent Fischer of the Botanic Garden; Moscow, Fischer the zoologist and President of the Academy of Sciences; not the vegetable but the animal Fischer, as he wittily observed to me when pre- sented to him; while Warsaw sent its Jarocki, Mill, and Schubert, professors of zoology, physiology, and_ botany. Even Cracow sent Estreicher, its professor of botany, and Dor- pat its Struve, well known to astronomers. Breslaw, so dis- tinguished of late years among German universities for its eminence in natural science, sent not many men; but Otto the celebrated anatomist was of the number, and few places there- fore were more worthily represented. The little university of Rostock, sent two of its professors, Dr Vogel of general medi- cine, a name honourable among German physicians, and Professor Siemsen of mineralogy. Griefswald sent one only of its thirty teachers, Hornschuch, professor of zoology. * Wiedeman is also the author of an excellent work on non-European insects. NEW SERIES, VOL: lV. No. 11. APRIL 1831. ry) 206 Mr Johnston’s Account of the From Giessen came Wilbrand, professor of botany and zoology, the propounder of a new theory of the tides, and Pro- fessor Liebeg, of chemistry, a young man whose name is al- ready familiar to chemists for several important researches and discoveries, of great devotion to his science, of great labour, and of greater promise. The university of Kénigsberg, the farthest north of the German seats of learning, but once raised to such eminence by the prelections of Emanuel Kant, kept entirely aloof from the Naturforscher, and the city itself was represented by a single medical man. Saxony was in a state of confusion, revolution was at work in Dresden and Leipzig, and there came few from the universities to the meeting at Hamburg. Jena sent but two members of its professional body; Leipzig, the same number with a few physicians ; Freyburg and Marburg sent each one professor; and from the great university of Gottingen, (die perle deutschen hoch- schulen,) so near the place of meeting, and so famed for science, came also but one—Professor Osiander! Munich likewise sent only one, but he was the father of the assembly —Oken. Halle, celebrated for natural science, where Schweig- ger teaches chemistry—Nitzsch, zoology—Curt Sprengel and Kaulfuss, botany,—which boasts of 65 professors, and 1300 students, sent only two of its learned men to the meet- - ing, Germar, professor of mineralogy, and the celebrated Kru- kenberg of clinical medicine. The city sent also my good friend Dr Meissner, editor of a pharmaceutical annual, From Vienna came one professor, Jacquin of botany and chemistry, whose father’s works are known and prized by botanists, and with him young Dr Vivenot, a general favourite. Prague, the mother of the German universities, the rival towards the end of the fourteenth century of the famed schools of Bologna and Paris, and the proud nurse of 20,000 alumni—Prague now ranking in the second class of the German schools, in re- gard to natural science perhaps even lower, but numbering still 1500 students, and 55 public teachers,—the university of Prague sent but ome man, Professor Presl, of botany and zoology. Shame on thee proud Prague, and shame on thee too haughty Géttingen, even Archangel shames you, for from the shores of the White Sea she too sent her one man; even Meeting of Naturalists at Hamburgh. 207 the city of Baltimore, beyond the far Atlantic, where the sun looks down upon a new world, the city of Baltimore shames you, for she too sent her one professor! The city of Prague was more worthily represented in Batka, its talented and well known pharmacologist, from whom chemists have till lately been accustomed to receive their supplies of Selenium in the form of small medallions of Berzelius, its discoverer. From Heidelberg came the celebrated Tiedeman, with Pro- fessors Muncke, of physics ; Leuckart, of zoology; and Geiger, of pharmacy and pharmaceutical chemistry,—a man in high and deserved repute among his countrymen. Bonn sent three members of its professional body, among whom was Harless, known for his many works on practical medicine. The uni- versities of Tubingen, Wurtzburg, Erlangen, and Basel, were wholly unrepresented, while Erfurt, which preserves still a trace of the university it once boasted, sent forth the venerable Trommsdorf to preside over the section of pharmacy; and the commercial town of Bremen its Miiller, professor of phy- sics, and its distinguished botanist, Mertens, who was called to the chair of the botanical section. The academy of Soroe in Zealand, deputed its professor of zoology, Hauch; while the school of medicine in Brunswick sent Sillem, its professor of mineralogy, and Marx, of chemistry and physics. Marx is zealously devoted to optics, and to the examination of the optical characters of minerals. ‘ You know Dr Brewster,” he said tome; ‘* I esteem him more than all other scientific men. Does he come here ?—I should like much to see him.—Is he professor in Edinburgh ?”—* No, he has no public function.” “ But he will teach people when they come to him.”—* Oh, but he lives in the country, far out of the way, many miles from Edinburgh.”——“* Then he gives no lessons, but he should give lessons to spread the knowledge which nobody else can give. There is only Herschel and he in your country who have oc- cupied themselves with these subjects."—‘* But suppose he were in Edinburgh, and were to announce lectures, he would not obtain perhaps above two or three pupils on subjects ge- nerally supposed, so abtruse.”—* Ah, is it so; still he eee try to spread his knowledge.” What Marx says is indeed true: as things now stand much 208 Mr Johnston’s Account of the valuable knowledge must die with Dr Brewster. There are many things in practical science which books can never make known at all, and still more which they can neither make known so soon nor so well as a few short living sentences with refe- rences to instruments and experimental illustration. It were a desirable thing, therefore, if, in connection with our seats of learning, there existed certain overlying and available funds by which the services of eminent men might be occasionally se- _ cured, even in departments the most recondite and abstruse, so that they might have an inducement to dedicate a portion of their time to the instruction even of a very few. On the continent this is easily effected. Itis represented to the govern- ment, the King perhaps, that such a person is eminent in science, and he is without hesitation honoured with the title of Professor, and a certain salary, with power to lecture im a par- ticular faculty, that of philosophy for instance, which includes all natural science, except the strictly medical departments. If his manner or his subject be unpopular, or if from any other cause none take his tickets, he is at liberty to pursue undis- turbed his own investigations, while the title conferred on him is a just tribute of respect to his scientific reputation. In either case the state suffers little—his salary dies with him—science is advanced and benefited—the country is honoured as the means of that advancement—while it is provided also with a talented teacher, likely to keep the true scientific spirit alive in the land—and bound to instruct in the mysteries of his pecu- liar department any one who may feel himself drawn by con- geniality of disposition to similarity of pursuit. The worthy community of Hamburgh could not well un- derstand the meaning of all this gathering together from the four corners of the land; from either shore of the Baltic, and from where, with its broad belts, it girds and embraces the isles of Denmark.* The notes of preparation had been sound- ed for months before, and occasional notices in the Journals of the day, when business gave them leisure to catch a glance at them, told of a coming of medical men and Naturforscher, but, as it did not relate to corn, sugar, or currency, they turned to something else and thought no more about it... But when the 3° Meeting of Naturalists at Hamburgh. 209 time arrived, and there was a talk of public attention» to be paid to these strangers ; of the Stadthaus, being set apart for the place of enrolment and rencontré ; of the Boursen Halle, for the great mid-day assemblies ; of the Apollo Saal, for the mittags essen and the Soirées, and various other apartments, public and private, for certain minor sectional meetings as they were called; above all, when it was whispered abroad that there was likely to be some good eating and drinking, some dancing too and music, and a chance that the citizens of Ham- burgh might be called upon to pay for all this,—then—then to be sure, it became a matter of every day business with them, the stomach and the purse were equally concerned, and inquiries were neither few nor far between about the objects and intentions of all these strangers, and the probable expence they might cost them. You might hear the matter discussed over a shipping-list, or a newspaper, in the Boursen Halle; over a sample of coffee, probably on the Exchange, or a beef steak in a restauration. ‘‘ So many men come together to see one another, come so far merely to look at one another— nonsense!” And then said another, as he took up the thread of the affair, *‘ They say we are to feed them, but if the se- nate spend our money in that way, the town will be about their ears; the people will not stand it in these revolutionary times. When you or I go a travelling on our affairs toa strange place, nobody will think of treating us, and why should we treat these Naturforscher as they call themselves.” ** And I see,” said a third, ‘‘ why they elected old Bartels to be their president; they thought he could manage best. to squeeze a lot of good dinners out of us.” Thus the wise ones talked, pushing their hands into their pockets every now and then to see if their purses were safe. But the judicious and thinking men, though they did not pretend to understand all the objects of the meeting; though many of them were not qualified to appreciate them; and though many could not re- gard with an auspicious eye this taking by storm as it were, and forcing light, and learning, and liberality, into the very sanctuary of Momus; yet they thought, generally, that these strangers, being once within the walls, it. would be for their own credit to use them well for a few days, when they would soon be off again. 210 Mr Johnston’s Account of the The young men at the desk and the counter, as little in- structed at least as their masters, caught another species of in- fection, and ‘* what is a Naturforscher ?” became the common question among them. And when, in the mornings, they re- paired to the pavilions on the Alster, for their matitudinal cup of coffee, or in the evenings, when the letters were written, to sip their vespertinal glass of punch or sugar water, still the question was, “ have you heard any thing about these Natur- forscher, or what kind of fellows they are?” and then at the cry “da geht ein Naturforscher—there goes a Naturforscher,” there was a hustling and a justling, a knocking over of chairs and tables, and a scrambling for hats, as every one hurried to the door to see what the animal was like, and if it! walked on two legs or four on its way up the Jungfernstieg. These, and similar: traits of naiveté, as they occasionally reached our ears, were a source of infinite amusement. As it was impossible for one individual to attend more than two or three sectional departments, so it is impossible for one person, who has not more ample means of information than a stranger can be supposed to possess, to give an account of much more than what passed under his own immediate obser- vation. In continuing my remarks, therefore, I shall throw what I have to offer in regard to the proceedings of the as- sembly into the form of a journal, which will enable me to give more easily, and with more appearance of method, several little notices which could not without confusion be introduced in any other way. 18th, 14th, and 15th—days of preparation and peaiaiiier Every thing worth seeing in Hamburgh is. thrown open to the Naturforscher during the ensuing ten days, and the strangers, formed into little parties, spend their time in visiting such col- lections and sights as best suit their dispositions and pursuits. In Hamburgh these collections, of a public kind at least, are neither numerous nor remarkable. ‘That such should be the case was to be expected in a city wholly ‘swallowed up in the pursuit of gain. And yet there are some private collections which would do honour to any town, and which do double Meeting of Naturalists at Hamburgh. - 211 honour to ‘the individuals who have formed them. Of this kind is the well known and splendid mineral collection of Von Struve, the Russian minister, a collection which is now un- derstood to be sold to the Russian government. This: cabi- net has cost Von Struve twenty-five years diligent collection, is especially rich in Norwegian and Siberian minerals, and con- tains 7000 or 8000 specimens, many of them finely crystallized, of great value and beauty. The pleasure I had derived from examining this collection during a former visit to. Hamburgh was shared’ on my second visit in common with all the strangers who felt an interest in mineralogical sciénce—the minister hay- ing kindly consented that the section of mineralogy should meet in his house. Inferior to that of Struve, yet deserving of “mention as collected with zeal and in less favourable circum- stances, is that of Pastor Muller, containing 2500 specimens. This collection I had not the pleasure of seeing. Among eminent collections also must be particularly no- ticed the rich and extensive entomological cabinet of Mr Wilhelm von Wintem. This collection embraces the entire range of entomology, and possesses a degree of completeness in all its branches which is rarely to be met with. ‘ Von Wintem is an exceedingly young man, and a merchant,” said a young Swede to me, a zealous entomologist, * I cannot un- derstand how he has been able to amass'so splendid a collec- tion.” It would be the work of'a lifetime at least in most countries and to most persons, but Hamburgh has communi- cation with all the world, and the zeal of Von Wintem has known how to improve the advantages of his situation. No entomologist will visit. Hamburgh without thinking’ of Von Wintem’s collection, and they will find its possessor equally courteous in his. attention and willing to contribute to their gratification. Professor Lehmann has also a general collection of insects, but it is less worthy of mention than the rich pri- vate collection of the Messrs Sommer in Altona, which, being almost within gun-shot, may be spoken of in the same para- graph with the collections in Hamburgh. ‘This collection comprises only the Lepidoptera and the Coleoptera, but it is nevertheless reckoned one of the richest private collections in Germany. The best collection of birds is that of Mr Amsink, 212 ' Mr Johnston's Account of the which is certainly splendid for a private gentleman and ‘a mer- chant. It contains many fine birds in fine order, but its, riches consist chiefly of European species. + PUREE The only other collection worthy of particular notice is thé, museum of Mr Réding. This museum consists of two sub- divisions, containing natural productions and works of art, and’ is certainly a wonderful result of the patient and persevering industry of one private man, and he by no means rich. Réding, however, is rather a collector of curiosities than a scientific naturalist. ‘There are indeed many birds—many fishes—still more shells—some quadrupeds—a few minerals— with anatomical preparations and various other things crowded in the natural history apartment, and all these are named and classified after some author, but no one department approach- es completion. None of the different collections, except per- haps the shells, can even set up a claim to represent a depart- ment. Most of the specimens susceptible of the attacks of age, are also showing symptoms of decay, for while Réding has been advancing in years, his favourite collections have been growing old also, and unless some helping hand step in to his aid, the work of his whole life will not long survive himself. It would take a large sum to keep even this collec- tion in good condition, and it would only show a proper and becoming liberality in the city of Hamburgh to purchase it from its highly meritorious and industrious collector, and by spending a little money in repairing, save from destruction so interesting a memorial of one of its worthiest citizens. Réding’s desire for rarities is still unsatisfied, and the money he has to spare he expends rather in the purchase of new curiosities than in the reparation of the many he already pos- sesses. The part which composes the works of art is more perfect, because less susceptible of decay, and is far more sur- prising as the work of a private individual than the natural history portion. His works in amber, ivory, silver, and wood, are both very rich and very worthy of being visited. The whole forms a kind of Omnigatherum, in which every one will find something to interest him, and with this view it is thrown pen to the public once or twice a week at a trifling expence. On one of these days T visited Dr Schmeisser, who gives Meeting of Naturalists at Hamburgh. 213 lectures on chemistry in Hamburgh, and in whose auditorium the chemico-physical and pharmaceutical sections held its sittings. Dr Schmeisser is an old pupil and friend of the ve- nerated Dr Black, and has many pleasing recollections of Edinburgh. It is exceedingly interesting to hear old men talk of the chemistry of their youth, and of the wonder with which every new discovery was regarded. ‘ Soon after the discovery of the phosphuret of lime,” said Schmeisser, “ T was exhibiting its decomposition by immersion in water, and the spontaneous combustion of the phosphuretted-hydrogen formed—‘“ We must have you German fellows sent out of the country,” said a witty person to me, ‘‘ or you will be setting the Thames on fire.” And he told, with much glee, how, when - the method had become newly known, he formed a quantity of artificial spermaceti from some half-decayed muscles by means of nitric acid, and making it into candles, sent some of them to Blumenbach, with a notice that they were prepared from the legs of a man who in his life time had done no good, and how Blumenbach punningly replied to him, ‘ Mortui lucent qui in vita obscuri fuerunt.” Poor Schmeisser, he has not been too fortunate in the world, and bad health confining him to his room, prevented his taking any share in the pro- ceedings of the Naturforscher. On the evenings of these three days there were reunions in the Hotel de Russie, where a large room had been secured for the purpose. During this time our numbers were but few; there was more quiet conversation, therefore, and less bustle and looking about for friends than when the numbers had be- come much greater. ‘The only regret was, that one did not see among those assembled the persons he most anxiously looked for ;—there were many eminent men—but chemists did not desire chiefly to see eminent botanists—nor did the pure zoologist care much for the rience of the mere practical sur- geon or physician. 16th.—Dr Traill of Liverpool is the only Englishman yet arrived, and great disappointment is expressed that Edinburgh has sent forth so few. Dr Duncan has evidently been expect- ed, and many inquiries have been made concerning him, Among the surgeons, there is a considerable desire to see 214 Mr Johnston’s Account of the some of our Edinburgh men of the knife and lancet. * Your surgeons in Edinburgh are very bold,” said an eminent pro- fessor to me, the head of the Swedish school of surgery, “bolder than we want here on the continent. Your Lizars cares nothing for common operations ; ; he likes only the most hazardous. He performs an operation very daringly and very cleverly—goes home at night—writes it out for the Edin- burgh Medical Journal, and all is going on very well ;—but the next number comes—and the patient—is dead The strangers having now collected in considerable force, arrangements had been made for commencing the public din-- ners on this day. The directors had superintended the pre- - paration of the Apollo Saal, and a suite of rooms connected with it for this purpose. Dinners, wines, and refreshments: for the soirées, held from this time in the same place, were provided by the landlord of the Hotel de Russie, and the treasury of Hamburgh, notwithstanding the alleged complaints of a few individuals, had come liberally forward to defray cer- tain expences unavoidable in fitting up such a place for such an occasion. ‘The charge for dinner was fixed at two merks, about half a crown, for each person, exclusive of wine, and it was said that, to secure good dinners, the city gave something more. Had the rate been higher, the object in view, that of bringing the strangers as much together as possible, would have been. defeated, as many would have preferred dining more quietly and more comfortably at a restauration, which they could have done for a good deal less. At four o'clock, we began to take places at the different tables, of which about eighteen were ranged up the middle and along the sides of the room, but so bad was the attendance, that »before every one was served with wine and could boast of .a’ plate of ' soup, at least a full hour had elapsed. I expected: that we would have more regularity on the ensuing days, but’ on each. sue- ceeding one, as the numbers augmented, the noise and confu- sion, the running about, and the scrambling for places, in- creased to such a degree, that, when 500 or 600 assembled to dinner, it became perfectly intolerable. ‘None were admitted but those who were members, and no ladies but such as were wives or sisters of members. Burgomaster Bartels présided 4 Meeting of Naturalists at Hamburgh. 215 ‘at the principal table, and each of the directors had his place assigned him at one of the others. At the conclusion of din- ner, it was announced by Dr Fricke, that such gentlemen as chose to spend the evening at the theatre, would receive tickets from the directors at a reduced price. Of this offer many availed themselves, the consequence of which was, that the soirée, by far the most pleasant of all our reunions, was, on this evening, unusually dull and insipid. 17th.—Among the arrivals this morning at the Stadthaus, were Berzelius, Oersted, Pfaff, Wiedeman, and many other eminent men whom all were glad to see, and old friends parti- cularly, to meet again with kind greetings. An attempt was made during dinner to-day to drown the noise by the intro- duction of an excellent band of music, vocal and instrumental, which in some degree succeeded. But even this subjected us to another petty annoyance. During the interludes, parties of the performers went round the room with plates soliciting con- tributions, as any street-fiddler or ballad-singer might do. Such is indeed the custom in the caffés in Germany where music is found; the performers take their chance; but it ought to have been avoided on so particular and public an occasion as this; and whoever caused the music to be introduced, should also have caused it to be paid for. The evening rewnion passed off very pleasantly. There was a large assemblage—every one in a humour to please and to be pleased. A considerable sensation was created by the entrance and presentation of Oken, the founder of the society. It is very interesting to stand by and witness the various de- grees of familiarity and pleasure with which, where so many meet, different persons recognize the same individual. Some at once shaking hands—others saluting—others waiting till,they have made out the name of a man they have never before seen, and then bursting out into an exclamation of delight to be heard at the other end of the room. Legh 18th.—This morning’s was the last of our meetings at the - Stadthaus, the regular session of the assembly commencing on the 18th, and the entire mornings during the session of eight days being taken up with the business of the various sections. In the morning, Dr Traill and 1, with our countryman, Mr 216 Mr Johnston’s Account of the Palk, drove out to the suburb St George, to pay a visit to the hospital or Krankenhaus. Large and richly endowed institutions are not to be Ioaked for in a free town whose territories include but a few miles of ground without the walls, and the greater part of whose re- venue must necessarily be expended in keeping up a shadow of sovereignty and independent power; yet the hospital of Hamburgh, both for its magnificence and its general economy, would do honour to any city. The old hospital, or pest-house as it was called, having been burnt by the French in 1814, the present spacious building has been erected to supply its place. It was completed in 1823, at an expence of L.'75,000, and is intended to receive 1000, though it often contains 1200or 1400 patients. It is situated ina fine airy and dry situation on the suburb of St George, and on the shore of the Lake Alster, from which it is supplied with water. The internal arrange- ments correspond with the outward appearance. ‘The com- mon wards are 40} feet by 24, with a height of 13 feet, and contain 13 beds, being at the rate of 972 cubic feet for each bed ; the largest wards are 47 feet by 49, and contain $2 beds; and the entire number of rooms, with from 1 bed to 30, is about 200. Of these beds, 500 are set apart for medical, and 200 for surgical cases. The air is kept pure by common ven- tilators in the windows and in the floors of the upper story ; and the possibility of stagnation is prevented by a spacious corridor of 10 feet in width, which runs lengthwise through the middle of the one floor and along each side of the other, into which the doors of the chambers open, and to which the air has at all times free access. ‘There seemed much regularity in all parts of the house, and much subdivision of labour. One room, for example, was fitted up solely for the making of poul- tices, in which it was the business of one man to have them hot and ready at all hours. Another was set apart for the bandages, under chargeof a person who was answerable for all it contained, and who kept a regular account of all his transactions with the different wards. The bandages of linen, flannel, &c. were all numbered and kept in separate dove-cots, ready of every length and breadth, at a moment’s notice. ‘he number of male and female nurses is from 8V to 90, and there are at least 50 other ‘ Meeting of Naturalists at Hamburgh. 217 people constantly employed in various occupations connected with the establishment. The vast number of patients is accounted for by a portion of each wing being set apart on the one side for male and on the other for female lunatics, who amount in all to about 300; and by the circumstance of its being an hospital for the sup- port of incurable, as well as for che treatment of hopeful, cases. Patients of the former class, if allowed to accumulate, would very soon either destroy the efficiency of our hospitals, or swell them to a magnitude even greater than that of Hamburgh. The chapel for divine worship struck me as an exceedingly commendable part of the institution. It is a large handsome room of 55 feet by 34, is 30 feet high, and has inclosed gal- leries. Divine service is regularly performed in this chapel on Sundays and holidays; and the sick are at other times attend- ed to by the pastor of the hospital,. who has a very respectable salary of 4500 merks, or L. 260 a year. The salaries of the medical men differ in amount. The chief physician is allowed L. 380 a year, but he must live near the hospital, and is forbidden to practice. Three other physi- cians, for a daily visit of one or two hours, are allowed about L.30a year. The principal surgeon receives L. 120, and has his practice. ‘Three surgeons also live in the house, one of whom must always be at hand. They are allowed about L. 30 a year and their board. Crossing the Alster in a boat, we returned to the city by the Damm Thor, and reached the Boursen Halle soon after two o’clock, where we found the President Bartels delivering the inaugural discourse. It was short, friendly, unambitious, and without pretence,—a striking contrast to the splendid and elaborate oration of Tiedeman the preceding year at Heidelberg: * We have here in Hamburgh,” said the worthy old man, ** no rich museums and collections to boast of, such as you have met with in the metropolitan cities, and the seats of universities, where your former anniversaries were held; nor am [ at all fitted for filling this chair after the many eminent scientific men by whom it has previously been occupied ; but we shall only esteem you the more, and show you the greater kindness, that you have thus so honoured both the city and myself by your 218 Mr Johnston’s Account of the choice; and shall endeavour, by a reception worthy both of ourselves and you, to testify our sense of the important prac- tical advantages to be derived from the prosecution and ad- vancement of science.” Dr Fricke, as secretary, then read the laws of the society, which, as they may interest many of my readers who have never met with them in an English dress, I shall here tran- scribe. 1. At a meeting of German naturalists * and physicians held at Leipzig on the 18th of September 1822, it was resolved, that a society be formed, to be named the Society of German Naturalists and Physicians. 2. The chief object of this society is to afford an opportu- nity to the cultivators of natural science and medicine in Ger- many to become personally acquainted with each other. 3. Every person who has written upon natural ‘science or medicine is admissible as a member. 4. The composition of a mere inaugural dissertation does not entitle any person to be considered as a writer. 5. A particular election is not necessary, and no diplomas will be given. 6. All persons are admissible to the meetings who employ themselves with natural science or medicine. 7. Only members have the right of voting at the meetings. 8. Every thing shall be decided by the majority of voices. 9. The society shall meet every year, and deliberate with open doors; to commence on the 18th September, and con- tinue for several days. 10. The place of meeting shall be variable. At each an- niversary the place of meeting for the ensuing year shall be determined. 11. A president and a secretary, resident in the placd of meeting for the time being, shall conduct the affairs of the so- ciety till the ensuing anniversary. * Deutscher Naturforscher und Aertze. We have no words in our lan- guage corresponding to these two. The former means a cultivator of natural science in any of its branches, being much more comprehensive than our word Naturalist, as generally understood; while the latter in- eludes all cultivators of the healing art,—surgeons as well as physicians. Meeting of Naturalists at Hamburgh. 219 12. The president shall appoint the hours and place of meeting, and arrange the business, and every one who has any thing to bring forward must notify the same to him. 18. The secretary shall have charge of the minutes, the ac- counts, and the correspondence. 14. Both office-bearers shall subscribe only in the name of the society. 15. They shall make known as early as possible the autho- rity conferred upon them by the immediately preceding as- sembly, and at the same time take measures for making the ensuing place of meeting as generally known as possible. 16. At each anniversary the office-bearers for the ensuing year shall be appointed. Should the appointment not be ac- cepted, the office-bearers shall select another individual, and must at the same time appoint a new place of meeting. 17. Should the society lose one of its office-bearers, the sur- vivor shall nominate another. Should it lose both, those of the preceding year shall resume their office. 18. The society shall form no collections, and, except its records, possess no property- Whatever is laid before them shall be again withdrawn by its owner. 19. The expences of the meeting shall be defrayed by the contributions of the members present. 20. These regulations shall remain unaltered for the first five years. After the reading of the laws, and the list of members already arrived, the rostrum was occupied by Professor Struve from Dorpat, who delivered a long oration on the history, the _ importance, and the present state of astronomy. After mag- nifying astronomy above every other science that either was, is, or ever will be cultivated, he adverted to its history during the last hundred years. From this review he concluded, that during that time the main advancement of astronomy was due ‘to Germany ;—that at the present day Germany cultivated it most assiduously, and made the best astronomical instruments, —a circumstance we are supposed to acknowledge, by engaging Repsold of Hamburgh, (whom they dignify with the name of immortal Repsold,) to furnish a transit instrument for the 220 Mr Johnston’s Account of the Edinburgh Observatory ;—that after Germany Russia came next as a patron of astronomical science, by the building and equipping of observatories ;—then follow England and Italy, France being lowest of all, having only two observatories at Paris and Marseilles. This discourse was neither judicious, nor, I believe, in general well received. No one science needs now-a-days to be exalted at the expence of others. Every man naturally ranks highest that particular branch of science to which he has dedicated himself; but he cannot expect to take other men along with him when he depreciates the departments to which they have with equal ardour addicted themselves. Nor is it necessary to drag in every name to exalt the scientific character of one country above that of other countries. Grant- ing, as Sir James South has done in the Literary Gazette, that Germany deserves better of astronomy than England does,—yet why claim for that country the honour of names and labours which other countries will not concede ?—* Why claim for Germany,” said a Polish professor to me, ** men’ who were countrymen of mine?” And though the Herschels, we may add, be of German extraction, their labours at least are English. Professor Wendt‘from Breslau followed next, and read a memoir on Animal Magnetism. Of this paper there were va- rious opinions. Some thought it very wonderful and very in- teresting,—a greater number thought it all sheer nonsense and delusion,—and some did not scruple to call the man a fool. ‘“< Tf the twentieth part of what he told us were true,” said an eminent individual to me, ** I would forgive him.” But Wendt is known as one of the first medical men in Germany, and the author of many valuable medical treatises, of which I have a list before me of eleven published between 1803 and 1826. He professed himself to be no magnetiser, and therefore many thought him not only as a competent judge, but, as a man of honour, entitled to some degree of credit, when he related merely the effects he had seen exhibited through the agency of third parties. But no man will believe, nay can believe, the marvellous effects of the mysterious influence said to be evolved during the manipulations of this science, unless he have seen them with his own eyes; and yet it is hard to brand honour- Meeting of Naturalists at Hamburgh. 221 able men, who affirm they have witnessed them, with the epi- thets of fool and deceiver. Believers in the science are not fond of talking it over with the uninitiated ; but, among the medical men of Germany, there are many secret converts who are only withheld, by the fear of ridicule, from openly avow- ing their faith. One of these I met with—an individual who had in ote instance magnetized a patient—and certainly the details Of the case were very extraordinary, and some of the more striking features of it attested by other medical men he had called in as witnesses. But he spoke of the power of mag- netizing as a secret and almost sacred power of which he un- derstood nothing,— which he had never employed but this once, though with succéss,—and which he never would employ again, except im some case of urgent, and otherwise hopeless, neces: sity. Whien one cannot assent to statements which appear im- eredible only, perhaps, because we have not had the same evi- dence of the senses as has brought home conviction to others, we ought at least to treat the judgments of honourable men with some degree of respect. These two orations, followed by some announcements re- specting future proceedings, closed the business of the first pub- lic sitting. 'The members then retired, the mineralogists, the botanists, the zoologists, &c. into separate apartments cotinect- éd with the great hall, that the sections might be constituted, and choose their presidents. Berzelius was elected president of the chemico-physieal section, and, on his declining; Pfaff was named in his stead, and Oersted, who had presided over the same section two years before at Berlin, took the oftice of secretary. The mineralogists chose Mons. von Struve, Rus: sian minister to the Hanse ‘Towns, to preside, and Mr Hart- man of Blankenberg in the Hartz to be secretary. Counsellor Sachse from Ludwigslust in Mecklenburg Schwerin, was ap- pointed president, and Dr Schmidt of Hamburg, secretary of the medical section. Dr Mertens of Bremen took the chair among the botanists; and Dr Siemers of Hambttre officiated’. as secretary. The zoologists adopted a more liberal, and per." haps a more considerate, plan. ‘They chose Dr Leuckart of Hei-: déelberg for secretary, and agreed to name a daily president, Professor Fischer of Moscow being appointed to preside at NEW SERIES, VOL: IV. No. 11. APRIL 183]. P "~ < 222 Mr Johnston’s Account of the their first sectional meeting. These preliminary arrangements being made, we adjourned forthwith to. the Apollo Beak to dinner. As the first public day, this was one of the great days of the feast, and, but for the ‘bustle, and confusion, and crowding, andthe impossibility of procuring seats near those of your own science, or with whom you wished chiefly to converse—to which inconveniences I have already alluded—it would have been a delightful entertainment. The dinner was good and plentiful, the music from the orchestra was excellent, and a score or two of amateurs had lent their voices for the occasion, and, seated at one of the long tables in the middle of the:room, entertained us during the entremets with some of their best German songs. Among these “ Was * ist des Deutschen Va- terland ?” was sung with great spirit,—a truly national song composed by one of their great poets called Arndt,—to use the language of a party of young Swedish students with whom I once spent a merry evening at Upsala. They had been singing our ‘* God save the King,” which is a great favourite in Sweden, when one of them remarked to me, “ the song,” I think, ‘‘ was composed by one of your gr cat poets called Brown.” This evening again the soirée was thinly attended, it hav- ing been announced that a new prologue in honour of the Naturforscher was to be delivered in the Theatre, and that tickets, as before, might be had at a reduced price. 19th.—This day being Sunday, there were no public meet- ings; but it had been previously arranged by the office-bearers, that it should be spent in an excursion of seven or eight miles down the Elbe. The Booths, two young Scotchmen, proprie- tors of a large botanic garden and nursery grounds at Flott- beck in the Danish territory, five miles from Hamburg, had handsomely invited the whole body of Naturforscher to stop in passing, view their gardens, and partake of a dejeuner a la fourchette, from which we were to proceed to the grounds and gardens of Mr Bower, occupying one of the finest and most romantic. situations to be met with on the banks of the Elbe. ..* The reader will! find this song with an English translation towards the latter part of this paper. Meeting of Naturalists at Hambrar gh. 223 To see “thiebe grounds is a favourite Sunday excursion with the Hamburgers, to whom they are thrown open on that day on | payment of one merk, about 15d. From this charge the Naturforscher were on the present occasion to be exempted. At half-past nine a. m. the Naturforscher might be seen making their way from all parts of the city to the Nicolai Kirchhofe, where the Polizei had provided a large assemblage of carriages of all des¢riptions, droshkies, barouches, and . open holsteins to convey the party, and, to prevent imposition, had already fixed and intimated the fare, (2 merks) which each person was to pay, for ‘the entire excursion. ‘Thus as they arrived they formed themselves into parties, and each party — put in requisition the carriage which suited them best, paid — their merks in advance, took note of the number of their vehicle, to prevent confusion on the return, and drove off merrily to Flottbeck. It was a fine morning, and the entire day continued delightful—a charming contrast to the perpetual ° ‘rains which rendered almost every day disagreeable in Ham-’ _ burg during the past summer. All: this on a Sunday in — Germany is mere matter of course, and, therefore, nobody made a the slightest remark on the subject, either as regarded our- _selves or the troops of men we passed here and there busily repairing the roads. . It.was a fine sight as we drove along the rich and cultivated country, with here and there pleasant grounds and country houses, and an occasional | peep of the Elbe on the left, spark- . ling through the trees—to see a long line of open carriages of all descriptions, —interminable before and behind, crowded all ‘with happy faces, enjoying and ‘anticipating enjoyment, with ladies head dresses appearing now and then—a sort of point de vue, among the dense grove of hats—and throwing a still more cheerful air over a scene which merry hearts, a bright sun, and a fair land, contributed all to enliven. The garden of the Booths proved well deserving of a visit, and the breakfast was arranged and went off in a style, not only highly creditable to themselves, and, as we Britons thought, to their country, but to the satisfaction and admiration of ‘all present.’ The garden is very rich in plants of all countries, cultivated for sale in great numbers. Among these were 224 Mr Johnston’s Account of the reckoned 12 species of Dryandriz, 30 species of Banksiz, '70 varieties of Camellia, near 400 of Pelargoniz, and 800 of roses, making alone many thousand specimens, arranged ac- cording to the natural orders. The nursery was equally rich in trees of every description. The hot-houses, Kalthauses as the Germans call them, are extensive, one of them glazed on both sides, being 200 feet long. One of the greatest cu~ riosities exhibited was a model of the Rafflesia Arnoldi, taken from the well known cast in the possession of the Horticultural _ Society of London, and which deservedly attracted universal attention. The Booths gained great eredit by their attention to the Naturforscher, and it is to be hoped that their repeated — kindness to the botanical section will only make their esta- blishment better and wider known, and secure it more ex- tended patronage. After an hour spent at Flottbeck, we drove again in caval- cade four miles further to the garden, or more properly the ornamented grounds of Mr Bower. The walks here were de- lightful, and laid out with great taste; and the view of the Elbe from the rising grounds was one of the finest which the banks of the river any where afford. An ornamental tower and Chinese pagoda, erected on two elevated spots, and com- manding a fine view, were objects of great attraction to the party; but on repairmg thither, we found ourselves, with the majority of our friends, shut out. Mr Bower chose to open them only to a select few—a prohibition which he regretted when too late, and which, with one or two other trifling things of the same sort, thought to. show more of the narrow-minded- ness of the Hamburg merchant than any one then and there expected, obliterated any slight feeling of obligation we should, otherwise have felt to Mr Bower for the privilege of walking in his grounds. Having separated from my party, and joined some other friends, I found, on repairing to the gate, that I had wearied out the patience of my fellow voyagers, and that the carriage of which I was a shareholder had gone off without me. For- tunately I found three distressed Germans in a similar condi. tion, and after walking a couple of miles, we succeeded in dis- covering their vehicle. ‘This brought usall back tothe Apollo 3 Meeting of Naturalists at Hamburgh. 225 Saal by 5p. in time to take part in the usual feeding ope- rations, which on this day, from many being delayed longer even than ourselves, were carried on more quietly, and with ‘less crowding than on either of the preceding days. The evening, as Sunday evenings often are in Germany, was spent by the nimble ones of the “Naturforscher i in dancing with the fair Hamburgesses; music being provided, and a room fitted up for the occasion behind the dining-room in the Apollo Saal. Each thus had his mode of amusing himself at his own choice—those who chose danced in the ball-room—those who liked tobacco and strong waters partook of their segars and punch in the smoking-room—and those who chose none of these things, betook themselves to a quiet confabulation in the ’ apartments where it was forbidden either to smoke or dance. 20th.—This morning the different sections met to discuss matters connected with their several sciences. They were ar- ranged as follows :— 1. Thesection of mineralogy met from 8 to 10 in the morn- ing, im the house of his excellency M. von Struve, the Rus- sian minister. 2. The botanical section, from 10 to 12 in the morning, in the house of Professor Lehmann. 3. The section of zoology, zootomy, anatomy, and physio- logy, from 8 to 10, in the anatomical hall.of the Kurhaus. 4. For practical medicine, in the Boursen Halle at the same hour—from 8 to 10. . This section had also occasional meet- ings in the evening. §. For physics and chemistry, from 10 to 12, in the audi- torium of Dr Schmeisser. 6. The pharmaceutical section, afterwards formed and pre- sided over by the venerable. Trommsdorf of Erfurt, whose jour- nals of pharmacy have been long known, and his system of pharmacy so much esteemed in Germany, met in the same place from 12 to 1. By this arrangement, had any one wished it, he could not easily have attended more than two sections, except on alter- nate days, and the hours could not have been otherwise or more conveniently arranged. From 12 to 2 was dedicated to seeing sights—visiting the hospital and other institutions, or 226 he Mr Johnston’s Account of the examining collections, and was the only leisure time that could he so employed.. ‘At two o’clock the general public meeting took place in the Boursen Halle—at four, dinner was in. wait- ing at: the Apollo Saal—and again between dinner’ and the evening reunion, you might have an hour or two to. at ai of for any purpose of your own. It is not my intention to give any detailed account of the proceedings of the several sections. . For'this no one individual can be qualified, simply because it is impossible for him to be present to witness them; and a mere list of papers read, and subjects discussed, which forms the substance of the report drawn up by the secretaries of the sections, would possess little interest for:the general reader. In the Isis only are these pa- pers given at any length; but Professor Oken possesses ad- vantages over even the secretaries of the sections, in the wil- lingness of every one to furnish copies or abstracts of their pa- pers to the father and founder of the society. , And though much interesting matter is at times brought:before the sections, yet the communications thus made, form neither the main ob- ject of these yearly assemblies, nor the most important of the — benefits to be derived from them. Men learn to know,-to esteem, and better and more justly to estimate each other— jealousies are removed—friendships are formed—and thus personal rivalry—harsh. language and controversial sparrings are diminished in philosophical writings; ‘ for you cannot,” said Oken to me, ‘ so harshly speak of ,or condemn in so un- qualified a manner the theoretical speculations or experimen- tal results of a man with whom you haye held agreeable per- sonal intercourse, as we are too prone to do of those whom we have never seen or conversed with.” I attended the mineralogical and chemico- physical sections. The proceedings of the former consisted chiefly in the exhibi- tion of new, rare, or beautiful minerals, and of some. optical instruments by Professor Marx. Few papers were read,-and of these few some were unworthy of the place. Among these was one on primitive formations, by Menge, the well known - mineral-dealer from Lubeck, who had also, by some means or other, contrived to convert the place of meeting into a shop for the sale of minerals. . Meeting of Naturalists at Hamburgh. a The chemico-physical section was more worthy of the time d plac a ~ Atits meetings many interesting notices were given, and a few important subjects discussed. There also, however, eather lengthy specimens of trash were inflicted upon us, ecially towards the end. Most of the time, indeed, was taken up by inferior men, as is to be expected where they form ‘0 decided a majority. - The botanists, I believe, went on very smoothly.. They are an enthusiastic class of men, and captiousness or feelings of personal dislike probably discover themselves less frequently among them than many other tribes of naturalists. There is little in their science, indeed, to call such forth,—it is all beau- tiful,—a roaming among flowers,—and requiring little deep thought, few disappointments are met with in the study, and something more than the science, therefore, is to blame when a botanist’s equanimity is disturbed. - The zoologists (in number 52) also, from all I could learn, were generally well satisfied with each other, and with their labours. The only case of discontent or dislike with the pro- ceedings of which I am aware, was that of Professor Leuckart of Heidelberg, the secretary of the section, who fretted him- self, and endeavoured to disturb others, about a matter in which he should rather have cheerfully acquiesced. ‘To this I shall have occasion to advert when I come to speak of the proceed- ings of the last public day. : The medical section was the most numerous, and the dis- cussions occasionally assumed a very animated character. The great amount of business made it necessary to have occasional meetings in the evening. There, too, as in the other sections, some papers would have been willingly dispensed with; and _ a very general dissatisfaction was expressed, fortunately in the absence of the author, at the double reading, first in English and then in German, of a lengthy paper on the non-contagious nature of the yellow fever, by the only American who attend- ed the meeting. Whatever the merits of a paper might be, indeed, it was rather too much to occupy two hours with it, when the whole time the section could command for transact- ing all its affairs could hardly exceed twelve hours: When alluding to the yellow fever, I cannot help jotting down a very 228 Mr Johnston’s Account of the good New York pun told me by Dr Jamieson of Baltimore, the author of the above paper. ‘ A countryman walking along the streets of New York, found his progress stopped by a close barricado of wood. ‘ What is this for,’ said he to a person in the street. ‘Oh that’s to stop the yellow fever.—‘ Aye! I have often heard of the Board of Health, but I never saw it before.’ ” Of the pharmacologists I heard nothing. Under their pre- sident, Trommsdorf, they discussed tinctures and electuaries; and people seemed to think it was soon enough to have to do with them when they could no longer do without them. In the Boursen Halle, at two o’clock, Professor Oersted of Copenhagen first addressed the meeting, in a long discourse on the application of mathematics to physical science. Of Oersted I have given some interesting notices in a former paper on the “ Scientific Men and Institutions in Copenha- gen.”* JT shall here add a slight sketch of his career. In 1799, he took his degree of Doctor of Philosophy, and the fol- lowing year began to lecture as a privatim docens on metaphy- sics, to. which his mind retains still a decided inclination. In the same year, he was named Adjunctus Lector of pharmacy in the medical faculty. The three following years he spent in travelling through Germany, Holland, and France, and re- turning in 1804, began to lecture on physics and chemistry. The history of the chair of physics in the university of Co- penhagen is rather curious. In 1736, it was suppressed by Christian VI. and an additional professorship of Divinity instituted in its place. At the same. time it was ordered that a professor of medicine or mathematics should give lec- tures on physics. Accordingly, Professor Krutzenstein of the medical faculty gave lectures for thirty years, and dying in 1795, was succeeded by Aasheim, also professor of medicine, who died in 1800. Professor Bugge of astronomy was then ap- pointed to lecture on physics, and in 1806, Oersted was ap- pointed professor extraordinarius, In this year Zeise, now professor of chemistry, became his first pupil, and under his care commenced a. course of study, which, afterwards extended and completed in France under Chevreul, promises at no dis- * See this Journal, New Series, Vol: iii. p. ¥. Meeting of Naturalists at Hamburgh. 229 tant period to yield him a reputation honourable alike to him- ccf, to his talented instructor, and to the university of which he | ‘is a member. Besides his lectures on physics, his proper de- partment, Oersted has at different times lectured on chemistry, principally on general principles, or what he calls the philoso- phy of chemistry, and on electro-chemistry, and his lectures have been much esteemed and numerously attended. The heir-apparent, Prince Christian Frederick, has frequently ho- noured him by his presence, and he has also lectured in Ger- man and French to the diplomatic body. The Society for the Diffusion of Natural Science founded by Oersted, and patronized by Prince Christian, has organized a system of popular lectures, not only in Copenhagen, but also in other towns of Denmark. These lectures in the capital ave delivered by Oersted, Zeise, and Forchhammer, are open to all, and command an attendance of 60 or 80 auditors. Oersted’s experimental are far more valuable than his theo- retical memoirs. “ I] fait des belles experiences,” said a Ger- man doctor to me, “c'est ce qu'il fait bien—mais quand il ecrit— nons ne trouvons ordinairement que des phantasies.” ‘This ex- pression is no doubt much too strong; but it shows the general opinion of his tendency to speculation. To Oersted’s philosophical memoir succeeded a sort of non- descript essay on the tides, by Professor Willebrand of Giessem He laboured to show that the theory of lunar attraction was not sufficient to account for the phenomena. He considered them to be caused by some unintelligible principle of cireula-- tion, which he invited the members to discuss with him in the section, or in the steam-boat, during a proposed trip to the island of Heligoland. But I believe most people were so per- fectly satisfied with what they heard from himself, that they never thought of introducing it in the physical section; and on | board of the steam-boat, most of the in/anders found themselves so much occupied with another kind of circulation, that they had no leisure to attend to that of Professor Willebrand. _ Professor Pfaff, of Kiel, next came forward, and in an ex- tempore discourse of a lively, humorous, and interesting kind, spoke of the application of chemical analysis to vegetable sub- stances of cvery-day consumption, adverted then to the pecu- 230 Mg J ohnston’ s Account of : the liar principles fonds in coffee, a substance so generally nest and exhibited some beautiful pure white crystals of caffeine, which he recommended to practical physicians as likely to prove valuable in.medicine as a mild febrifuge. He exhibited also a new caffeic acid which exists. in the coffee in combixiation with lime and magnesia, and to which is owing its peculiar aromatic smell. ‘This address, enlivened with many witty remarks, gave general satisfaction, being intelligible, not only to all the mem- bers, but to the auditors, male and female, who crowded sk galleries. ° Caffeine is generally supposed to be a discovery of - Pelletier, but its true discoverer was Runge, a-young professor of chemis- try at Breslau in Silesia. Several years ago this young man published a book, in which he described various new principles obtained from vegetable substances, and, among others, also from coffee ; but the book was written in so peculiar a style that very little attention was paid to it. The substances described were also often impure, so that the properties he attributed to those which he obtained, are not always to be found in the purer substances since prepared by others ; yet still the honour of the several discoveries, and of making the first steps in this inte- resting field, is due to Runge ;—he should not, therefore, be for- gotten in the history of the science. Runge was at the meet- ing in Hamburg, which, I believe, is his native place—a true specimen of the German student—long lank hair—a careless free manner—fond of his pipe, his friend, and his bottle of beer. He exhibited in the physical section, the results of a long-continued and elaborate examination into the chemical na- ture of various natural orders of plants, gathered in the differ- ent months of the year, and their reactions with the metallic salts, those of copper, tin, iron, bismuth, lead, as shown in their colouring powers upon cotton cloth. ‘The changes that take place in the juices of plants from the first months of spring to_ the end of autumn, as exhibited in the change of their colour- ing properties, was very striking and very interesting. The dinner to-day was crowded and uncomfortable. A di- version was created after we had finished our coffee by a ery of fire; and curiosity led many even of the Naturforscher to thé spot. It proved to be a large building in the centre of the city, Meeting of Naturalists at Hamburgh. 231 which was entirely SI The regulations for fires, as they must necessarily be in so crowded a city, are very strict. : double guard is called out, and none are allowed to approach the spot. ‘Should any one contrive to force his way in, a bucket is immediately put into his hand, and he is set:to work: _ 2ist.—On the breaking up of the sections to-day at’ noon, | alll the Naturforscher adjourned to the botanic garden to partake of an elegant dejeuner, prepared at the expénce of the good. city of Hamburg. The breakfast at the Booths had no doubt _ given occasion to this,—the city could not be out-done by two private individuals. On a pleasant slope facing the city, and having hot-houses on either hand, were erected two large tents, gaily and tastefully ornamented with flowers in festoons, and gar- lands of all descriptions, in which were’set out two long’ tables groaning under eatables of every kind and flavour, pleasing at once to the eye and the palate, and liquids of every strength from the French eay de vie to the lightest claret. The one tent was monopolized by the ladies, the botanists, and the zoologists ; 3 the other, into which I happened to stroll, was the resort of the heavier, but not the duller, men of the mineralogical and phy- — sical sections... Not that this separation was strict ; it was only general, and probably accidental, for we had with us Cliamisso of the botanic garden in Berlin, a poet, botanist, and traveller, who accompanied the expedition of Kotzebue round the world, a most: amusing, witty, and cheerful man... After a short time, the champagne began to flow among us, and presently came the drinking of toasts, and hobnobbing, and making: of ‘speeches, and bandying of wit, and roaring of laughter, to such a degree that the sober ones wondered, and the merry ones came to share, if possible, in the amusement. Pfaff and Chamisso were the leading men in this display of wit and humour.. And though some of the grave ones shook their heads at what they were pleased to term ‘our riotous behaviour, yet I look back to that hour as one of the happiest I spent in Hamburg. The botanic garden of Hamburg is in high order, and does much credit to Professor Lehmann, who superintends, and has formed it. It was established so late as 1821, and is already one of the richest in Germany. Dr Lehmann gives lectures on botany, and Oldendorf, the managing gardener, has a school of 232 Mr Johnston’s Account of the practical. gardening—a species of institution which might very well be connected with our botanical gardens in this country. It would not only train up a race of practical gardeners well in- structed in botany, but might also be so managed as to cause not only a material saving, but probably an actual increase to the funds of the institutions. Two o'clock p. mM. saw us again assembled in the Boursen Halle. Dr Simon of Hamburg first addressed us in a long prosy oration in praise of natural science and medicine, which was by no means well received. It is a pity that the office- bearers should not have some controlling power over the papers brought before the general meetings, that a proper and worthy selection might be made to be read in public, that men of talent might not be condemned to sit by hundreds, listening to delira- tions spun out by the hour, and by men of no reputation; while at the same time they have the mortification to think that such exhibitions go forth to the world as specimens of what so grave, and learned, and philosophic a body can do. I have spoken of the general simplicity of the Hamburgers in matters of science ; and yet, even among them, I learned after the meeting was over, that the impression had gone forth, that the transactions of the public sittings, to which only they were admitted, were in gene- ral unworthy of a society of such high pretensions. A similar idea seems to have entered into the mind of Tiedeman, for, at the meeting in Berlin.in 1828, he proposed that such a power of selection should be intrusted to the office-bearers and certain others. After a long discussion, however, the motion was ne- gatived by a small majority of eighteen, it being supposed by many to interfere with the general liberty and equality of all. Next came on the appointment of the place of meeting in 1831. The subject was introduced by Count Sternberg of Prague, who expressed the wish of the imperial government, that the society should assemble in the ensuing year at Vienna. After some little discussion this was agreed to, and Baron Jacquin of Vienna was appointed to the office of president, and Von Littrow to that of secretary. I have repeatedly spoken of presidents ; but “ we have no presidents,” said Oken to me ; ‘no man above another. We are all on an equality ; we have a first and second geschifisfuhrer, es ¥ "Meeting of Naturalists at Hamburgh. 233 ~~ to oli hs business for us, but it is no elevation.” —“ It is | e of which another need be jealous,” said a botanist to me ; «6 the newly, appomted geschiftsfubrer feel, I daresay, nothing elevated.” So it is the custom of some to talk of these official situations, and yet it is a high honour nevertheless,—and an honour to be proud of,—and one which is felt as such, as well by those on whom it is bestowed, as by those who think them- selves unjustly passed over. And, disguise the name as we may, in what age, or in what country, would it not have been an object of ambition—a laudable and praiseworthy object—to preside at the meetings, and to direct the deliberations of four or five hundred of the most learned and intelligent men of the time ? : These meetings were for some years an object of jealousy to the German rulers, and their proceedings were carefully watch- ed during several successive anniversaries before they paid them any outward attention. Learned professors, it is said, were sent to the assembly, not as spies of course, but merely to bring home intelligence from so interesting an association! ‘The minister felt much interested in the advancement of scientific intercourse, and was anxious to hear what passed at these large assemblies. If his friend, Professor --——-——, would like to go, he would procure him a grant of money to defray his ex- pences. ‘The professor, a man after his own heart, jumped at the proposal, went to the meeting, and came back eagerly to sa- tisfy the minister’s amiable curiosity. One hears such stories occasionally when sitting éte-d-téte with a German naturalist, during the intervals of puffing a segar, or sipping a glass of punch ; but it is chiefly the young men who are indiscreet enough to tell them, not having yet experienced how necessary it is to have the fear of arbitrary power continually before their eyes. That the German rulers now patronize these meetings, is an evidence that their former jealousy was without foundation, and that science alone is sought to be promoted by these comings together. Yet even now a species of unfelt, perhaps, yet never- theless, real control and surveillance, are exercised over them by the governments of the places to which they are invited. The king and his ministers agree to invite the meeting to their 234° Mr J ohnston’s Account of the chief city ; “ but we must ais professor so-and-so for presi- dent, and Dr so-and-so for secretary, and then we can keep all things right.” Accordingly, a deputation of three or four per- sons is sent to the meeting—they deliver. their commission— and, having made, out a good case, the thing is agreed: to. Then one of these men gets up and proposes another of them as a fit person to be president—a third rises and suggests that the last speaker be appointed secretary, and the matter is carried of course ; for, besides the delicacy felt in regard to per- _ sonal opposition, it is understood that these individuals have the confidence of the government, and will be able to do most for the reception and- entertainment of the assembly. pea The president and secretary have the sole and entire disposal of all the time of all the members during the appointed days of meeting ; he who guides the president, therefore, moves all the others like so many puppets. Such control isthe necessary , consequence of their connection with, or dependence upon, men — in power, where power is regulated and checked by no consti- tutional law. So long as they met in small cities as an indepen- dent body, unaided and unnoticed by those whom political power or wealth only had made great; they had a perfect control over their own “ sayings and doings.” But the German princes have found a sure way of taming the lion they feared when he arose ‘among them shaking his mane ; they have thrown him a sweet. sop, and he has swallowed it, and laid him down to sleep. For. the sake of mere natural science, perhaps, it is as well that it should be so; but why should men of science be gagged ?—the lights of their age set “ under a bushel ?”—that they shall be permitted to congregate in this or that city, but shall be forbid- den to hold colloquy on subjects the most intimately connected with the welfare of their race? Such restraint is not heard of or seen, yet it is secretly felt and laboured under by all. A natu- rally open or bold man, in some ‘moment of excitation, shakes it off; but when he cools down, he feels surprise at once, and regret for his momentary rashness, sensible that now he has sub- jected himself to a suspicion that will cling to him for years, retard his advancement in life, and follow him’wherever he goes. In illustration of this, they tell a story of Prince Metternich or Mitternacht, (Midnight,) as the punsters call him in Ger- Meeting of Naturalists at Hamburgh. 235 many. The Emperor, it is said, heard often, aid” saw many counts of these mectings, and expressed: his surprise that they were not resorted to by men of science from Vienna. One of the maps engraved for the use of the members, and containing only the names of the places from which individuals had come to the meeting, was brought to him, and he was nettled that his capital was not even mentioned in it. Supposing it to be the want of funds which kept his professors at home, he inti- mated that funds should be provided from the treasury for de- fraying their expences. On.the. approach of the next meeting, accordingly, several individuals applied for passports to the director of police. ‘‘ Well, Doctor, you want a passport ? What are you going to do at ?”—** T am going to the Naturforscher Versammlung.”—“Oh, you are going to this meet- ing, too, are you? But what do you think the minister will say to it? You know he dislikes all these meetings.”"—“* He can have no objection surely, when his majesty has expressed a wish that we should»go, and has granted money to defray our ex- pences.”——“‘ Very true, very true, but I would recommend you to think better of it. You may have your passport if you choose, but I would advise you as a friend not to go. You are a candidate for so-and-so, and you are very likely to have the appointment ; but, should you give offence, “ —* Jl est comme un Roi ce Mitternacht,” said a Halle man to me. , This story I have heard repeatedly, and it does not appear at all incredible ; but whatever may have been the former feel- ings of the court and ministry of Vienna in regard to these meetings, it is certain that every thing will be done in Septem- ber next to make the anniversary of 1831 an era in the history of the society. After the nomination of the office-bearers, a discussion arose as to the most proper way of announcing to learned men the place of meeting, &c. for the ensuing year,—whether by parti- cular and private letters from the president and secretary, or by general and public announcement. ‘This matter was at length entrusted to the discretion of the geschiiftsfuhrer. It had been announced at the meeting of yesterday that, for the entertainment of those chiefly who, living in the interior, 236 Mr Johnston’s Account of the might never have seen the sea, or sailed. down the Elbe, a trip to Heligoland had been projected; and that the Rotterdam company had placed a large steam-boat at their disposal for this purpose. To-day, it was intimated that those who intended to go must be on board by five o'clock to-morrow morning; and that there would be no public or sectional meetings for the three days it was intended the party should be absent. This announcement gave to many great dissatisfaction. It was kind- ly meant by the directors, but it was injudicious thus to separate the Naturforscher into two bodies; and, for half the time they were to be in Hamburg, to prevent them from holding com- munion with one another. Not more than half the number of strangers availed themselves of the opportunity of seeing the sea; and meanwhile the other half were left to employ them- selves as they might. But the true in/anders rejoiced at the proposal, and .it was amusing to hear their grave and earnest inquiries about the nature and mode of operation of the see krankheit they had so often heard of, and were now destined to experience. The party sailed the first day to Cuxhaven, where they spent the night uncomfortably enough I believe ; the second was spent in Heligoland, and they reached Hamburg again on the third day. ‘There were few who on their return could not speak feel- ingly enough of the sce krankheit ; and some found one day- on shore little enough to restore them to their propriety. I did’ not accompany ‘the expedition, but Professor P . of Edin- burgh, has furnished me with the following lively account of the sufferings and privations it had to undergo. *¢ It would require a better memory or a more poetical imagi- nation than mine, to infuse interest into an account of the éx-’ cursion to Heligoland, or make it worthy of any but a very brief notice. Scientific interest it had none; for though we had Enke and Moll on board, and other less distinguished As- tronomers, the bearings of the rock we were bound to had al- ready been laid down too accurately, to give them even a pre- text for making new observations: and the Geologist, though he might pick up from the needy natives a few cornua ammo- nis and belemnites, had little to glean, by his own industry, in the mass of loose friable sandstone, deeply tinged with a ferru- Meeting: of Naturalists at Hamburgh. 237 d, which composes the island. And what could the st do, where the greatest variety, in his way, was the nor’s cow—sole specimen of the genus Bos to be found in sland. The Botanist, indeed, if he happened to be one mediterranean Naturalists who. had never before one the sea, was evidently filled with astonishment at those wonders of the vegetable world which you regard at Portobello with such stoical indifference ; and loads of sea tangle and fuct are, I doubt not, now reposing in glass-cases in the interior of Germany, differing in no respect from those which we barba- rously burn into kelp on the shore, or spread over our fields as manure. “‘ Nor can I say that the social pleasures of this expedition quite compensated for the want of scientific interest. A steam- boat is not the best place in the world for making or cultivating new acquaintances, particularly where the majority of the party are Germans, and without any infusion of French vivacity ; and when many of those best able to amuse and instruct were at one time suffering from the nausea of a first voyage, at another frightened out of their propriety by a breeze of wind and a swell of the sea, which must have been alarming enough to novices. Nor was there much on shore to make us forget the lugubrious aspect of things on deck. For want either of previous arrangement or of fit accommodation on the island, the party, which might amount to seventy or eighty, did not meet to dine together, but were scattered, in little knots of ten or twelve, often strangers to one another, over all the houses, private and public, of the village. ‘This, I believe, was generally felt as but a poor compensation for the roar and merriment of the Apollo Saal at Hamburg: for though, even there, you and I may have missed those after-dinner speeches, which, in our country, do sometimes nobly redeem the clatter of knives and forks, and give an intellectual character even to a city feast, yet there was much to prize in the joyousness, good humour, and mutual kindliness that seemed to animate the whole com- pany. Nor shall I readily forget the energy and intensity of feeling with which the songs, whether Bacchanalian or Patriotic, were sung in this assembly of savans. One of the latter class of songs pleased me so much, that I amused myself, during the NEW SERIES, VOL. IV. NO. IL. APRIL 1831. Q 238 Mr Johnston’s Account of the dreary parts of the naval expedition, with turning it into hob- bling rhymes. The original, however, I must say, is not much better, as far as the verse is concerned : it was the thought, and the enthusiasm it excited, rather than the measure, that delighted me. I send you the original to remind you of it, and add my own version. Which is the German’s Fatherland ? Swabia, perhaps, or Prussia’s sand ? ; Where on the Rhine the wine-fiood streams ? Or round the Belt the sea-bird screams ? Oh no! not so:—an ampler space The German’s bounding line must trace. Which is the German’s Fatherland ? Is’t Pomerania’s barren strand ? —Where “ Munich all her banners waves ?” —Or Time and Conquest Austria braves ? Oh no! not so, &c. The German’s country shall we seek Where climbs the, Swiss the Glacier peak ? Where high Tyrol her mountains piles ? Or Stiria’s Alpine desert smiles ? Oh no! these countries please me well, But German land must mightier swell. Where then can be this Fatherland, That knits its sons in filial band ? What is the silken cord that binds In mutual love so many minds ? “‘ Where’er is heard the German tongue, ** And German hymn to Heaven is sung, « Whate’er the clime—the kindred—be, “ That land—that land is Germany.” Then blest be thou, from age to age, Land of the Hero, Bard, and Sage ! Still loyal be thy sons and true, Worthy the stock from which they grew ! Still foremost to pronounce the vow, With fervent hearts, as we do now, (Recorded let it be on high) For Thee to live, for Thee to die ! * * Was ist des Deutschen Vaterland > Ist’s Preussenland ? Ist’s Schwabenland ? Meeting of Naturalists at Hamburgh. 239 s brought you back to the Hall of Apollo from which you were lucky enough not to be ba-» 2d. This sai I shes with Dr Trail i in a visit to Harburg, n the Hanoverian side of the Elbe. We crossed over in a > tn which plies regularly ; and after wandering for some hours among the sand-hills beyond the town, collecting flints with impressions of shells, and other organized substances, which are by no means rare, we were brought back again to Hamburg Ist’s, wo am Rhein die Rebe bliiht, Ist’s, wo am Belt die Méve zieht ? ‘O nein! nein! nein! Sein Vaterland muss grdésser seyn ! Was ist des Deutschen Vaterland ? Ist’s Baierland? Ist’s Steierland ? Gewiss, es ist das Oesterreich, An Siegen und a an Ehren reich ! O nein, &c. Was ist des Deutschen Vaterland ? Ist’s Pommerland ? Westphalenland ? Ist’s, wo der Sand der Diinen weht ? Ist’s wo die Donau brausend geht ? O nein, &c. Was ist des Deutschen Vaterland ? So nenne mir das grosse Land ! Ist’s Land der Schweizer? Ist’s Tyrol ? Das Land und Volk gefiel mir wohl ! . Onein, &c. Was ist des Deutschen Vaterland ? So nenne endlich mir das Land ! * So weit die deutsche Zunge klingt “ Und Gott im Himmel Lieder singt ! ** Das soll es seyn ! * Das, wack’rer Deutsche, nenne Dein !” ‘ Das ganze Deutschland soll es seyn ! “Te O Gott vom Himmel, sieh’ darein, ; Und gieb uns achten, deutschen Muth, Dass wir es lieben, treu und gut! Das soll es seyn ! Das ganze Deutschland soll es seyn ! 240 _ Mr Johnston’s Account of the’ by six o'clock in the evening. One curious circumstance I may mention in regard to the sand-hills around Harburg. Here and there among the brown sand occur small white spots of two or more feet in diameter, which are carefully dug out for house- hold purposes. These spots penetrate the hills to a consider- able distance, like large solid pillars, and they are followed in the process of excavation by shovels with handles ten or twelve feet long. ‘The only one I saw in the act of being dug out was inclined to the horizon at an angle of perhaps 50°; but I did not learn whether such be their general directions. It would be difficult to assign any satisfactory reason for these singular deposits. The soirée in the Apollo Saal this evening was quiet and pleasant, and I spent a couple of very agreeable hours with Pro- fessor Berzelius of Stockholm. 23d. The sections this day met as usual, having agreed, on seeing their‘own strength yesterday at dinner, to resume them even during the absence of the Heligolanders. In the chemi- cal: section Professor Pfaff endeavoured to show that the gene- rally received theory regarding the developement of electricity by induction is erroneous, and that of two. conductors brought near each other, if the first be positive, both extremities of the second are positive also. I regretted very much that I could not follow his language on this very interesting and very im- portant subject, which the experiments of Biot were supposed formerly to have settled, but on which those present best quali- fied to judge were inclined to agree with Pfaff. It is to be hoped that a memoir on the subject may before this time have been published by him in some of the German journals. The tower of St Michael’s Church was to-day a place of con- siderable resort. It is 456 feet high, and gives a distant view over the Elbe and the surrounding flat country. No one can have any conception how the city of Hamburgh is packed to- gether, unless he resort to some such elevated spot, where he can look down upon the limited space which daily and nightly con- fines 106,000 souls. ‘This tower of St Michael’s is interesting as the place from which Benzenberg in 1803 made his first ex- periments on the diurnal motion of the earth. But here it is well known he obtained no good results, from the constant pre- Meeting of Naturalists at Hamburgh. 241 sence ‘of currents, which disturbed the true descent of the falling 4 obliged, therefore, to have recourse to deep mines, hich he found that a heavy body in falling actually deviat- mm the perpendicular by a quantity agreeing very nearly h the formula of Laplace. This evening also there were comparatively few at the soirée, and the ladies in the dancing room looked anxiously but in vain for partners, and it was really melancholy to see them all sitting ‘so solitary and forlorn. 24th, The Heligolanders returned this evening, and many of them joined us in the Apollo Saal, but many also found it better to remain at home and recruit. 25th, This was the last day of the meeting, and many per- sons whose time was limited had already gone. The sectional business was entered upon as usual by all parties, and the animal and plant men exhibited the spoils with which their visit to the sea had enriched them. At two the final assembly took place in the Boursen Halle. Professor Fischer read the first address, bemg an account of the botanic garden at St Petersburg. This garden, at present in so flourishing a condition, is entirely the work of Professor Fischer. Before his appointment there was a place called a botanic gar- den, containing at most 600 species. It now boasts upwards of 12,000. From Persia, Caucasus, Armenia, and Siberia, it has received great accessions—while M. Riedel, the botanist who accompanied M. Langsdorf to Brazil, has lately brought home upwards of a thousand living plants from that country. ‘They have been preserved by the method already known in England, of planting them in pots, and rearing them so on the spot where they are indigenous. By this means their preservation is far more effectually secured than when they are dug up in the woods and sent on board before they have had time to take root. Professor Fischer was succeeded by the secretaries of the se- veral sections, who read to the assembly an outline of what had been done in each of the sectional departments. On reading his report of the proceedings of the zoological section, Professor. ' Leuckart took occasion to animadvert in a few ill-natured words on the appointment of Englishmen to preside in that sec- 242 Mr J ohnston’s Account of the tion: “It is the first time,” said he, “ that a foreigner, who did not understand the language, has been appointed to preside _ at a meeting of German naturalists.” I know not what parti- cular spite the worthy secretary could have against either Mr Gray or Dr Traill, the two gentlemen on whom the honour was conferred ; but it was evidently spite, or ill-feeling of a similar kind,—for both of our countrymen knew something of the lan- ‘guage, and even had they not, it would have been only consist- ent with that true courtesy which distinguishes the Germans, but which the professor seemed to have lost on his way from Heidelberg, to have dignified these foreigners, for their coun- try’s sake merely, with this horary honour. The bad taste and bad feeling of Leuckart’s allusion was gene- rally felt, and Dr Siemers, who rose next to read the report of the proceedings of the botanical section, took the opportunity of inserting a few words, which made ample amends for all that had passed. In the name of the botanical section, he then pro- posed that the meeting should send a letter to the East India Company, returning thanks to that body for the munificent gifts of Indian plants which they had made to all the celebrated bo- tanists in Europe, and to pray that Dr Wallich might be al- lowed to remain longer in England, to carry on the work he had begun so splendidly, and which no one was so well qualified to finish. A letter embodying the latter request was also pro- posed to be sent to the king of England, as likely to influence the Court of Directors, and copies of both, as drawn up’by a committee of the botanical section, were read to the meeting. After some discussion, it was agreed to refer the matter to a committee, by whom the letters were ultimately dispatched. It is to be hoped that the Court of Directors will accede to the wishes of a body of men so capable of pronouncing correctly on the merits and labours of Dr Wallich. A medico-philosophico-physico-juridical essay was then read by Counsellor Stierling of Hamburg, and a proposal made by Dr Stintzing, also of Hamburg, for the publication of an Ency- clopedia or Journal of Science by the Society, neither of which gave rise to any observations. The business was now finished, and the President Bartels, after a short address, pronounced the anniversary for 1830 to be at an end. This was the signal Meeting of Naturalists at Hamburgh. 243 for the ew-president, who in this case was Professor Tiedeman Heidelberg, to rise and deliver the usual address of thanks to Po i and authorities of Hamburg, for their kind treat- ment and general attention. ‘This address was received with at applause. _ The dinner table to-day was unusually crowded ; many Ham- burgers had been admitted, and all the adjoining apartments were put under requisition. ‘The music and the songs, and the mere eatable part of the dinner, were of the best description, but nothing could reconcile me to the noise, crowding, and con- fusion, and to the necessity of sitting in a side room, and among men one had never seen before. After dinner some toasts were given, and the only speech I heard during all these feastings was by the lively Pfaff of Kiel, who, after lauding the city and its trade, concluded by proposing, ‘‘ The apothecaries of Ham- burg, who had contrived to change chemistry into alchemy !” The whole affair was finished off at night by a splendid ball in the large room, hitherto devoted to feasting ; and the beauty of Hamburg was all assembled to grace the departure of the Naturforscher. The dancers kept it up till a late hour, while the punch and segar men in their own apartment seemed equally unwilling to break up their pleasant fellowship. But they drop- ped away one by one, and the crowd of scientific men whom Saturday saw squeezing each other in the press, talking loudly, or joining with enthusiasm in the chorus of a patriotic song, were seen on Monday—solitary, silent, and far apart,—scattered to the four winds of Heaven. Such is a general view of the proceedings of the Society of German Naturalists at their ninth anniversary. To me it proved exceedingly interesting. If I have been able to infuse a tithe of this interest into the above account of it, my readers will not regret that I should have spun it out to so many pages. It was said not to have been so splendid as that of Berlin, but this was owing to the locality, not to the members. Of strangers, there came to Hamburg 258,—a number nearly as great as met together at Berlin; and where the chief object is to see and to learn to know men, their presence is sufficient. So I found it, and I shall never regret my visit to Hamburg on this occasion, which gave me an opportunity not only of becoming acquaint- 244 Dr Goring on the Manufacture of ed with many men I had never before seen, but also of meeting with persons I had formerly learned to know and esteem, but whom I might otherwise never have had the pleasure of meet- ing a second time. The first object of these meetings is to promote this acquaint- ance and friendly personal-intercourse among men of science ; but other great and perhaps more important benefits grow spon- taneously out of them. They draw public attention to science and scientific men, and make people inquire concerning both them and their pursuits. They exalt science in general esti- mation, and with it those who devote themselves to its advance- ment; and, above all, they spur on the governments of the dif- ferent states to examine into and ameliorate the condition of their scientific institutions ; and to seek for men of true science to fill the chairs of public instruction. Such and similar bene- fits have already resulted from the meetings in Germany. Might not similar results in our own country be looked for from a si- milar institution ? Portose.1o, 23d February 1831. Art. Il.—Project for facilitating the Manufacture of Achro- matic Object-Glasses for Engyscopes. By C. R. Gortne, M. D. &c. Communicated by the Author. [ am not in the habit of recommending things to the public which have not been thoroughly tried ; nevertheless, I shall venture in the present instance to suggest a scheme of ameli- orating and perfecting combined object-glasses of short foci purely from theoretical considerations. Every optician who has turned his attention to the construc- tion of object-glasses with large angles of aperture, must then have felt, that the state in which it is most easy to produce them is that of over-correctiou, both for sphericity and dis- persion. I have little doubt, that a workman could at once hit off an object-glass in this state as easily as he could the figure of the metal of a reflecting telescope with an hyperbolic curve. T have examined a great number of double object-glasses of Achromatic Object-Glasses for Microscopes. 245 Chevalier’s construction, and many others, and find three out of four to be in the condition I have alluded to, viz. with the ‘too powerful for the convexes, both in point of sphe- rical and chromatic aberration, even with very moderate aper- Now it is known, that, in order to obtain a focal pencil of large dimensions, we are compelled to combine as many as three double object-glasses together. This complication is a neces- sary evil, unless we choose to dispense with seeing the more difficult kinds of lined objects. Moreover, light and aperture are always acceptable, (when not absolutely necessary,) if we examine opaque objects with high powers. Proceeding, therefore, on the supposition, that we must have three object-glasses to have a perfect engyscope, my project consists in supplanting one of the three by a common uncorrect- ed lens of suitable focus, figure, and material, caused to act against the excess of aberration which I suppose to be left in the concaves of the other two. I do not mean to assert that we might in all cases be able to assume two over-corrected achromatics, and then make a sim- ple convex which should be able to neutralize their aberration ; but I think it would be perfectly feasible to assume the convex, and to make two achromatics accommodate themselves to their vulgar neighbour’s humours, if the latter is unable to adapt him- self to suit theirs. In the case of a triple object-glass we see one concave capable of reducing two convexes to a state of com- plete subjection,— Why should not two concaves master three convexes? Indeed, I cannot help thinking myself, that one highly over-corrected double achromatic might be combined with a common lens with vast advantage, and that this sort of triple object-glass might be made equal in power and aperture to two double achromatics, and greatly superior toa triple ob- ject-glass of the ordinary construction in the correction of the direct and oblique pencil, as well as in the aperture it would sustain. See Fig. | and 2 of Plate II. the former being a triple, and the latter a quintuple object-glass of the new construction. It was ever my wish to contrive some sort of object-glass which should of itself, without the assistance of any other, do all that might be required of it; and, with the exception of four or five objects of the lined kind, this sort of object-glass 246 _ Dr Goring on Achromatic Object-Glasses. would perform completely well. The lines on the scales of the Pieris brassice, of the Podura plumbea, and a still more re- fractory species from the King’s cellar at Windsor, together with those on the feathers of some of those small brown moths which infest our clothes, seem almost without any parallel in nature, and have tormented opticians to death to make engy- scopes with apertures capable of exhibiting them, which are in a manner of no absolute use for any other purpose. I think an object-glass with an aperture of about 25°, well corrected, will ‘show any other objects, save those mentioned, which by the by are perfectly visible with any common equi-convex lens of large aperture and short focus, nearly as well as one with an aperture of 50°, and therefore may be considered effective for all ordinary purposes. It must not be supposed that I am insensible to the highly meritorious labours of Mr Lister, who, in his paper on the Improvement of the Achromatic Compound Microseope, * has given us a most splendid example of the extent to which expe- riments, scientifically conducted, may be made to supplant more rigorously demonstrative science; but his method of correction seems to me only applicable to object-glasses of moderate focal length, which do not require to be placed in con- tact, to give room for the application of objects. Mime is pecu- larly adapted to those of short foci placed close together. LamBetu, Nov. 25, 1830. P. S§.—When I wrote the above paper, I had no means of putting my method of correction to the test of experiment ; but having since procured a couple of over-corrected object- glasses from Chevalier, of about ;‘4 of an inch focus, I com- bined them with a common equi-convex lens of crown glass of 1 inch focus, placed in front of them newt the object, and found that this composition was still a little over-corrected, both for colour and spherical aberration with the naked aperture of the glasses. I am persuaded that a lens of a little shorter focus would have produced an exact correction. One of the afore- said object-glasses also combined with an equi-convex lens of plate-glass of one inch focus placed in front gave a very good correction both for colour and spherical aberration, so that I * Philosophical Transactions for 1830, Part I, p. 187. Dr Brewster on the Phenomena and Laws, Gc. 247 think no doubt can be entertained of the feasibility of my scheme ; and, when I consider that the two lenses were the first ; that b ppened to come to hand, and that the curves of the ob- ct s of Chevalier’s construction are all alike, so that no ‘error can well be committed except in the quality and thick- _ ness of the glass employed i in their manufacture, I should hope that the construction of object-glasses for engyscopes will be- come a very simple matter. = Jan. 25th, 1831. Arr. III.—On the Phenomena and Laws of Elliptic Pola- rixation, as exhibited in the Action of Metals upon Light. By Davin Brewster, LL. D.F.R.S. Lond. and Edin. Concluded from last Number, p. 165. Iw order to give a general view of the number of points of restoration, and of the other phenomena which take place after different numbers of reflexions, I have drawn up the follow- ing Tables. Taste I1.—Showing the numbers of reflexions from silver at which elliptically polarized light is restored to a single plane of polarization, with the corresponding angles of incidence, and the position of the plane of restoration in relation to the plane of reflexion, computed for 20 reflexions. (For angles less than the maximum polarizing angle.) Angle of 9 tay Integer Multiples. Restora- tion. —2 2. 44-648—104+12—14416—18+20 71 0 21 2.111'419 : ; . 71 42 Qi 2.125 +17 ‘ ‘ 71 32 2} 2.143 415 71 23 21 2.167 —13 ; a "1 8 Q1 2.200 411 ‘ ‘ 70 48 Q2 2.992 —20 : 10 34 22 2.25 9418 ; - - 70 17 248 Dr Brewster on the Phenomena and Laws . 2 dg Integer Multiples. Testor 10n.- 22 2.986 16 . i : 69°53’ 23 2.38838 +7414 | - - 69 29 22 | 2.375 —19 c bi 69 3 2; 24 —]Q 4 68 59 23 2.498 —17 : 68 33 2325 —5+10—15420 2 67 54 24 2.571 —18 ¢ ¢ : 67 14 SF 26°! “43 : 6 58 22 2.667 —8+16 - 66. 25 2§ 2.714 +419 - - os 66 0 dae one oa | : x 65 45 25 28 —14 , “ 65 23 25 2.833 +17 : 65 9 2$ 2.857 —20 - - 65 0 +3 3 +6+9+412415+18 - 63 43 33 3.167 —19 2 a a 62 29 31 32 —16 : : i 62 15 $1 325 —13 y 61 15 3} 3.38 —10 - ‘ 61 20 $284 17 & c : 60 53 33.85) s Opel 4 e ‘ é 60 15 65.86%) 18 : 59 38 32 3667 +11 2 : 59.13 3% 3.75. —15 ‘ 4 “ 58 42 $$ 38 +19 ‘ ‘ 58 15 —4 40 +48—12+16—20 : 57 16 42 4.25 417 é ‘: 55 54 45 4.333 +13 - - 55 29 4445 —9+18 - - 54 42 42 4.667 —14 i P : 58 54 45 4.75 —19 - : 53 $1 ao ee +10+15+420 ‘ 52 27 51 5.333 —16 : ; E 51 5 515.5 —ll : : : 50 27 52 5.667 —17 : : 49 49 we 6 6 +12—18 : - 48 38 6} 6.333 +19 : : : At 23 of Elliptic Polarization. 249 meee 13... - : : 4G 5 62 6.667 —20 . : : 46 32 +7 7 +14 : 4 ‘ 45 35 mae 7.5. —I15 ‘ : 4418 is 8 +16 : ‘ . 43 0 8185 +417 : . - 41 52 ao 9 “+418 . ‘ . 40 51 91 9.5 —I19 . : . 39 51 =10;10 +20 . i 39 0 e11-11 © “ . . 37 15 ig. 12 . ‘ ‘ 35 50 +13 13 ; ‘ 34 33 —14 14 . ‘ 32 30 +15 15 - “ (8215 —16 16 , , 31 17 +17 17 - : 30 30 —18 18 . . ’ 29 42 +19 19 - . . 28 56 —20 20 : : : 28 10 Taste I1.—Showing the numbers of reflexions from silver at which elliptically polarized light is restored to a single plane of polarization, with the corresponding angles of restoration, and the position of the plane of restoration in relation to the plane of reflexion, computed for 20 reflexions. (For angles greater than the maximum polarizing angle.) No. of Re- Angle of Rasions, Integer Multiples, Ketter —2 2 44-—64+8—10+12—144+16—18—20 73 0 Qt 2111 —19 : : "4 9 2 2.195 +17 - " " "4 18 Qi 2.143 —15 ; : : 74 28 2t 2.167 +13 - a a 14 44 2? 2.200 —I11 ‘A ah bisa "5 O 22 2.292 20 : : J "5 12 Qi 2.956 +9418 ; ‘ t "5 26 22 2.286 —16 : . ; 15 43 22 2333 —T714 ‘ : 16 2 250 Dr Brewster on the Phenomena and Laws | sg shea ane Integer Multiples. Testo 25 2.375 +19 i G - 76°19" -o4: —12 : ‘ ri 16 33 25 2.428 +17 \ , a 225 +5+104+1542 at, 77 13 24 9.571 —18 at . “#0 "7 38 526 —I13 - - 2 2.667 —8+16 ‘ “ : 18 38 Q5 2.714 —19 oy “ . 18 23 23 2.95 +11 i 78 33 2428 —14 : ae 18 47 28 2.833 +17 . : z 18 57 § 2.857 —20 ‘ 3 * 19 4 —3 30 46—9412—15+18 ‘ 19 40 3! 3.167 +19 . : . 80 37 3132 —I6 : : 80 24 31 3.25 +13 3 ee 80 34 3 3.333 —10+20 : 5 80 50 234 —17 . re 81 2 3135 +7414 i 4 81 19 33.6 —18 u : aioe Cae as 32 3.667 —11 U : ‘“ 81 45 5 3.15 +15 - - ‘ Sr oT 3438 —I19 2 t : 82 8 —4 4 +8—12+16—20 i 82 30 4t 425 +17 ~ - a : 82 58 4? 4,383 —13 ‘ ; : 83 16 424.5 +9418 ah . - 83 23 42 4.667 —14 - . . 83 38 54.75 +19 - . - 83 45 bok. & +10—15+20 . 2 84 5 5}. 5.338 —16~ 5 - : : 84 27 Si 5.5 +11 “ a é 84 38 52 5.667 —17 A d 84 48 Lee +12—18 s - 85 6 6.333 —19 - - - 85 22 65 6465 +18 - 85 30 6% 6.667 —20 : : 85 36 _ of Elliptic Polarization. 251 —7 7 +14 - ~ 4 85 49 WHET +15 - - : 86 7 —8 8 +16 - - ; 86 2] B85 417 ‘ ‘ 4 86 35 —9 9 ,+18 - ; ‘ 86 46 9195 +19 : a B 86 56 —10 10 +20 . M s 87 5 —lijll- - : : 87 20 —12 12 - iene : 87 35 —13 13 : 3 87 46 14 14 : tig : 87 56 —15 15 - ° 88 4 —16 16 . : : 88 11 reat Pe . : 88 18 —I8 18 : . : 88 24 —19 19 : : 88 28 —20 20 - . . 88 33 _ The first column of the preceding Tables shows the smal- lest number of reflexions at which a pencil of elliptically pola- rized light is restored to a single plane of polarization at the angle contained in the last column; and consequently the half of these numbers is the number of reflexions at which light is elliptically polarized at the same angle. Thus at three reflexions the ray is restored to a single plane of polarization at 63° 43’, and 79° 40’, and consequently at 14 reflexion it is elliptically polarized at that angle. This is easily understood when the number of reflexions is an integer; but it requires some explanation when the number is partly fractional. It has been already stated, in page 151, that elliptical polariza- tion may be completed at any fractional part of a reflexion; and since it begins to be restored the instant the polarization is complete, and again begins to be elliptically polarized after every restoration, the points of restoration may take place in the middle of a reflexion ; and though we cannot possibly ex- amine what takes place at these points, yet the effect must ap- pear when the fractional number of reflexions in the first co- lumn has been repeated so many times as to become a whole number. Thus a ray elliptically polarized by 1} reflexion 252 Dr Brewster on the Phenoména and Laws will be restored to a single plane at 22 reflexions at the same angle. It will also be restored at 22 x 2= 31, and at 22 x. 3 = 8, in which case its restoration will be seen at the eighth reflexion at the same angle ; and also at the sixteenth and twenty-fourth, &c. In this case the phase P will be ir = 672°, R = 33° 45’, and g = 11° 15/, from which we deduce the angles of incidence to be 63° 43’, and 79° 40’. In order to ascertain the existence of these points of restoration, I made the experiment at five and seven reflexions as multiples of 25 and 21, and I found the angles to be for five reflexions 68°, and for seven reflexions 20°, i in place of 6” 54’, and 69° 29’, as computed from the formula. The numbers in the third column, with the signs + and —, are the integer multiples of those in the first column, and show the number of reflexions at which the elliptically pola- rized light is restored, the numbers being carried the length of twenty reflexions. The sign + shows that the plane of the restored ray is to the right, and the sign — that it is to the left of the plane of reflexion. In order to determine the sign of the restored ray, we must consider that in the same quad- rant the signs necessarily alternate. Now at 73°, the maximum polarizing angle, the signs are —2, + 4, —6, +8, —10, +12, &c.; and I have also found that all the integer numbers in column Ist, Table I. have their signs + or positive, as +3, +5, +7, +9, &c., and all the even numbers their signs — or negative, as —4, —6, —8, —10, &c. ; whereas in Table IT. all the integer numbers are negative whether odd or even, thus, —3, —4, —5, —6, &c. By setting out, therefore, from these points, and attending to the alternation of the signs, it easy to determine for any number of reflexions its proper signs, whether it is a multiple of an integer or of a mixed number. In order to illustrate this Table, I have projected, in Fig. 3, Plate II. some of its results as far as six reflexions. The concen- tric arches IT, II II, &c. represent the quadrant of incidence for one, two, &c. reflexions, B being the point of 90°, and C that of 0° of incidence. 'The’point D or the line A D is the point or line of maximum polarization, viz. 73° for silver; and the figures 1, 2, 3, 4, 5, &c. show the points or nodes, and their of Elliptic Polarization. 253 distances from C, the angles of restoration. The loops or double curves lyi ng between the points 1, 2, 3, are drawn to give an idea of the i intensity of the elliptic polarization, which has its um at. 1, 2,3, &c. and its maximum at intermediate "These points of maximum intensity do not bisect the or are not equidistant from the ‘minima 1, 2; &c.; but such i is their relation to them, that the maximum for 7 reflex- ions is the minimum for 2 n reflexions corresponding to the same angle. Thus the maximum for one reflexion, viz. 73°, is the minimum for two reflexions; and the maxima for two reflexions, viz. 82° 30’ and 63° 43’, are the minima for four reflexions. The maximum may be found directly by comput- ing the angle of incidence, which corresponds to a phase in- termediate between the two minima, within which the maxi- mum lies. Having thus determined the various points of the quadrant, at which elliptic polarization is produced, and at which it is destroyed, after any number of reflexions ; and also the posi- tion of the plane of the restored ray, I shall proceed to inves- tigate the cause of those brilliant complementary colours which accompany these phenomena. As all transparent bodies have different values of their maxi- mum polarizing angle, appropriate to the index of refraction for each colour of the spectrum, it is reasonable to suppose, that, as elliptic polarization is effected at the maximum pola- rizing angle, this angle would vary for the differently colour- ed rays. That this is the case may be easily proved by ob- serving the angles of restoration for homogeneous light after two reflexions. In silver the difference of the angles for red and blue light is about 5° in the sun’s rays; so that calling 73° the maximum polarizing angle for the mean yellow ray, the angle will be 704° for blue, and 75$° for red light. Hence if we examine a pencil of white light twice reflected at 70°, and place the principal section of the analyzing prism in the plane —39° 48’, the blue rays will disappear and the red will remain visible. In like manner, at an angle of '75° 30/ the red will disappear and the complementary blue will be visible ; while at an angle of '73° the yellow will disappear, and red and blue will be seen together, one on each side of the NEW SERIES, VOL. Iv. NO 11, APRIL 1831. R “~ 254 Dr Brewster on the Phenomena and Laws place where the yellow has vanished. ‘At angles of incidence greater than 754° and less than '701, and also at intermediate angles, the blue or the red- will still predominate in the pencil, the blue being in excess at all angles greater than 73°, and the red in excess at all angles less than 73°. Such are precisely the phenomena which take place, as will appear from the following Table. . Angle of incidence of the two Re- flexions. Colours with ordinary Light. 63 Very pale yellow, growing whiter at less incidences. 64 Pale yellow. 65 Pale saffron yellow. 66 = Saffron yellow. 67 _Paler orange yellow. 68 Orange yellow. 69 Reddish orange. 70 = Tile red. 70i Vermilion red 71 ~~ Scarlet. 72 ~~ Bright pink. 78 Dark pink. 74 Deep China blue. 75 Indigo. 751 , Pure bright blue. 76 ~——«~Paler blue. 77 Whitish blue. 78 Blueish white, growing white at greater angles. It is obvious from what has been already stated, that with homogeneous yellow light the pencil will not vanish in passing from 73°, where it is evanescent, to 90°, and 0°, where it is also evanescent; but the intensity of the extraordinary pencil of the analyzing rhomb will increase from 0° to half the reflect- ed light, from 73° to 823°, and from 73° to 57° 16/, and will de- crease from the same points to 90° and 0°. The same is true of the red and blue rays, the former having its maximum in- tensity at an angle greater. than 823° and greater. than 57° 16, and the latter at an angle less shan: 821° and less than 57° 16’. In order to ascertain the phenomena in homogeneous light, « of Elliptic Polarization. 255 let us ; suppose that polarized yellow light suffers four reflexions from silver, and let us consider shat should take place in the loop 2, 3 of the quadrant IV, IV. (See Fig. 3.) At the node 2, or 73°, the inclination of the restored pencil is + 31° 52’, and at the node 3, or 82° 30’, it is—37° 22’, and the point of maximum between 2 and 3 is at 78°8’. If at 73° we place the principal section of the analyzing prism in the plane +-31° 52 the extraordinary ray will vanish, and the light will pass into the ordinary image ; and if at 82° 30’ we place it in — 37° 22’, the same effect will be produced. At 74° a small portion of light will pass into the extraordinary image, and this portion will gradually increase to 78° 8’, the principal section of the prism having been turned round gradually from +31° 52’ to _ 0°, as described in page 140. The ordinary and extraordinary images now approach most to equality, and they vary in inten- sity according to the same law in passing from 78° 8’ to 82° 30’, the axis of the prism having now come into the plane— 37° 22. The very same phenomena take place with red and ‘blue light, only the points of restoration and the maximum occur at different angles of incidence, so that the spaces be- tween the minima have different lengths for the differently coloured rays. These spaces or loops, therefore, will over- lap each other, as will be understood from Fig. 4, where they are shown separately, r 7’ being the red loop, y y’ the yellow, v v’ the violet one, the points 7, y, v, 7’, y’, o' the minima or nodes, and a, b, c, the maxima. When these loops are viewed superposed as when they form white light, then the tint in the extraordinary image will be white, minus the three ‘quantities of light that have disappeared from the extraordi- nary ray. At the line m n, passing through the node of the red loop, the red will have vanished, and the mixture of the yellow and the violet which remains will constitute a greenish blue pencil, decreasing in its blue tint towards a, and becom- ing pink, and then red towards ¢ s, in consequence of part of the light of the other red loop above 7 now passing into the extraordinary ray. Atv and at v’, where the violet disappears, the mixture of the yellow and the red will form an orange pencil, which will be reddest at v and v’, and shading off to white ata. At the line s ¢ the yellow vanishes, and across , 256 Dr Brewster on the Phenomena and Laws the upper part of the Juminous disc, there will be light with an excess of red, and across the lower part of it, light with an excess of blue. ° This takes place with even numbers of reflex-’. ions; with odd numbers the blue light is uppermost and the red undermost. The phenomena of colour, as seen by white light, vary greatly with the number of reflexions, both with respect to the depth of the colours themselves and the rapidity of their changes. In order to investigate the nature of these varia- tions, let us consider what will take place at 2, 4, 6, 8, and 10 reflexions from silver in the loops above and adjacent to ‘73° the maximum polarizing angle. The following are the num- bers which regulate the phenomena. No. of mF Fig. 6. the Re- Nature of the Reflexions. Limits of the - Length of er pty = flexions. Baope. the Loops. Plane, org, ab’ 2 First of the series 73°— 90° 0’ §=:17°. 0 39°48’ cd 4 First of the series 73 — 82 30 9 30 37 22 ef 6 Multiple of 3 73.— 79 40 6 40 32 25 gh .8 Multiple of 22 73—78 8 6. 8 27, 53 mn 10 Multiple of 23 73— 77 13 4 13 24 16 This Table may be illustrated by Fig. 5, where A B passes through the incidence of 90°, and C D through that of 73°, the points m, g, e, c, @ corresponding respec- tively with the incidences of 77° 13’, 78° 8’, 79° 40’, and 82° 30’, or those at which the ray is restored by 10, 8, 6, and 4 reflexions. The curvilineal spaces a 6, c d, e f, g h, and mm, are the loops already referred to, whose breadths repre- sent the intensity of the extraordinary ray, which is a minimum at the nodes a, c, e, g, m, and b, d, f, h, m, and reaches its maximum near the middle of the loops. . If the image reflected from the silver is a circular dise of white light of a given magnitude, then by two reflexions at 73°, or at the point 0 the extraordinary image will be red above and blue below, when the principal section of the ana- lyzing prism is in the plane — 39° 48’ ; but these colours will be very faint, as the dise occupies but a small part of the loop ab. 'The disc indeed may be made so small, that the extra- ordinary image will. entirely disappear in this loop. In this case the ordinary image will be white, as all the reflected light of Elliptic Polarization. 257 will pass into it. At four reflexions the loop c d is little more than one-half of a 6, and consequently the light will vary much more rapidly from d to the maximum. When the analyzing _ prism has its principal section'in the plane — 37° 22’, the ex- traordinary image at c will be coloured with red light above and blue below ; and when it is in the plane + 31°52’, the ex- traordinary image at d will be similarly coloured: The colours will be much brighter than in the case of two reflexions, and consequently the extraordinary image will not vanish. The consequence of this is, that the ordinary image is not white as before, but yellow, because a considerable portion of red and blue light are left in the extraordinary image. As the number of reflexions increase, and the loops ef; gh, - &e. diminish, the disc will occupy a greater proportion of the whole loop, and the red and blue colours with which it is crossed grow brighter and brighter, and come closer and closer to their line of junction in the middle of the dise. Hence a greater quantity of red and blue light is left out of the ordinary image, which on this account becomes yellower and yellower, and at last of a greenish hue. In order to determine the position of the principal section - of the analyzing prism, when the extraordinary image is a mi- nimum for any angle of incidence «, and any number of re- flexions, let «|, + = the inclinations of the plane of polarization of the restored ray at the nodes a, 6; m, n = the inclinations cos (i + 7’) ‘cos (i— i’) the angles of incidence at the nodes; 2 — the inclination 9 suited to the incidence «. _ Now it is obvious that at the one node, the position of the principal section of the analyzing prism, when the extraordi- nary image is a minimum, is + 1, and that it gradually changes to 0° and then passes to — x, thus undergoing a change equal _ to - + x while the inclination ¢ varies by a quantity equal to m—mn. Hence calling I the inclination of the principal sec- tion to the plane + \) at the angle of incidence «, we have m—n:V+x=m—ae:f. or values of 9 in the formula tan 9 = suited to / | 258 Dr Brewster on the Phenomena and Laws : _ ae - Se Henee I= 4 +x (7) : the When a#=n, T=V+x weet When z = ——, ea *=23 andI= vex, . When the nodes of the loop are on different sides of the maximum polarizing angle, which happens only in the middle loop of 3, 5, '7, &c. reflexions, then m and n have opposite signs, and consequently their difference is m + n, and, as in this ease — n, the formula becomes I — ps (==). It is impossible to determine the relative intensities of the ordinary and extraordinary image at any angle a, because this must depend on the relative intensities of the pencil by whose interference the elliptical polarization is produced. In silver these pencils approach to equality, but in steel and other me- tals they are very. unequal. iil oh} Having thus shown how to determine the phenomena of el- liptic polarization for any angle of incidence, for any number of reflexions, and for homogeneous light of any colour, I shall conclude this paper with some observations on a very remark- able anomaly which has presented itself in the course of this inquiry. The phenomena which have been described, indicate very clearly that the angle of maximum elliptic polarization for one reflexion, or the angle of restoration after two equiangular re- flexions, is the maximum polarizing angle of the metal, and consequently that its tangent is the index of refraction, as shown in the following Table.* i elk Gs 3 * This Table completely proves that the refractive index of metals can- not be deduced from their reflective power; for silver, which surpasses them all in reflective power, stands very low in refractive power. Mr Herschel has noticed the difference between the indices of refraction de- duced by these two methods in the case of mercury, which he makes 5.829 as given by its reftective power, and 4.16 as given by its polarizing angle. He makes the index for steel 2.85. When we consider that metals reflect the light that enters their substance, it must be obvious that the quantity of light which they reflect is a function not only of their refractive power, but of their transparency, which will be proportional to the intensity of the reflected pencil that has entered the metal. If this is the case, the tran- sparency will be proportional to the inclination of the plane of the restored of Elliptic Polarization. 259 Names of Metals. Angles of Maximum Index of Re- polarization. fraction. Graintin—- - 78 30 4.915 Mercury - - 78 27 4.893 Galena - - 78 10 4.773 ' Tron pyrites - 77 300 4.511 Grey cobalt “ 76 56 4.309 Speculum metal % 76 0 4.011 Antimony melted - 75 25 3.844 Steel Ags - 75 0 3.732 Bismuth . cs 74 50 _ 8.689 Pure silver - soo Se: @ 3.271 Zinc - - 72 30 3.172 Tin plate hammered 70 50 2.879 Jewellers’ gold - 7O 45 2.854 _ This conclusion is not opposed by any of the phenomena, when we consider merely the mean refrangible ray to which these numbers refer: but when we use homogeneous light, a very strange anomaly occurs.. The maximum angle of elliptic polarization for red light in the case of silver is 75° 30, and for blue light 70° 30’, giving Angle. - Index of refraction for red light, . 3.866 15 30 ; mean ray, 3.271 73 0 blue light, - 2.824 70 30 ' the order of the refrangibilities being inverted. The perfect similarity between the action of metals, and the total reflexion of the second surfaces of transparent bodies, promised to throw light upon this difficulty. I accordingly examined the formula of Fresnel for total reflexion, where the phase P is thus expressed : bey pes 2 m? (sin i) *— (m? + 1) (siné)? +1 ee m* +. i (sinz)*— 1 : From this formula it follows that when m = 1.51, and i= 54° 37’, P will be 45° for one reflexion, and consequently for ray after two reflexions at the maximum polarizing angle, and the order of the transparencies of the different metals will be that of the Table, p. 144. See Mr Herschel’s Treatise on Light, $ 594, 845. 260 Dr Brewster'on the Phenomena and Laws, &¢. two reflexions 2 P — 90°. If m increases as it does for blue light, then the phase will be 45° at an angle of incidence above 54° 37’, that is, the circular polarization of the pencil will take place at a greater angle of incidence for blue than for red light, which is the reverse of what takes place in metals. Upon making the experiment, however, with total reflexion, we shall find that the blue rays are circularly polarized by two re- flexions at a less angle than the red rays, thus approximating the two classes of phenomena even with respect to this singu- lar anomaly. Hence in order to accommodate M. Fresnel’s for- mula to homogeneous light of different colours, let m be the index of refraction for the homogeneous ray, and d the differ- ence between it and the mean index, then the formula for the phase P will become Cos P = 2M ED? (sin i) *— ((m +d)? +1) (sini)? 41 ne ((m =e d)* +1) (sine)? 41 the sign + being used for the red or least refrangible rays, and — for the blue or most refrangible. For the same reason, in calculating the phases of an ellipti- cally polarized homogeneous ray by means of the formula tan __ cos (2 +7’) ~ cos (i—?’) = eae the sign + being used for the red or. least refran- gible, and — for the blue or most refrangible rays. As the theoretical considerations upon which M. Fresnel is said * to have constructed his formula, did not present to him © the above anomaly, it would be in vain for me to seek an ex- planation of it. I may just mention, however, that at the second ‘surfaces of bodies the angle of maximum polarization, » we must determine 7’ from the formula sin 7 cs j 2 . or tan — is necessarily less for the least refrangible than for the mean rays, which is the reverse of what takes place at the first surface; and since the limit:of total reflexion whose sine is —-, or since the sphere or circular polarization commences * Tam acquainted with M. Fresnel’s formula only from the account , given of it by Mr Herschel. Account of four Cases of Spectral Illusion. 261 sooner for the least than for the most refrangible rays, it might be expected that the angle of maximum circular polarization should be less for these rays, as I have found to be the case. Although we do not understand the nature of the forces by which metals reflect the two oppositely polarized pencils, yet they act exactly like the second surfaces of transparent bodies when producing total reflexion. Setting out from a perpendi- cular incidence, the least refrangible rays begin to suffer the double reflection sooner than the mean ray, and they sooner reach their maximum of elliptic polarization, thus exhibiting the inversion as it were of the spectrum, which we have noticed. The theory of elliptic vibrations as given by Fresnel, will no doubt embrace the phenomena of elliptic polarization; and when the nature of metallic action shall be more thoroughly examined, we may expect to be able to trace the phenomenon under consideration to its true cause. Auterty, February 19th, 1830. Art. 1V.—Account of other Four Cases of Spectral Illusion. (Continued from No. vi. p. 245.) I continve my communications to you of the singular spec- tral illusions to which Mrs has been unhappily liable. The last of which I give you an account took place, I think, on the 14th March last. From that time to the 5th October, no phenomenon of the kind was experienced, and we began to hope that these symptoms of internal malady, with their cause, ‘had disappeared. On that day, however, between one and two o'clock in the morning, I was awoke by Mrs who told me that she had just seen the figure of my deceased mother draw aside the bed-curtains, and appear between them. The dress and look of the apparition were precisely those in which my poor mother had last been seen by Mrs at Paris in 1824. A few days afterwards, on the 11th October, Mrs sitting in the drawing-room on one side of the fire-place, saw the figure of another deceased friend moving towards her 262 Account of four Cases of Spectral Illusion. from the window at the-further end of the room. It approach- ed the fire-place, and sat down in the chair opposite that in which Mrs was seated. As there were several per- sons in the room at the time, Mrs describes the idea uppermost in her mind to have been a fear lest they should be astonished or alarmed at her staring in the way she was conscious of doing, at vacancy, and should fancy her intellect disordered. Under the influence of this fear, and recollecting a story of a similar effort in Sir W. Scott’s work on Demo- nology, which she had lately read, she summoned the force and resolution necessary to enable her to cross the space before the fire-place, and seat herself in the chair which appeared oc- cupied by the figure. She did this; the apparition remaining perfectly distinct, till she sat down as if in its lap, when it was no longer perceived. On the 26th of the same month, about two o’clock pv. m. Mrs — was sitting on a chair by the window in the same room with myself. I heard her exclaim, ‘*‘ What have I seen ?” and on looking towards her perceived a strange expression in her eyes and countenance. On inquiry, she told me that a carriage and four had appeared to her to be driving up the entrance road to the house. As it approached, she felt in- clined to go up stairs to prepare to receive company, but found herself unable to move or speak, as if spell-bound. The carriage came nearer, and as it arrived within a few yards of the window, she saw the figures of the postillions and the per- sons inside take the ghastly appearance of skeletons, and other hideous figures. ‘The whole then vanished entirely, and she made the exclamation which I heard. October 30th.—Mrs tells me that this morning, while sitting in her own room with a favourite dog in her lap, she distinctly saw the same dog to all appearance moving about the room, during the'space of about a minute or rather more. December 3d.—About nine o'clock at night, sitting near Mrs in the drawing room, both, as I thought, occu- pied in reading, I felt a pressure on my foot as if intended to attract my attention. On looking up I observed Mrs s eyes fixed with a strong and unnatural stare on a chair about nine or ten feet distant. I perceived immediately she was un- ‘Mr R. W. Fox on the Mines of Cornwail. 263 der the influence of a spectral illusion, and asked her what she saw. The expression of her countenance then changed, and, on recovering herself, she told me she had seen my brother, who was alive and well at the moment in London, seated in the opposite | chair, but dressed.in grave clothes, and with a ghastly countenance, as if scarcely alive. _ This is the last apparition which has yet occurred. ‘The first remark that suggests itself on these successive delusions is the extraordinary resemblance of the greater number of them to the usual circumstances of the ghost stories we have all heard repeated, with more or less of authority for them, from our cradles upwards. Here, however, the apparition of the dovible of the lap-dog, like the previous one of the cat, in- troduces itself most happily as a key to the mystery, and a guarantee to the imagination of the most credulous and bigot- ted believer in the world of spirits, of their strictly natural and physical causes, of their being in fact, beyond question, mere optical illusions induced by disease. - T may here also repeat what I likewise observed Lefties of the previous apparitions, Mrs confidence that in no one of these instances were her thoughts dwelling on, or tend- ing in any way towards, subjects which could be supposed as- sociated with the idea of the persons who appeared to her. Consequently the imagination, memory, and other faculties of the mind seem to be wholly unconcerned in the agents or hereete of the spectral forms. ) -I shall continue to keep a journal of any similar facts ; isa shall be glad if Dr Hibbert or yourself can suggest any ex- periments to be adopted 1 in case they should continue to manifest themselves, with a view to ascertain their immediate causes. Art. V.—On the Electro-magnetic properties of metalliferous Veins in the Mines of Cornwall. By Ropert Were Fox, _ Esq. of Falmouth, Hon. Mem. Plymouth Institution, and M. R. Geological Society of Cornwall. Communicated by . the President. * Iw one of my communications to the Cornwall Geological Society on the high temperature of the interior of the earth, * Abridged from the Phil. Trans, 1830, p- 399. 264 Mr R. W. Foxon the Electro-magnetic properties I ventured to express a belief that mineral veins, and the in- ternal heat, are connected with electrical action. ‘This opinion, founded as it was on the curious arrangement of the veins, &e. in primitive rocks, I have had the satisfaction to find confirmed by experiments made in some of the mines of Cornwall; and I doubt not that the existence of electricity in metalliferous veins similarly circumstanced, and capable of conducting it, will prove to be as universal a fact, as the progressive increase of temperature under the earth’s surface is now admitted to be, much as my conclusions on this point were at one time controverted. In my first experiment, I did not succeed in Reieibia any electricity ; butin my second I had the gratification to observe considerable electrical action. My apparatus consisted of small plates of sheet copper, which were fixed in contact with ore in the veins by copper nails, or pressed closely against it by wooden props, stretched across the ‘ levels” or galleries. Between two of these plates at different stations, and a galvanometer, a communication was made by means of copper wire one-twentieth of an inch in dia- meter which was at first coated with sealing-wax ; but after- wards this precaution was dispensed with. ‘This galvanometer consisted of a magnetic needle three inches and a quarter long, one-eighth of an inch wide, and one-twenty-eighth thick. It was inclosed in a box four inches square, and one inch in depth, having a plated copper wire one-fiftieth of an inch in diameter coiled round it twenty-five times. No magnet was used to neutralize the terrestrial polarity. The intensity of the electro-magnetic action differed greatly in different places :—in some cases the deviation of the needle was inconsiderable, in others it went completely round the cir- cle. In general it was greater, ceteris paribus, in proportion to the greater abundance of copper ore in the veins, and in some degree perhaps to the depth of the stations ;—and where there was little or no ore, there was little or no action. Hence it seems likely, that electro-magnetism may become useful to the practical miner in determining with some degree of proba- bility at least, the relative quantity of ore in veins, and the di- rections in which it most abounds. of metalliferous Veins in the Mines of Cornwall. 265 When the distance of the plates from each other in a hori- zontal direction was only a few fathoms, and the copper ore, between them was plentiful, and uninterrupted by non-con- ducting substances, or the workings in the mine, no action oc- curred, owing no doubt to the good conducting power of the vein ; but where a cross vein of quartz or clay happened to be between the plates under similar circumstances, the action was usually great. When the communication was established between two plates at different depths on the same vein, or between different veins, whether at the same level or otherwise, the electrical action was in general the most decisive. In fact, veins which in some instances were almost destitute of ore, and did not affect the needle per se, did so, though perhaps only in a slight de- gree, when electrical communications were made between them. It will be seen that the direction of the positive electricity was in some cases from east to west, and in others from west to east; and when parallel veins were compared, its general tendency was, I think, from north to south, though in several instances it was the reverse. In veins having an underlie to- wards the north, the east was commonly positive with respect to the west; but in veins dipping towards the south, the con- trary was observed, with one exception only, and that under ra- ther unusual similar circumstances. In comparing the relative states of veins at different depths, the lower stations appeared to be negative to the upper ; but exceptions sometimes occurred when a cross vein of quartz or clay intervened between the plates, and the higher one was on the negative side with re- spect to the horizontal currents. In such cases it may be supposed that there is an accumu- lation of electricity in different states, on the opposite sides of the non-conducting vein. Such intersections of ore veins, and their being often very rich to a great depth in one direction and not in another, added to their varying underlie at different depths, which is not unfrequently reversed, may tend to pro- duce apparent anomalies in experiments of this nature. At Huel Jewel mine, I obtained results between a heap of copper ore at the surface, and a plate fixed at different depths against the ore in the vein; the latter becoming more negative, } 266 Mr R. W. Fox on the Electro-magnetic properties fs in proportion to the depth at which it was placed. Piles of copper ore at the surface did not act on the needle when tried together, independently of veins, nor was it to be anticipated that they would. ry It is not improbable that the progressive increase of negative electricity observed in descending into our mines, if hereafter . confirmed, may be found to be connected with the progressive increase of temperature. I have not, however, discovered an distinct connection between them at the same level, but then the differences of temperature are comparatively small. Nor does the electricity appear to be influenced by the presence of the workmen and candles, or by the explosion of gunpowder, although some veins of copper ore were blasted on different occasions in the immediate vicinity of the copper plates. And at a very productive copper vein in Great St George Mine, the ground is so soft that gunpowder is not used; yet the needle was powerfully acted upon by the electricity it contain- — ed. On this occasion, as well as on some others, I remained with the galvanometer at the surface, letting the wires down through the shafts ; and in this manner I have sometimes found the electricity act with considerable energy, so as even to cause the needle to revolve with some velocity. In connection with the electricity of veins, I deemed it de« sirable to ascertain the relative power of conducting galvanic electricity possessed by many of the metalliferous minerals; and it appeared to be in about the following order, viz. Conductors. Copper nickel, Purple copper, | Yel sulphuret of ditto, Vitreous ditto, Sulphuret of iron, Arsenical pyrites, Sulphuret of lead, Arsenical cobalt, Crystallized black oxide of manganese, Tennantite, Fahlerz, of metalliferous Veins in the Mines of Cornwall. 267 Very imperfect conductors. Sulphuret of molybdenum, . Sulphuret of tin, or rather bell-metal ore. - Non-conductors. Sulphuret of silver, Ditto of mercury, Ditto of antimony, Ditto of bismuth, Cupriferous ditto, Realgar, Sulphuret of manganese, Ditto of zinc, Mineral combinations of metals with oxygen, and with acids. All the conductors of galvanic electricity were so likewise of common electricity ; to which: may be added the oxide of tin, and, in a less degree, the sulphurets of bismuth and silver, the phosphate of manganese, and a few of the oxides. Sul- phuret of zinc appeared to be a more perfect non-condactor of common electricity as well as the sulphuret of antimony, than the red oxides of those metals. _ Amongst the rocks prevalent in Cornwall, clay-slate or “killas” seemed to possess the property of conducting common electri- city in a slight degree, but only in the direction of its cleavage, perhaps owing to the moisture it retained. I mention these facts in some detail, because it is curious to observe that the conducting power of metalli¢ ores appears to have no reference to any of the electrical or other properties of the metals in a pure state, or to the proportion of them in combination, Silver and mercury, for example, are combined with, comparatively, very small quantities of sulphur ;—and zinc, Which seems to hold an opposite place to silver in the electrical scale, is also found in combination with a much less proportion of sulphur than is contained in copper pyrites, ‘though the latter is one of the best mineral conductors of elec- tricity. ' ~» There are many other analogous examples, which prove that no conclusion can be drawn, @ priori, from the nature or 268 Mr R. W. Fox on the Electro-magnetic properties — chemical arrangements of minerals, as to their relative electri- cal properties. Much time and attention have been bestowed by geologists on the consideration of the origin and comparative ages of veins, and but little, I apprehend, on the purposes for which they are designed. It appears to me that it will prove a vain attempt to recon- cile a multitude of facts observable in our mines with any known natural causes. I may refer to a few of them:— - 1st, The very oblique descent of a large proportion of the veins into the earth, in some cases in very hard rock, and in others in ground so soft that it would immediately fall in, however small the excavation, without being completely sup- ported by timber. Were it possible to conceive fissures to exist under such circumstances, it is not reasonable to suppose that they would not take the direction in which the resistance would be least, that is, either the vertical, or the line of- the cleavage of the rocks. 2d, Veins are often divided into branches, which unite again at a considerable depth, including between them vast portions of rock perfectly insulated by the ore or vein-stones from the general mass: these, it is evident, could not have existed as fissures for a moment. 3d, Veins are continually subject to changes in their hori- zontal direction and underlie; their size also often varies exceed- ingly, one part being many times wider than another, without any reference to their relative position or depth under the surface. 4th. Although a portion of their vein-stones are usually quite distinct in their characters from the rocks they traverse, they are generally, in part, of the same nature, and vary with’ the containing rocks, whether granite, elvan, killas, &c.; and they are commonly too regularly arranged in the veins, and are found inclosing insulated portions of the ore, &c. in their very substance, to admit of the idea of their having been origi- nally mere broken fragments of the inclosing rocks. At Dolcoath Mine there is an instance of one ore vein inter- 3 of metalliferous Veins in the Mines of Cornwall. 269 : secting another at different depths, and being itself intersected and even shifted by the same vein at a greater depth. my other facts might, if it were necessary, be accumulat- ed, relative to the position and intersection of veins, as well as the nature and arrangement of their contents, which, with those I have stated, are calculated to throw entire discredit on the various hypotheses which have been invented to account for their origin. But my object is, rather to suggest whether the arrangement of veins, &c. does not argue design, and a pro- bable connection with other phenomena of our globe. Metalliferous veins, and those of quartz, &c. appear to be channels for the circulation of the subterraneous water and vapour ; and the innumerable clay veins or “ flucan courses” (as they are termed in Cornwall,) which intersect them, and are often found contained in them, being generally impervious to water, prevent their draining the surface of the higher grounds as they otherwise would, and also facilitate the work- ing of mines to a much greater depth than would be practi- cable without them. With respect to their electrical properties, it may be observ- ed, that ores which conduct electricity have generally, in this country at least, non-conducting substances interposed in the veins between the ore and the surface. Thus a brown iron ochre with quartz, &c. named ‘ gossan” by the miners, is al- most invariably found resting on copper. Sulphuret of zinc -occurs sometimes in the same situation, both with regard to copper and lead; but tin ore, which is a non-conductor, is without either, and is mostly found nearer the surface than copper. Tin veins are usually intersected by those of copper when they do not coincide in their horizontal direction or underlie ; -thus, in this case, the conducting veins traverse the non-con- ducting ones. And when two veins of copper meet at oppo- site angles in descending, they are, I apprehend, generally found to be unproductive at and near the place of junction ; but when they unite, proceeding downward in the same direc- tion but at different angles, they are commonly observed to be enriched. ‘These facts appear curious when regarded ‘in con- nection with the opposite currents of electricity in veins hav- ‘Ing opposite dips. NEW SERIES, VOL iV. NO. Il. APRIL 1831. s 270 Mr R. W. Fox on the Electro-magnetic properties There are some districts in this county in which the ore veins have generally a north underlie, and in others the south prevails ; and it often happens that when lodes occur which deviate from the prevalent underlie of the others, in any dis- trict, the former are intersected, and sometimes shifted by the latter. This is strikingly the case in numerous mines in the parishes of St Agnes and Perran. ‘The usual horizontal bearing of the copper and tin veins in our principal mining districts, appears to be nearly E. and — W., or rather from E.N.E. to W.S.W. but in others they deviate materially from these directions, sometimes to E.S.E. and W.N.W.: indeed, in some places this is s the prevailing course of the veins of ore. When veins containing the sulphuret of silver occur, (which as I have before stated is a non-conductor of electricity,) they are generally found nearly at right angles to the copper and tin veins, and seem thus to assume in great measure the cha- racter of cross veins of quartz, clay, &c. With respect to the two latter, it has been observed that when they shift the ore veins, there is frequently to be found in them scattered stones of ore, or a small vein of it, or ** leader” (to use a mining term,) between the dislocated parts of the lode. This is also the case often with slides; so that, although the -horizontal transfer of the electricity may be much impeded, it does not seem to be wholly intercepted. The quartz contained in cross veins is usually of a fibrous or radiat- ed texture, and differs materially from that found in the east and west veins. aN All our mining districts abound more or ‘Jéss with veins or dykes of a rock generally possessing a posphyriae character, termed by the miners “Elvan courses.” Their width is ex-_ ‘tremely various, sometimes as much as fifty fathoms and up- wards. Their direction in general is nearly N.E. or E.N.E. to S.W. or W.S.W., and their underlie is with few exceptions towards the N.W., and at various angles from the perpendi- cular, often exceeding 45°. They are penetrated by ore-veins in almost every direction, from their greater underlie, and usually more considerable deviation from an east and west bearing than the latter. It has been observed that copper and tin lodes generally become changed in quality whilst in the of Metalliferous Veins in the Mines of Cornwall. 271 elvan ; and indeed this remark applies to any change of rock : thus a vein productive in granite commonly becomes barren in killas, and vice versd. - Many of the phenomena above referred to bear striking analogies to common galvanic combinations, and the discovery of electricity in veins seems to complete the resemblance. ‘T have been informed by intelligent persons who have visit- ed some of the mining districts of Mexico, Guatimala, and Chili, that there is a general resemblance between the veins, elvan courses, &c. in some parts of those countries and our own; and I think it has been noticed by Baron Humboldt, that the stratification of primitive rocks in different, and far distant parts of the world, has a general tendency from the N.E. towards the S.W. -. Such analogies become highly interesting when regarded in connection with terrestrial electricity, magnetism, and heat ; for if it be granted that the two latter increase in intensity at great depths in the earth, they are evidently so connected with electrical action that the augmentation of it also, in the inte- rior of the globe, may be reasonably inferred. However this may be, assuming that metalliferous veins exist more or less in primitive rocks generally, (and experience favours this assumption, whether we refer to the new mines which have been discovered in various parts of North and South America, Siberia, Ireland, &c. or to the mining county of Cornwall, in which whole districts have comparatively of late been found abounding with mineral treasure, where none had been formerly suspected to exist,) it may I think be presum- ed, that the electrical currents, which so affect the needle in the galvanometer, may likewise influence the direction of the magnetic needle on the surface of the earth : at least no expla- nation of this phenomenon appears to be so plausible, or so well connected with ascertained facts. Even the cause of the variations of the needle, mysterious as it has hitherto appear- ed to be, may probably be referred to the relative energies of the opposing electrical currents, which are perhaps subject to occasional modifications ; and the appearance of earthquakes and volcanic action, from time to time, seems to countenance the probability of such changes. 272 Mr R. W. Fox on the Mines of Cornwall. _ Nor should it be overlooked in reference to this view of the subject, that the oblique bearing which is generally observable in the strata and veins, with respect to the equator, causes them, as it were, to cross at opposite sides of the globe in the same parallels of latitude, so that their tendency, if any, must necessarily be to produce more than one magnetic pole in each hemisphere. Thus, in this respect also, the hypothesis accords with the interesting fact lately announced ;—of Professor Hansteen having ascertained the existence of a second magne- tic pole within the arctic circle. The revolution of the earth on its axis from west to east seems moreover to harmonize with the idea of oblique electrical currents ; since rotation in the same direction may be produced by corresponding electro- magnetic arrangements. Before I conclude, I will briefly mention a few facts rela- tive to the temperature of some of the mines in Cornwall. At Tingtang copper mine, in the parish of Gwennap, at the bottom of the engine shaft, which is in killas, and 178 fathoms deep, the water about two months ago was at the tem- perature of 82°. In 1820, when the same shaft was 105 fathoms deep, the temperature of the water was 68°: thus an increase of 14° has been observed in sinking 73 fathoms, which is equal to 1° in 5 fathoms. At Huel Vor tin mine, near Helston, the water was 69° at the bottom of a shaft 139 fathoms deep, in the year 1819. It is now 209 fathoms deep, and the temperature is 79°, which gives a mean increase of 1° in sinking 7 fathoms. This part of the mine is in killas. . The bighest temperature of the water at the bottom of Pol- dice copper and tin mine in the parish of Gwennap, in 1820, which was then 144 fathoms under the surface, was 80°. It is now 176 fathoms deep, and the temperature is 99°; and in a cross level 20 fathoms, further north, the water is 100°. The two last-mentioned temperatures are the highest hither- to observed in any of the mines of this county ; and the in- crease is equal to 19° in one case, and 20° in another, in sink- ing 32 fathoms, or 1° for 1} fathom. Three persons only were employed at a time near each of these stations, and the water pumped up from this part of the mine was estimated at M. Matteucci on the Action of the Pile. 273 1,800,000 gallons in twenty-four hours; and I found on ex- amination that it contained a considerable quantity of common salt in solution. Arr. VI.—Observations on the Action of the Voltaic Pile. By _ M. Marrevcci.* Ina Letter to M. Arago. ‘Penmit me to communicate to you some critical observations on the chemical explanation of the developement of Voltaic elec- ' tricity, given by M. De La Rive. The experiments of M. Pfaff, published in your annals for J uly 1829, sufficiently satisfied me that we may develope elec- tricity by means of contact only, and without chemical action. In order to convince me still more of this, I made some ex- periments on this species of electricity, by taking the frog for a galvanometer. With this view, I assured myself before-hand that there was no chemical action between water distilled and well purged of air, and zinc either alone or in contact with copper; and I was unable, indeed, even after several hours contact, to dis- cover, by the aid of the most sensible reagents, the presence of zinc or of the oxide of copper. After this it would be er- roneous, (in trying to show that chemical action is the cause of electricity by contact,) to conclude that there is chemical action because there is a developement of electricity. Being thus convinced that there is no chemical action between water distilled and purged of air, and zinc or copper, I began by suspending a prepared frog by a hook of zinc, which was fixed in the bottom of a receiver for gas, and soldered to a copper wire of greater length. In this manner, in order to prevent contractions, I had ane to touch the muscles of the thigh with the copper wire. In order to remove all suspicion of chemical action, I wash- ed the prepared frog in water distilled and purged of air, in order to carry off any animal fluid, I afterwards suspended it ‘by the nerves on the zinc hook, and I filled the receiver with distilled water, and afterwards with pure hydrogen gas. When the thigh was then touched with the copper wire, I observed * Ann. de Chimie, tome xly. p. 106. 274 Col. Aubert on the Spontaneous Inflammation the same contractions as if the experiment had been made in pure air.’ I tried these experiments in vacuo, in carbonic oxide, carbonic acid, and in oxygen either humid or dry, and £ al- ways observed the same contractions in the frog. Hence I am led to believe, that the contact alone of different metals may develope electricity. I also find an objection to the theory of M. De La Rive in the limited change which the electromotive force may develope and retain free. Chemical action, however, does not cease to exert a onuid influence on the developement of this force, as heat does on the phenomena of thermo-electricity. For, August 9th, 1830. Art. VII.—On the Spontaneous Inflammation of powdered Charcoal in great masses. By M. Avzerr, Colonel of Artillery. Spontaneous inflammations of charcoal have taken place in gunpowder manufactories under different circumstances, but most commonly when this substance, introduced in pieces, was crushed by the first strokes of the bruiser. Spontaneous i in- flammations of pulverized charcoal, however, took place in 1802 at the powder-work of Essone, in 1824 at that of Bouchet, in 1825 at that of Esquerdes, and in 1828 at that of Metz. Various experiments were made at Metz to ascertain the cir- cumstances under which these inflammations took place, and the following are the general results given by Colonel Aubert. Charcoal triturated in tons with bronze bruisers is brought to. a state of extreme division. It has then the appearance of an unctuous fluid, and occupies a space three times smaller than in rods of from fifteen to sixteen centimetres long. Tn this state of division it absorbs air much more readily than when it is in rods: The absorption is, however, still very slow, and requires several days to be completed. It is ac- companied with a disengagement of heat, which rises to 170° or 180° centigrade, and ought to be considered as the true cause of the spontaneous inflammation. of powdered Charcoal in great masses. 275 The inflammation begins about the centre of the mass, at twelve or fifteen centimetres below its surface, and the tempe- -rature is always higher at this place than at any other. There ought, therefore, to be established towards the borders of the mass a descending current of air which bends itself to- wards the centre, and becomes vertical without penetrating to the lower parts of the mass, where the temperature rises a very little. Itis from this cause that a portion only of the char- coal is concerned in the phenomenon. ‘The rest performs the part of an insulating body, and preserves the heat at the centre. Variations in the barometer, thermometer, and hygrometer, appear to have no sensible influence on the spontaneous in- flammation of the charcoal. If such an influence exists, the experiments have not been sufficiently multiplied to enable us to perceive it. Black charcoal, strongly distilled, heats pie inflames more readily than the orange, or that which is little distilled, or than the charcoal made in boilers. ; Black distilled charcoal, the most inflammable of the three, ought to have a mass of at least thirty kilogrammes, in order that spontaneous inflammation may take place. With the less inflammable varieties, the inflammation takes place only in larger masses. In general the inflammation is more certain and active in proportion to the shortness of the interval between the carbo- nization and trituration of the charcoal. Air is not only in- dispensable for spontaneous inflammation, but it must also have free access to the surface. The increase of weight which takes place in the charcoal is owing not only to the, fixation of the air, but also in | part to the absorption of water. During the trituration the air experiences no alteration from the charcoal, nor even at the moment of inflammation. Sulphur and saltpetre added to the charcoal deprive it of the property of inflaming spontaneously, yet there is still an absorp- tion of air and a generation of heat; and though the rise of temperature is not great, it would nevertheless be prudent not to leave these mixtures in too large masses after trituration.— Abstracted from the Ann. de Chimie, Tom. xlv. p. 73. 276 . Dr Hibbert’s History of the Ant. VIL.—History of the Brown Coal Formation of the Lower Rheinland. By S.Hrszert, M. D., F. Kk. S. E. &e. Com- -municated by the Author. 4 ‘No tertiary deposit in Europe is perhaps so difficult to explain in its various relations, as that which bears the name of the Brown Coal Formation. Asalmost every writer who has taken up his pen on the subject has differed from his predecessor in the views which he has adopted of its relative age, it will be easily imagined that I have imposed upon myself a task of no little intricacy. This is indeed my own persuasion, and I enter upon the investigation with a corresponding diffidence. I have said thus much as an apology for the rather novel mode in which I shall enter upon a description of the Brown Coal Formation of the Lower Rhine. It will be considered in connection with the general geology of the district, with the view that its earliest manifestation may be recorded. In con- formity, therefore, with this plan, I shall, as a preliminary measure, attempt, : Ist, A Sketch of the Geological History of the Lower Rhein- land previous to the developement of the Brown Coal For- mation. The brown coal deposit, which is the subject of the pre- sent dissertation, is found on both sides of the Rhine, from the neighbourhood of Coblentz to that of Cologne. The fundamen- tal rocks on which it is placed consist of argillaceous and grau- wackeschist, the latter containing insome places organicremains. Of secondary rocks there are no indications. If they ever did exist, we must attribute their disappearance to causes of degradation, which, there is no doubt, have removed many such deposits in various parts of the globe, to fill up distant — seas and lakes. 'The circumstance, however, of strata corre- sponding with the upper green sand of England, which oceur in the adjoining district of Aix-la~-Chapelle or Dusseldorf, may sanction a vague suspicion, and nothing more, that the deposit ° might have extended to the low lands of Bonn or Cologne. But this is almost a fruitless speculation. The,newer strata - Brown Coal Formation of the Lower Rheinland. 277 which actually subsist, are referable to a far later geological epoch, to which we shall now confine ourselves. The earliest sub-peried of the tertiary epoch has its date from the time of the breaking up of the chalk basins. In the west and south of Europe, it is indicated by a considerable change which the surface of the globe appears to have under- gone in its constitution. Much new land was raised above the level of the sea, while vast fresh-water basins were constituted, which became receptacles for peculiar deposits. Thus in the Loire, the Seine, the Rhone, and various other rivers, we trace along their respective courses, incontestible evidence of chains of tertiary lakes. The geological features of the Lower Rhine are pretty nearly the same. But, as our investigation is confined to a very limited portion of its banks, the only basin to which I shall advert, as forming a sort of early link in our history, is that of Mayence. The lowest formation characteristic of the tertiary epoch, if we may be allowed to advert to the basin of Paris as a standard of comparison, is that which Brongniart has designated by the name of the J’errain Marno-charbonneua, or d'eau douce infe- rieur ; while a succeeding one is that of the Terrain Marin Tritonien, of which the calcaire grossier is an example. During this united interval, the plain which extends from Hanau to Mayence, and even much farther south, formed a small portion of an inland sea, which originally had been either caused by the simple retreat of pelagic waters, or, upon a dif- ferent hypothesis, the same effect might have been produced by some elevation of the land, whence it was separated from the wider expanse of ocean which bounds the western shores of Europe. Neptune, however, did not uninterruptedly assert his domi- nion over this Caspian lake. Alternations of marine and fresh- water beds, severally calcareous, and even commixtures in the same strata of the shells of land, of rivers and of seas, show that his sovereignty over these waters was disputed. And, if we may judge from the predominance of the fluviatile beds which overtop the series, the mountain-nymphs and river-gods were eventually triumphant. 278 Dr Hibbert’s History of the This lake, during its subsistence, had no communication with the present channel of the lower Rhine, in consequence of a barrier of high land stretching across the present site of the straits of Bingen, and thus filling up the small geographical space intervening between the chains of the Hundsriick and the Taurus. And hence, the Rhine at Bingen was little more than a continuation of the minor stream of the Nahe, which, in taking its rise from the hills of the Hundsriick, is to be re- garded as the original source of the river, which now derives its waters from the far distant and towering Alps. The original elevation of the ancient river, which furrowed for itself a channel along the course of the present Lower Rhine, may ‘be naturally enough supposed to have been very great. There is existing evidence of its having maintained the height of many hundred feet above the present level of the Rhine at Coblentz. Between the present site of Coblentz and Andernach, the river, owing to the basin-shaped disposition of the laud, was expanded into a lake, which was not less than nine miles from north to south, and about twenty miles from east to west. The present gorge at Andernach, through which the waters conveyed by the Rhine now make their escape, did not then exist, in the place of which a barrier of continued cliff rose to a, considerable elevation. The basin thus formed, which I shall name The Andernach Basin, was fed by many streams, of which the Rhine can scarce- ly be affirmed to have, been the principal. The Moselle was then a river of at least an equal importance with the Rhine, deriving its waters from a southerly origin far more remote, the ancient bed of which, where it was lost in the lake of Andernach, being still observable in the high ground to the west of the peak of the Carmelenberg. ' A third subsidiary stream was that of the Nette, which rose from the hills of the Eyfel near the Nurburg; while a fourth was the Wied, which had its source in the Westerwald. The discharge of the overflowings of this lake appears to have been effected in a northerly direction across the barrier of Andernach. And probably not far from the present site of 4 Brown Coal Formation of the Lower Rheinland. 279 ‘Dusseldorf, it was conducted to the ancient sea of the present German ocean. But it may now be remarked, that throughout the whole course of the lower Rhine, from its most early rise in the Hunds- riick mountains down to its junction with the ancient waters of the German ocean, very striking marks of an ancient chan- nel may be detected, which can only be accounted for on the supposition, that the corroding cause was prolonged through the immeasurable lapse of ages contained in a geological epoch. This process which was going on appeared unvaried by any event, except the volcanoes which were kindled in the heights of the Siebengebirge, or in the vicinity of the Laacher-see. In the latter site, violent rents are discernible which the earth sus- tained from elevating forces, accompanied by the shivering of resisting strata, and the developement of a crater; whence pent up gases with tremendous violence issued. But this event was merely the forerunner of more extensive convulsions ;—convulsions which were not confined to this li- mited portion of Germany, but which were apparently employ- ed in elevating submarine lands, by which a considerable por- tion of the German sea, and the lands bounding it, became the site of a spacious fresh-water lake.—This is at least the most plausible theory ;—but, whether correct or not, we must re- pose upon the proofs which will be afforded us, that lacustrine waters rose to a height of at least a thousand feet, and not only filled the channel of the Rhine to the south of the Siebenge- birge, but even extended to the basin of Andernach, in which, as well as in the volcanic crater of Laach and its connected fissures, an earthy deposit may be traced. The commencement of this deposit forms a new sub-period in the tertiary epoch of our history. Here then we shall pause, and inquire what might be the state of vegetation in the lower Rheinland during the interval which we have traced ;—an in- terval when the imagination can dwell upon little more than a rugged assemblage of rocks torn in every direction by moun- tain-torrents, which, at length collecting in one common chan- nel, furrowed out a deep bed for the descending waters. That a flourishing vegetation existed during the united sub- periods of the T'’errain Marno-charbonneua, and the Terrain 280. Dr Hibbert’s History of the Marin Tritonien, there can be nodoubt. The former is cha- racterized by its clays, by its marls, and marly sands; by its gypsum, its lignites, or its amber. It is also the earliest fore- runner of an epoch, which, according to M. Adolphus Brong- niart, differs from every preceding one in the absence of any organic forms foreign to the vegetation which is now in actual progress. Of this formation, however, no indications are afford- ed in the Lower Rheinland; and hence we must conclude, that if it has ever existed, subsequent convulsions have swept all traces of it away. Such is a faint sketch of the geological history of the Lower — Rheinland, previous to the developement of the Brown Coal Formation. I shall therefore consider, Qdly, The Sand and Sandstones of the Brown Coal Forma. tion of the Lower Rheinland. % The brown coal formation may, with various interruptions, be traced from the basin of Andernach along the course of the Rhine, where it occurs on both sides of the river, particularly near the Siebengebirge, covering the declivities of the schis- tose mountains, Along the ridge of hills which extend from Godesberg to Bergheim, it forms deep beds, and is then lost in the flat ground of the lower lands. Its general nature may be summed up in a few words. It consists of a fine sand, which in some few places, by the silice- ous agglutination of its materials, passes into a firm sandstone, succeeded by beds of plastic clay, which occur in different relations of superposition, along with shale, with thin layers of spherosiderite, and much thicker seams of lignite, the latter being commonly named brown coal. The relative age of this formation, which by Brongniart has been referred, though evidently with hesitation, to that of the lower fresh-water beds of Paris, or J'errain Marno-charbon- meux, rather dates, as I have endeavoured to show, from the cessation of the Terrain Marin Tritonien. _Consequent- ly, I refer its commencement to the succeeding period of the Terrain Paleotherien, when great revolutions took place in various parts of Europe, favourable to the developement of Brown Coal Formation of the Lower Rheinland. 281 lacustrine deposits, some of which are not very dissimilar to that of the Brown Coal formation of the Lower Rhine. _ Many details relative to the mineralogical character of this interesting deposit have been furnished by Professor Noeg- gerath of Bonn, who, in his office of superintendant of the mines of that district, has become familiar with all its localities and various appearances. Other incidental notices regarding it are to be found in the works of Professor Steininger of 'Treves, and in the system of geology published by Professor Leonhard of Heidelberg. As the labours of these several writers are much less known in this country than they ought to be, I glad- ly avail myself of any opportunity afforded me to communicate the valuable information which they have imparted, where my own researches may have proved deficient. The lowest member of the brown coal formation is an in- coherent sanp,—showing that it was the earliest deposit of the lacustrine waters. It consists, according to the summary of its characters given by Professor Noeggerath, of fine, round, clear transparent quartzose grains, generally mixed, though not abundantly, with minute silvery scales of mica. Party coloured varieties may be also met with. Grains, for instance, of a common yellow colour are sometimes found in abundance, and impart their hue to a large mass ;—those of a wine-yellow variety are comparatively scarce. Other tints are indigo-blue, blueish-grey, hyacinth, or flesh-colour,—though these are sparing occurrences. Among none of the coloured sands which I have enumerated is to be detected any mineral substance, save quartz. There are, however, occasionally dis- closed certain blackish or brownish particles associated with quartzose grains slightly attrited, which have been judged to be carbonaceous, or, in other words, to have the character of brown coal. The origin of this deposit is a difficult subject of investiga- tion. As this sand is to be traced from the commencement of the basin of Andernach, as far down the Rhine as the low beds below Bonn, where it becomes lost, it is natural to look for its origin to the rivers by which this basin is fed ;—which origin, (infinitely the most simple one to comprehend,) is, if possible, rendered the more plausible, by the indications which 282 Dr Hibbert’s History of the the fine quartzose particles of the sand, and their diffused scales of mica afford, of their having been derived from a primary class of rocks. And, if we are entitled to suppose, that, by the gradual degradation of the original barrier of cliff which filled up the geographical space between the plain of Mayence and the Straits of Bingen, the lower Rhine began about this period to be fraught with materials conveyed from more dis- tant hills, the accumulation of sand in the lower Rhine may _ not only indicate the opening of the communication, but also the drainage of some upper basin, gorged with the fine mate- rials of primary rocks, which the disintegrating operations of infinite ages had accumulated. This theory I consider the more probable, ‘as I have succeeded in detecting on the site of a kindred deposit near the Carmelenberg, and in the crater of the Laacher-see, where a bed of fine sand occurs, frag- ments of limestone detached from the older tertiary beds of Mayence. That during this deposit a vegetable creation wuliinbd upon the lands which were left dry, the commixture which has been detected of the particles of brown coal with those of quartz, gives us every reason to infer. But the most interesting circumstance is, that the close of this deposit furnishes us with the earliest known date when those vast. animals were called into existence, which ranged among the ancient forests and swamps of Europe, before its soil was adapted to the residence of man. In a quarry at Liedberg, in the circle of Gladbach, there wasfound upon a bed of fine quartzose sand, the depth of which was not ascertained, lying between its surface and some super- imposed beds of sandstone, the bones of immense animals, many of which crumbled to pieces on exposure to the air. Among such as were in a state of integrity, was identified a tooth of the Elephas Primigenius of Blumenbach. (Das Gebirge in Rheinland Westphalen, &c. vol. iv. p. 375.) This discovery gave additional weight to the opinion which, from other sources of information, began to be entertained, that animals, whose dawn of existence was referred to the Dilu- vian period, were actually contemporaneous with the Paleothe- rium and the Anaplotherium of the ossiferous gypsum of Paris. 7 Brown Cval Formation of the Lower Rheinland. 283 Whether the latter were beginning to grow extinct when the former were called into existence, is a question of geological history yet remaining to be fully determined. - Such is the character of the deposit of sanp which forms the lowest member of the brown coal formation of the Lower Rhein- land. Other, and succeeding beds, though by no means uni- formly present, are those of sandstone. Tue SANDSTONE OF THE Brown Coat Formation.— This sandstone, which has been particularly described by Pro- fessor Noeggerath, differs in the fineness or coarseness of its ingredients ; in the nature of its cement; and in its degree of firmness or cohesion. | The structure of the finer variety, which is the most preva- lent kind, may be described as granular ; the grains being like those of sand which are connected either by a quartzose, a fer- ruginous, or an argillaceous cement. When the cement is quartzose, which is its predominant character, the cohesion is oftentimes so intimate, that a distinct grafiular structure is not always distinguishable ; the rock having an imperfectly con- choidal and splintery fracture, and approaching to the appéar- ance of hornstone. In other instances, however, the granular particles are so incoherent, that the stone admits of being frit- tered to pieces with the fingers.—The cement may also consist of the hydrous oxide of iron, when the sandstone has less of a spotted yellow than of a streaked colour.—And, lastly, strata are found which have an argillaceous as well as ferruginous ce- ment ;—whence the yellow and brown tints which they exhibit. The structure of the coarse variety of sandstone, which ‘is comparatively rare, is best observed in the Siebengebirge. It is distinguished by fragments of coarse quartz and hornstone often an inch in thickness ;—the fragments resembling the quality of the finer and firmer sandstone described, the grains of which are connected by a quartzose cement. The colour of these coarse ingredients shows various commixtures and shades of blue, gray, and milk white; less frequently, the blendings of gray, black, brown and yellow; and least of all, those of yellow, green, or rose-red. The sandstone of the brown coal formation is nearly hori- 284 Dr Hibbert’s History of the zontally disposed in the form of beds from one to three feet in thickness ;—which in the Siebengebirge exhibit fissures that open wedgewise towards the upper sue and appear like yawning clefts. 3 Vegetable remains have met with conservation in this sand- stone. The Siebengebirge beds inclose pieces of wood-opal and semi-opal a foot or more in extent, which often contain in their clefts coatings of stalactitic milk-white caleedony. The silicified wood which I obtained from this site resembled the internal structure of the coniferous tribe. Other specimens which I procured had well-marked impressions upon them of leaves. Such impressions are —, covered over by a yellow hy- drous oxide of iron. Having at length denesihied the sand and senile of the brown coal formation, I may repeat, that, whenever they are associated with any other members of the brown coal forma- tion, they form the lowest strata. The sandstone is not always the concomitant of the quartzose sand, being, in fact, found only in a few places; but wherever it occurs, it is the upper- most bed. There is again another bed to be noticed, though a very partial one, of a still later date, which has hitherto met with less attention by German writers than it deserves, probably owing to its very obscure relations. This is the loose pebbly mass which surmounts the sand and sandstone. | Kixse1-Grro.tir.—This pebbly bed, named Kiesel-Geréolle, is of interest in showing the altitude to which the deposit brought down by the Rhine or the Moselle attained, when the lacustrine waters into which they flowed were maintaining their high level. While the lighter suspended matters, with which they were fraught, would become diffused through the wide expanse of the basins through which they flowed, larger peb- bles or boulders would not travel far from the course of these streams, but would remain to indicate their ancient route. Thus, thesite where the basin of Andernach first received a por- tion of its deposit from the Moselle is to be detected in the re- markable accumulation of rounded pebbles and boulders of quartz, which are to be observed on the west of the peak of Brown Coal Formation of the Lower Rheinland. 285 the Carmelenberg, in a spot many hundred feet higher than the present low level. of the river; the substance whence these stones are derived having survived a disintegrating process, which has reduced the argillaceous schist it once traversed in the form of veins, to the comminuted state of sand and clay. At Liedberg, however, we find quartz pebbles. surmount- ing a series of beds of sand and sandstone at a much lower level ; the hill being said to rise to no more than 120 to 120 feet above the level of the surrounding plain. To explain this diminution of level, we must return to the geological history of the Lower Rheinland. We have traced in the bed of the German Ocean the rise of lacustrine waters, which not only occupied the valley of the Rhine near Bonn, but even extended to the basin of Ander- nach. During this elevation, the comminuted earthy materials brought down by the Rhine and the Moselle would become first deposited in the basin of Andernach, where these two cur- rents met. Here, therefore, the accumulation would be the greatest ; and, hence, the remains of the deep deposit of sand which we trace in this basin ;—a deposit which has even filled the elevated crater of Laach. . Again,—from the basin of Andernach, the deposit, in propor- tion as we descend along the channel of the Rhine, would naturally dwindle in thickness ; and, accordingly, near Bonn, the boulders which surmount the sand and sandstone appear at a much less elevation. Lastly, if we would, at a still re- moter site, continue our inquiries into the ultimate state of the deposit, we may possibly, if we choose to travel so far, identify some part of it among the deep mass of boulders of an unknown thickness, which the philosopher Leibnitz has recorded as the lowest strata explored ina well sunk near Am- sterdam, to the depth of two hundred and thirty-two feet. I shall conclude my account of the siliceous beds of the Brown Coal formation, by a glance at the strata of Liedberg, to which so frequent a reference has been made :—.it is the ab- stract of a detailed communication on the subject by Professor Noeggerath. In a descending series, the beds were found as follows :— NEW SERIES, VOL. 1V. No. I. APRIL 1831. T 286 Dr Hibbert’s History of the te. ) K iesel Gerélle, mixed with coarse yellow sand, and at the foot of the hill, loam.—Depth 10 to 35 feet. * (6.) Faischerstein. A very incoherent sandstone, 8 to 10 feet thick, pervaded by thin seams of red or yellow ochre. (c.) Haustein. A firmer sandstone, fit for architectural purposes, of a greyish white colour, with yellowish streaks. Passes gradually into the upper bed. (d.) Klinkert. (quartz-sandstone) Of uncommon hardness ; being only fit for ara roads. The fracture splintery and conchoidal.—4 to 5 feet thick. b. c. d. are sandstone beds, conjointly 25 to 3 fathoms _ thick, with an inclination from 4° to 5°. (e.) A beautiful fine, white, quartzose sand. On the surface of it were found bones of extinct animals.—7 feet of the sand have been opened. The depth is unknown. These are all the particulars which it is necessary for me to give, ‘relative to the lower lacustrine beds of the brown coal formation. The period when the vast lake, which apparently occupied a portion of the bed of the German ocean, had at-— tained its summit level, and when the deposit brought down _ by the Rhine and Moselle had acquired its greatest thickness, was probably the close of the particular epoch distinguished in geological history by the formation of the Terrains Pa- leotheriens of Bronguiart. At the same time, the Elephas primigenius, whose remains have been found in the lower tertiary beds of the Rhine, must have been coéval with the ancient animal, the name of which has been imparted to the peculiar deposit of the Paris basin, in which the ossiferous gypsum is included. To the same period we must also refer, 3dly, The deposit.of Plastic Clay which succeeded to the Sand and Sandstone. ‘Concerning the origin of the plastic clay belonging to the brown coal formation;.there is perhaps some little difficulty The disintegrated materials brought down by the Rhine and the Moselle having been diffused through a great expanse of wa- ters, grains of. quartz would, from their gravity, be the first Brown Coal Formation of the Lower Rheinland. 287 precipitated ; while this precipitation would be the greatest in the depressions nearest to the mouths of these rivers ;—in such depressions, for instance, as those which ‘the basin of Ander- nach, or the declivity of Bonn, must have presented during the terraqueous state which I have described. But more levigated particles, of a siliceous as well as of an argillaceous ater! ter, would remain longer suspended in the superambient fluid, and would therefore be borne by currents to considerable dis- tances, and dispersed through the body of the great lacustrine waters. Hence, probably, the thick bed of fine clay which has been traced so far as Holland, and which at Amsterdam ex- ists at a depth of 130 feet, resting upon a still more ancient accumulation of rolled fragments. In such particular lacustrine sites, however, as were not ex- posed to the direct force of currents, much argillaceous matter remaining suspended would tranquilly subside, and form the beds covering substances before accumulated, or even, as we find at Mayen, in the vicinity of Coblentz, constituting an independent local deposit of plastic clay. But the greatest accumulation of plastic clay must have en- sued when the lacustrine waters which deposited the sand and sandstone were retiring. The cause of the extensive drainage which these lacustrine waters underwent, is necessarily veiled in great obscurity. In its operations, it appears to have been extremely gradual, and to have keen continued during the wholeof the succeeding epoch of Brongniart’s Terrains Thalassiques Proteiques ;—an epoch which is indicated by the Nagelflue of Switzerland, the marine deposit of the English Crag, or the Terrain Marin Superieur of Paris. | During the gradual diminution of level which lacustrine waters thus underwent, the Rhine, in its obligation to under- , mine for itself a channel at a reduced level, would, by the force of its currents, remove most of the Joose sand ‘or overlying sandstone which it had deposited, to fill up distant beds of the ocean. In short, it is impossible to traverse the Lower Rhein- land without being convinced, that only a small portion re- mains of a large deposit, which occupied a wide tract of country 288 _-Dr Hibbert’s History of the 7 extending from Coblentz to Cologne, and perhaps much farther north ; the removal having taken place when the retiring wa- ters of a fresh-water lake were doomed to mingle. with the waves of an encroaching sea. / The immense beds of sand or sandstone thus carried away by corroding streams, were in some few sites replaced by other depositions. During the retiring of the waters, limited, basins were in many places formed, favourable to the production of lesser lakes or pools, and being filled with. waters im which — lighter matters were suspended, various local deposits became the result. Ghiy In fine, from these various causes conjoined, the strata. of plastic clay existing in the lower Rheinland are found less in continuous strata than in insulated patches; covering also prior deposits of sand or sandstone. But we may now take a brief glance at the mineralogical character of the plastic clay. This substance may, be regarded as a commixture of the finer particles of silex, alumina, and even other earthy ingredients, with the addition of iron, and, perhaps, manganese. It is also observed to pass into sand, similar to that which I have described as consisting of quartzose grains and minute scales of mica. The colours which it displays are various; the most commen being milk-white, or yellowish. At Mayen, crimson- red variegations are exhibited. Lastly, much of the plastic clay is mixed or otherwise associated with carbonaceous mat- ter, the origin of which I shall shortly consider. Ath, The beds of Cosas Spheerosiderite associated: with Clay, &e. Very little need be said about strata, which chiefly occur in , one site, namely, in the Geistinger wood, north east of the Siebengebirge. : Professor Noeggerath has ameitieds that although spherical and kidney-shaped nodulesof sphzrosiderite or carbonate of iron, from an inch to a foot in diameter, have been found in an isolat- ed form in most of the clay beds of the brown coal formation, whole beds of this ironstone have not before been described. Brown Coal Formation of the Lower Rheinland. 289 The colour of the sphzrosiderite is yellowish grey.” It is compact, and of a flat conchoidal fracture, of a dull aspect, and having a specific gravity of 3.568. When fresh quarried, it shows faint coloured stripes or streaks parallel to the strati-_ fication, but which, by the action of the air, come sharply out, and acquire a reddish brown hue, giving the beds a banded appearance like that of ribband jasper. The analysis is car- bonie acid, 32.231 ; oxydulated iron, 52.128 ; siliceous earth, 5.676; argillaceous, magnesian, and calcareous’ matters with vegetable remains, 9.965. Total 100 parts. Near the Siebengebirge, from 11 to 13 beds of this sub- stance, from a few inches to about a foot in thickness, have ‘been worked. They are eperenietent with strata of clay, as well as of volcanic tufa. . |. &th, The Carbonaceous or Brown Coal Beds. Previous to a history of the brown coal beds, I shall glance “at their mineralogical character, in describing which, I shall avail myself of the excellent account of them which has been published by Professor Leonhard. This distinguished mineralogist divides brown coal into (a) ‘pitch coal, or jet; (6) common brown coal; (¢) bituminous wood or fibrous brown coal; (d) moor-coal; (e) earthy ‘brown coal; (f) alum earth. (a.) Of Piteh-coal, or jet, I shall say little, as its character is ‘well known. It only appears in small layers or nests in the common brown coal. ~- (6) The common brown coal, which is the predominating species, appears in beds of great thickness and extent, and is chiefly distinguished by the form of wood being only in part recognizable, by the texture being only occasionally fibrous, -or by the complete absence in it of the well known fibrous “structure of wood. Its specific gravity is 1.28. It is black- ish brown and compact. Its fracture is earthy, and approach- ing to the conchoidal, and it has a greasy lustre. In burning, -it first gives out a little smoke, but afterwards brightens up with a tolerably pure flame, yielding an ash very like that of wood, but more earthy, and containing, somewhat plentifully, iron and potash. It yields from 45 to 50 per’ cent. of - earbon and earthy materials, and 55 of volatile matter; leav- 290 . ~~. Dr Mibbert’s History of the ing, after being consumed, from six to eighteen parts of a re- sidue. - (c.) Bituminous Wood, or Fibrous Brown Coal. —This ‘a stance marks the first degree of change from an organic to an inorganic substance, in which, the history of brown coal is to be read. It is of a blackish brown colour, showing: distinct fibres of wood. The bark and annual rings are not unfrequent- ly distinguishable. The stem, branches, or pieces of the roots are in general flatly pressed. The plants to which these re- mains are referable have been already fioticed. Beech, oak, the fir cones of the Pinus picea, and more rarely of the Pinus abies, also Sumach, (Schwartzholz) and birch.’ There is also often found in the same bed with the lignites, innumerable seeds of the Erica vulgaris, and even the remains of earth- beetles. The bituminous wood is susceptible of some few. modifications. At the Piizberg near Friesdorf it contains a more or less plen- tiful diffusion of particles of clay ironstone, and, in the same place, a substance like leafy anthracite appears in dark colour- ed layers. It has also been found, though elsewhere, pene- trated by sulphur. (d.) Moor-coal, (Moorkohle.) Specific gravity 1.2 to 1.8; colour between pitch-black and blackish-brown ; compact ; fracture even; lustre dull or glimmering. This substance has been considered as a decomposed brown coal without any lig-. neous structure. But its character is best recognized by re-. garding it as composed of reeds and swampy plants. (e.) Earthy Brown Coal.—This has been described as no- thing more than a common brown coal, decomposed to a high- er degree than moor-coal; to which belongs the Cologne umber, or Cologne earth. It has also been regarded as a bitu- minous substance consisting of destroyed vegetables, such as seeds, and leaves, and stalks of swamp-plants, and rinds of the branches of trees. The earthy brown coal is remarkable for containing, the trunks or stems’ of bituminous wood, and, according to M. Faujas, the remains of Cervi and other animals. Both the moor and earthy brown coal occur in beds of great thickness and extent, only yielding in this respect to the com- mon brown coal. Brown Coal Formation of the Lower Rheinland. 291 (f.) Alum Earth ( Alaunerde.)—This is nothing more than - aclay, rich in alum, through which much bituminous matter is diffused. Or, rather, it is a clay with which vegetable mat- ters have been mixed. That which I examined at Altwied was of a bluish, or of a brownish colour. German geologists have also enumerated other varieties of brown coal, as the Bast-coai, consisting of the twisted rinds of pines and alders, and the needle-coal. But as it is doubtful if they exist in the Lower Rheinland, and as the distinction is at best a subordinate one, I shall pass them over. The thickness of the brown coal beds is various. One Ger-— man author has affirmed that they do not exceed 6 or 8 feet ; while another, who appears more familiarly acquainted with them; mentions beds 18, 24, 26, or even 32 feet thick. 6th, The origin of the Carbonaceous, or Brown Coal Beds. So late as the period indicated by the ossiferous gypsum or _ paleotherian beds of Paris, the west of Europe enjoyed a temperature so far exceeding that which at present prevails, as to render it the region of palms. This is proved by the nu- "merous arborescent monocotyledons which have been found in the brown coal beds of the Lower Rheinland. Geologists have at various times supplied us with the names of such remains as have been thus entombed, to many of which it has been found rather difficult to assign a correct place in the vegetable kingdom. The list of them which I have collected is as fol- lows: Cocos Faujasii, found at Lieblar m the Cologne district ; Carpolithes Areceeformis, C. cocoiformis, Cologne district ;. C. amygdaleformis, C. pisiformis, C. pomarius, C. lenticularis, Osberg, not far from Erpel ; Endogenites ? bacillaris, Cologne district. | In the higher lands, however, from which the Rhine derived its origin, there is every reason to suppose, as I shall very soon show, that a perfectly different vegetation, corresponding to a colder climate, subsisted. The description of trees .which flourished, comprised the Pinus. picea or the Pinus abies, the beech, the oak, or the alder. With these, the common heath (Erica vulgaris) was contemporary. 292 Dr Hibbert’s History of the During the period when the lacustrine waters of the Lower Rheinland were maintaining their high level, vegetation ap- Ly to have made some little advance ;—which is indicated by he diffusion of carbonaceous matter through some of the lower beds of sand, while the silicified wood of the Siebengebirge sand- stone points to the drifting which had then commenced of the — Coniferze of Alpine heights. At the same time, new races of Mammalia were called into existence ; among which were the Elephas primigenius, the rhinoceros, the hippopotamus, and Cervus Euryceros,—animals severally adapted to the early la- custrine, or marshy state of the surface of Europe. _ “ The period, however, when the most profuse indications are a afforded of a Apatibin vegetation, may, with much reason, be referred to the era of the Terrains Protéiques of Brongniart. The climate of the Lower Rheinland must then have gra- dually cooled, so as to approach that of the temperate regions of the globe. This may be inferred from the proofs which are afforded that the oak, the beech, and other forest trees of less warm climates, were once contemporaneous with the fossil palms of Cologne, which they far exceeded in abundance ;—a circumstance which renders it highly probable that the tempe- rature of this district nearly resembled that of the southern coasts of Italy, or of Spain, which can still tolerate the growth of plants of opposite regions. Thus, at S. Remo, in the Genoese States, dense plantations of palms had long subsisted, which were latterly encouraged for the sake of the branches required for the papal processions of Palm Sunday. And at Murcia, the palms which many ages ago had been particularly noticed by Pliny, continued to be fostered for the sake of a similar pious traffic with Italy, so late as the year 1775. “ We stop- ped at Elche,” says the intelligent Swinburne, ‘ a large town belonging to the Duke of Arcos, built on the skirts of a wood, or rather forest, of palm-trees, where the dates hanging on all sides in clusters of.an orange-colour, and the men swinging on bass ropes to gather them, formed a very curious and agreeable scene. The palms are old and lofty ; their number is said to exceed two hundred thousand. Many of the trees have their ‘branches bound up to a point, and covered with mats, to prevent the sun and wind from getting to them.” Brown Coal Formation of the Lower Rheinland. 293 ~ But to return to our history. - There are still other circumstances to be kept in view, if we — would fully explain why the remains of Coniferae, of the beech, the oak, or the alder, are so much more abundant in the brown coal beds, than those of arborescent monocotyledons. Much of the vegetable matter, indicative of temperate rather than of tropical regions, must have been brought down by the Rhine during periodical or occasional floods, from the remote and elevated lands of the European Alps, where the tempera- ture differed greatly from that of the low declivities of the Rhein- land; having been deposited while the lacustrine waters main- tained their high level, after the manner of the immense accu- mulation of drift-wood incidental to the embouchures of the great rivers of North America, which has been transported from the region of the pine to that of the fig or the olive. This view will be confirmed by the circumstances under which much of the timber of the fibrous brown coal beds is found ; while, on the other hand, some trees have been disin- terred, consisting of palms as well as oaks, which show that they must have flourished simultaneously. Thus, at Lieblar, near Cologne, a palm was found in an erect position, and, under similar circumstances, the dicotyledonous plants of temperate _ regions have been discovered. - We must conclude then, that the same floods, which, from remote elevations, differing considerably in temperature, would transport the spoils of overgrown woodlands, would also under- mine the densely planted margins of contiguous embouchures ; —or, that the swollen Rhine, in its impetuous course, would sweep away the foundations of much adjacent soil; causing land-slips, or even bearing with it numerous floating islands, with multifarious trees still clinging in an erect posture to their native soil; and that these, when their further progress was resisted by shoals or any other impeding cause, would: be mingled with the far imported drift-wood of alpine heights. This view would meet with some support, if it could be shown that trees occur mingled indiscriminately in the same bed in both a vertical and horizontal position ; the former in- dicative of a growth in situ, and the latter of distant trans- portation. 294 Dr Hibbert’s History of the An observation of this. kind has, indeed, been already wee. Professor Noeggerath has recorded, that at the Piitzberg, near Friesdorf, the upper beds consist of variously alternating bed of earthy brown coal, bituminous wood, alum earth, and pot- ter’s clay, in which are found isolated trunks of trees, some of them resembling the oak, of enormous thickness, varying from seven even to twelve feet in diameter, and destitute of their upper parts, which appear as if broken off or split. While some of these trees are horizontally imbedded, others are found standing upright, and passing through all or most of the associated beds of brown coal, alum earth, or potter’s clay. Tth, The alternations of beds of Brown Coal with those of Plas- tic Clay. The occurrence of beds of brown coal alternating with plas- tic clay, suggests an investigation of other circumstances under which the ancient vegetation of this district was developed. It has been assumed, that, at the era of the Terrains Pro- teiques, the lacustrine waters of the Lower Rheinland had be- gun, from some obscure geological causes, to undergo a gra- dual and long-continued process of drainage, during which, a considerable waste or removal took place in the beds of sand, sandstone, and plastic clay, successively deposited. Being li- able to be acted upon by the periodical or extraordinary inun- dations to which all large rivers are subject, considerable re- movals of the beds, particularly of the upper ones, would ensue. ‘Thus, at Roisdorf, loose blocks only remain of the continuous bed of sandstone which reposed upon the sand, and, at Friersdorf, uo trace whatever of the same has been left. Nay, in some places, the waste appears to have extended to a much greater depth ; removing the subjacent sand altogether. The proof that the vegetation of the Lower Rheinland must have flourished most during this succession of changes, is, that the lowest brown coal beds in the neighbourhood of Cologne may be seen to rest upon the loose sand from which the sand- stone has either been removed altogether, or appears in the form of severed or insulated blocks. This is shown at Rois- dorf, where, upon the loose sand from which the sandstone has been removed, rests bituminous clay ; or at Briihl, where, un- 4 : Brown Coal Formation of the Lower Rheinland. 295 der similar circumstances, repose powerful clay and brown coal beds. © In short, there is reason to suppose, that during the pro- "tracted retreat of lacustrine waters, while numerous forest trees, such as the oak, the beech, or the pine, began to occupy ‘the firmer shores which were slowly laid bare, sandy or mud- formed tongues of land and islets were developed, in the soft materials of which palms fixed their roots, along with an abundance of aquatic reeds or sedges, the debris of which may be traced in the thick existing beds of earthy brown coal. The vegetation which had thus taken root, would, in the next place, be liable to be submerged during adventitious pe- riods of inundation, beneath the materials of the sandy or loamy beds thus removed; and, more particularly, beneath the beds of plastic clay, which, in forming the upper layers of the la- custrine deposits of the Rhine, would be the first removed ;— while accumulations of drift-wood, transported by the rush of inundations, and covered over by renewed earthy deposits, would induce the frequent alternations of clay and brown coal beds, which are so observable in the district of the Lower Rheinland. Two examples of these alternations, on the authority of Professor Steininger, may be quoted, the beds of which are given in a descending series. At Frirsporr. At Watwerserc, Liestar, AND Bruut. -Gerdlle, (gravel,) Gerdlle, (gravel,) -Brown coal, Brown coal ;'26 to32 feet thick, Potters’ clay, Potters’ clay ; unknown depth. New brown coal floetz; not worked through at 20 feet. 8th, The beds of Shale alternated with those of Brown Coal. Still other effects would result during the retreat of the la- custrine waters. Much of the surface of the sandy or clayey deposits, which had been left exposed by the diminution of level which the Rhine had undergone, would present concavi- ties of greater or less depth, which would be filled with the waters which remained upon the occasion of their emergence. 296 . ‘Dr Hibbert’s History of the Into these minor lakes or pools, generally formed by depres- sions made in the upper strata of plastic clay or brown coal, the disintegrated materials, derived from the gradual waste of adjoining hills of primary schistose strata, appear to have been: washed ; and these, mingling more or less with the bituminous matter of brown coal beds, or co-existing vegetation, or with the earthy particles previously suspended in the waters of these small basins, appear to have given rise to corresponding strata, which are to be regarded as little more than varieties of com- mon shale, generally bituminous. : German geologists have, however, subjected these strata to very forced distinctions, as into (a) Klebschiefer, adhesive slate; (b) Polierschiefer, polishing slate or Tripoli; and (c) Papier- kohle, paper coal. (a.) Klebschiefer, Adhesive slate, so named from adhering to the lip when moist, has been described as of a light yellow- ish grey, greyish white or smoke-grey colour, thin and slaty in its texture, and in its fracture flatly conchoidal ; easily tri- turated, and shivering readily in the direction of its Jamine. Menilite is sometimes inclosed by it in small roundish and flat- tish nodules. The analysis given of Adhesive slate is so vari- ous that it is not worth stating. It must necessarily differ in different places, according to the ultimate nature of the sub- stances from which, as a shale, it is derived. (b.) Polierschiefer, Polishing slate or Tripoli.—I cannot find that this substance differs materially from adhesive slate. It is described as of a yellowish or reddish white colour, ea- _ sily separable into thin and slaty laminew, which are so ten- der that they may be rubbed to a powder by the fingers. ‘The notion of its having assumed this condition from the operation of fire, is not on the present occasion to be entertained ; the effect being more like that of dryness or weathering. Both the adhesive and polishing slate‘ are described as ab- sorbing water with avidity, and throwing out air-bubbles. — (c.) Papierkohle, Paper coal.—This is of a blackish brown colour, with a dull, as well as glistening lustre; divisible into uncommonly thin and tender leaves, whence its name'of a coal. 6 Brown Coal Formation of the Lower Rheinland. 29% All these three substances, viz. adhesive slate, polishing slate, and paper-coal, pass into each other. , Such is the character of the strata which form the beds in- cidental to the pristine pools in which they were deposited. While the process was going on, these basins were stored with numerous fish, frogs and lizards, of species still existing, which are now discovered interposed and flattened between the folia of the shale which I have described. Ina quarry near Unkel, I was so fortunate as to obtain the impression of an insect about the size of a common bee, and resembling an individual of the Hymenopterous, or perhaps Dipterous order. Plentiful impressions of leaves and trees also appear under similar circumstances, which, as well as the beds of brown coal, associated with the shale, seem of an extraordinary freshness ; having been apparently derived from the later plants which flourished around the margins of these pools. I shall conclude this account of the associated shale and brown coal beds, with the following section of a pit near the Siebengebirge, from the surveys of the German geologists. The beds are stated in a descending series: Loamy soi! containing brown coal. Loam strata. Brown coal, consisting of the carbonized wood of trees. Shale (Adhesive and Polishing slate;) containing impres- sions of fresh-water fish and plants. Paper coal, with impressions of fish and plants. Greyish-white potters’ clay; the lowest observed bed. 9th, The volcanic eruptions which were coéval with the Brown Coal Formation. Upon this portion of our geological history, I shall say very little. It has been explained, (page 279,) that trachytic eruptions preceded the commencement of the brown coal formation. Sub- sequently, the phenomena took place of mud volcanoes, simi- lar to those which are still recognized in South America ;—and that these were contemporaneous with the lacustrine deposits of the Rheinland, is shown in various sites. It would appear from a section at Queggstein in the Siebengebirge, that the overflow of mud, (named trachyte conglomerate,) took place 298 - Dr Hibbert’s History of the at the close of the sandstone deposit, which this volcanic pro- duct covers. At the Ofenkulerberg, beds of trachyte conglo- merate contain a layer of altered leaves and other remains of plants; and at the Langenberge, altered wood may be found under similar circumstances. At Geistinger, where twelve or more thin layers of spherosiderite are alternated with clayey beds, chiefly derived from decomposed trachyte, the whole is surmounted by slaty brown coal and paper coal ; the latter con- taining impressions of leaves and of fish. The later eruptions of basalt which took place in the Rhine district appear to have been contemporary with the upper beds of brown coal; for at Utweiler a flow rests upon the same, the substance of which has been converted into a sort of pitch-coal or jet. Lastly, basalt blocks are found in the Gerolle which covers the Brown Coal formation.—(See Noeggerath’s Rheinland Westphalien,. vol. iv. p. 383, &c. and Steininger’s Memoirs, for farther de- tails.) 10th, Sequel of the History of the Plants which flowrished at — the time of the Brown Coal Formation. Our geological history of the brown coal beds must now be considered as brought down to the close of the period of the Terrains Protéiques, or upper marine formations of the London- and Paris basins. At this time, lacustrine waters had subsided before the renewed inroads of the sea; while the corroding torrent of the impatient Rhine, by removing most of the soft materials of the brown coal formation, and transporting them to the deep bed of the German ocean, had again occupied the channel which it had formerly excavated for itself through firmer strata of argillaceous schist. It is highly probable that at the close of this epoch, the climate of the Lower Rheinland had been deteriorated ; that its palms had disappeared ;—the oak, the beech, or the pine having remained in inci pos- session of the soil. A succeeding epoch, to which Brongniart has’ referred his Terrains. Epilymniques, is characterized by the upper fresh- water beds of the Isle of Wight or of Paris, by the ancient Travertino of Italy, and perhaps by such deep beds of com- mon peat as can be shown to have subsisted immediately pre- Brown Coal Formation of the Lower Rheinland. 299 ceding the great diluvial deposits of the north of Germany, or of the British islands. Upon the heights of the Veen, situat- ed to the west of the Rhine, an ancient deposit of clay is sur- mounted by beds of turf to the depth of sixteen feet. The lowest of these, which contain wood of an obscure character, much resemble beds of true brown coal, of which they were probably the immediate successors. - In this instance, however, there has been no interruption whatever to the vegetation in- dicated by these beds from any diluvial waters, although, in the valley of the Rhine, traces of such a catastrophe are evi- dent,—particularly in the immense quantity of transported mud, named Britz, which has been deposited near the present site of Andernach, though to no greater a height than five or six hundred feet. The vegetation of more considerable elevations must have therefore remained uninterrupted. Ac- cordingly, on the Hohe Veen, in the strata of turf succeeding to the deepest ones described, birch-wood, fir-cones, or hazel- nuts are found, while the uppermost layers of hard or swampy moss connect the series of beds with the vegetation of the pre- sent day. And thus, also, may the modern forests of the Rhein- Jand boast a derivation from the ancient stock which is to be recognized in the fossil wood of the brown coal formation, and which has an antediluvian date, fully as remote as that of the Paleotherian beds of Paris. In concluding this very difficult history, it might be expect- ed that I should describe the economical uses to which the . different beds of the brown coal formation are applied. But as the object of this memoir was a very different one, I shall content myself with the following brief statement. ° Some of the sandstone is used for architectural purposes, but the hard- er variety is the most valuable, being so much indurated by a siliceous cement as to be applicable to the making of roads. The extraction of the purer clay, which is in great demand as a pipe-clay, or as a potters’ clay, takes place in deep pits at Bannerhof, at Dreckenach near Coblentz, and at various other places. The lignites have long been in popular use as a fuel, while the variety named the earthy brown coal has been work- ed for the valuable pigment named burnt umber, or Cologne 300. Dr Brewster’s Observations on the a -earth. But of late years, the brown coal beds have acquired more importance from their affording the materials for the ex- tensive alum-works of the neighbourhood of the Siebengebirge. The most powerful strata of this deposit were found out near. ly forty years ago, and it is honourable to the Rheinland to record, that a handsome monument has been erected near the mines as a tribute to the humble individuals to whom the country has been indebted for the discovery. From this me- morial I copied the following inscription: Dem ANDENKEN DES ERSTEN FINDERS DER HARDTER BRaUNKOHLEN-LAGER, JOHANNES KirscHBAUM UND SEINER EnEerrau Anna Mac- pDELENA Liitz. [To the memory of the discoverers of the Brown Coal deposit of the Hardt, John Kirschbaum, and.his wife, Anna Magdalena Liitz. | This tribute displays the popular feelings of the davies, and is strikingly contrasted with the neglect which is exhibited on the British shores for even far more important benefits ; a neglect which is now operating to the serious prejudice of the kingdom, by annually thinning the ranks of useful or scientific contributors. ; Art. [X.—Observations on the Mean Temperature of the Globe. * By Daviv Brewstxrr, LL. D. F. R. S. Lond. & Edin. Ir no provision has been made by the Great Author of Na- ture, for equalising the light and heat projected upon the dif- ferent bodies of our system, we may consider the earth as re- ceiving, from the direct action of the solar rays, a degree of heat, intermediate between the condensed radiations sustained by Mercury and Venus, and the attenuated warmth which reaches the remoter planets. The heat which our globe thus acquires from its locality in the system, is again tempered by ‘the obliquity of its axis, and is distributed over the same pa- rallels of latitude by its daily rotation. When the sun is in the Equator, his rays, beating on the earth with a vertical in- fluence, impart to it the full measure of their action; and as his meridian altitude decreases, their intensity suffers a corre- * Read before the Royal Society, February 1, 1820. Mean Temperature of the Globe. 301 sponding diminution. The burning heat, at the Equator be- comes moderated in higher latitudes. In passing through the Temperate Zone, it declines with great rapidity, and between the’ Aretic Circle and the Pole, the rays of the sun are unable even to temper the piercing ae which reigns in these inhos- pitable regions. This gradation of iulemnds so obvious to the sensations of those who have visited southern climates, is still more dis- tinetly indicated by its physical and moral influence. The arid plains of a tropical climate, where vegetable life is almost extinguished by excessive heat, gradually shade into the more luxuriant regions of the vine and the olive. The'mild and uniform temperatures of Spain and Italy, are again followed. by the variable climate, and the more verdant kingdoms in. the north of Europe. Then succeeds the region of blighted vege- tation, where nothing can exist but the birch and the pine; and the chain of vegetable life terminates in the hoary desolation of the Arctic Zone. The progression of climate is no less distinctly marked by the developement of the human faculties. Indolent, and im- _patient of thought under the debilitating influence of a sultry atmosphere, man begins to unfold his capacities as he is remov- ed from the Torrid Zone. In more temperate climates, he cultivates those faculties which do not lead to very rigorous application ; and under the invigorating influence of a. colder sky, the mind attains that maturity of its powers, which fits it for the most abstract and profound speculations. From this’ region, distinguished as the seat both of ancient and modern civilization, the mind again sinks under the torpor of extreme cold, and the distinctive characters. of our species disappear among the diminutive inhabitants of the Polar latitudes. ’ The investigation of the mean temperature of the earth, connected, as it thus appears to be, with many interesting in. quiries of a moral and physical nature, has not been pursued with the’same zeal as other branches of knowledge, Long after the invention of the thermometer, no attempt had been made to apply it to meteorological purposes ; and though, for more than half a century, its indications have been registered in many parts of the world, yet the observations with it have NEW SERIES, VOL. Iv. No. 11. APRIL 1831. U , 302: Dr Brewster’s Observations on the commonly been guided by no settled principle, and: are, there- fore, frequently unfit for the purposes of generalization. \Phi- losophers were satisfied with deducing a law of temperature from theoretical considerations; and disdained the humbler and more laborious task of interrogating the mass of facts which had been accumulated -by zealous and active observers. The first person who attempted to deduce from observation a general expression for the mean temperature, at all latitudes, was the celebrated astronomer Tobias Mayer of Gottingen. Assuming that the heat varies as the square of the sine of the latitude, he obtained the formula T = 58° + 26° x Cos. 2 Lat., in which 58° is the mean temperature of 45° of north latitude, and 26° the difference between the temperature of that parallel and the Equator. M. Lichtenberg, the editor of Mayer’s pos- thumous works, applied this formula to 13 observations of mean temperature made between the Cape of Good Hope and Stockholm, and their agreement was considered at that time to be remarkable. The sum of all the errors was 26°.8, or a little more than 2° on each observation ; but as the errors in excess amounted to 22°. 3, while those in defect were only 4°.5, it should have been obvious that the formula was founded upon an incorrect assumption. The formula of Mayer was implicitly adopted by Kirwan, in his able work On the Mean Temperature of tie Earth ; and has been more recently brought forward, as connecting together, “in a most harmonious manner,” the results of dis- tant temperatures, although the fine series of observations, col- lected by Humboldt, had ‘demonstrated its inaccuracy, and proved, that even’ in the parallel of 63°, it erred in excess no less than 9° of Falirenheit. The beautiful memoir of Humboldt on the Jsothermal Lines, or lines of equa] temperature, and on the distribution of heat over the globe, has given a fresh impulse to this fundamen- tal branch of meteorology, and will, no doubt, introduce a new degree of precision into those loose and indefinite records of temperature which have been so generally accumulated in every part of Europe. . In attempting to reconcile the formula of Mayer with the observed results as given by this celebrated traveller, I expected to succeed, at least for the western re- Mean Temperature of the Globe. 303 gions of the Old World, by the adoption of more correct co- efficients; but as I proceeded in the inquiry, I saw that the principle of the formula was entirely irreconcileable with well established facts, and I therefore sought for a law different from the duplicate ratio of the sines. In comparing the temperature of the Equator with that of 45°, and with that of the highest latitude in Humboldt’s se- ries, it was obvious that the cold increased much more rapidly towards the Poles than had been believed; and upon extend- ing the comparison to the intermediate temperatures, I found that the mean heat of any place was well represented by the radius of its parallel of latitude, or, in geometrical language, that the temperatures varied with the cosine of the latitude. In expressing this law I have assumed 815° as the mean tem- perature of the Equator, the very same number which Hum- boldt has preferred as the mean of various results under distant meridians. * The formula therefore becomes T = 813 Cos. Lat. The following table contains the observed mean tempera- tures of thirty-one places, situated between the Equator and the parallel of '70° of north latitude, together with the calcu- lated results, as given by the preceding formula, and by that of Mayer, in its latest form. TasLe oF MEAN TEMPERATURES. Obs. Cale. Mayer’s Lat. Mean Mean Diff’ Formula. Diff. . Temp, Temp. Equator, 0.0 81.50 81.50 0.00 842 2.7 4 Columbo, 6.58 79.50 80.90 ° 140+ 83.4 3.9 4 Chandernagore 22.52 75.56 75.10 046— 76.3 0.74— Cairo, $0 .2 72.82. 70.56. 1.76—— 71.1. 1.814 5 Funchal, 82.37 68.54 68.62 0.084+ 69.0 0.46+ Rome, 41.54 60.44 60.66 0.22+ 60.7 0.36+4 Montpellier, 43.36 59.36 56.03 0.33— 59.4 0.044 | Bourdeaux, 44.50 56.48 57.82 1.34+ 59.0 2.524 Milan, 45.28 57.18 58.28 1.10+ 57.7 0.524 * Additional grounds for this assumption will be found in this Journal, No. xi. p. 117, and No. xv. p. 60. ¢ 304 Dr Brewster's Observations on the ho pe eg Obs.:.. Cale. Mayer's Lat. . Mean Mean Diff. Formula. Diff. © ~ emp. Temp. » 2 SSSR IES 10 Nantes, 47.18 54.68 55.35 0.67+ 56.10 1.424 St Malo, 48.39 54.14 53.85 0.29— 5480 0.664 Paris, - 48.50 51.89 53.65 1.764 54.60 2.714 Brussels, 50.50 51.80 51.47 0.33— 52.90 1.10+ Dunkirk, 51.2 5054 51.25 O714+ 52.70 2.164 15 London, ~— 51.30 50.36 50:74 0.38+ 52.30 1.94+4 Bushey Heath, 51.37% 51 ‘2 50.68 0.62— * 9 = Kendal, 54.17 46.02 47.58 1.564 49.8 3.784. New Malton, 54.10 48.28 47.53 0.75— 49.9 162+ — Lyndon, 54.34 48.90 49.37 O474+ 49.5 0.604 20 Dublin, 53.21 49.10 48.65 0.45— 50.6 1.504 Copenhagen, 55.41 45.68 45.95 0.27+ 486 2.924 Edinburgh, 55.57. 46.23 45.64 0.59— 48.32 2.09+ Carlscrona, 56.16 46.04 45.46 0.58— 48.2 2.164 Fawside, 56.58 4430 44.26 0.04—_ 47.5 3.204 25 Kinfauns, 56.233 46.20 45.12 1.08— 47.9 1.704 ‘Stockholm,. 59.20 42.26 41.57 0.69— 45.5 3.244 Upsal, 59.51 42.08 40.94 1.14— 45.1 3.024 Abo, 60.27 40.00 40.28 0.284 446 460+ Umeo, 68.50 33.08. 35.96 288+ 42.1 9.024 30 Uleo, 65 .3 33.26 3438 111+ 413 8.044 This singular agreement between the observed and caleula- ted results, and the equilibrium of the positive and negative errors, shows that the formula embraces the leading causes which affect the mean temperature of the west of Europe. ‘The sum of all the positive errors is 13°.12, and the sum of the negative errors 9°.11; and their total amount is 22°.23, which gives only an average error of ;°,ths of one degree of Fahrenheit upon each observation. The results of Mayer’s formula give all the errors positive except one, and their sum is no less than 70°.7, being 2°.3 for each observation. The error of the formula becomes so great as 9° between the parallels of 60° and '70°, which proves, in the most convincing manner, that the temperature of 32°, which Mayer assigns to the North Pole, is very far above the ‘truth. The formula which I have given above makes the‘po- lar temperature so low as sero, or 0° of Fahrenheit’s seale, dif- fering 32° from the preceding measure; but the circumstance ~ Mean a toa hid o the Globe. 305 of its sapiedenting with accuracy the mean temperatures at very high latitudes, inspires us with some confidence even in this extreme result. In this state of uncertainty respecting the sirchalile tempe- rature of the North Pole, and of the accessible parallels be- tween 70° and 80°, I proposed to examine the most northern meteorological journals, with the view of finding some general rule by which the mean temperature of the year might be de- duced from one or two months observations. I had previous- ly communicated my formula to Mr Scoresby, and requested * from him some information respecting the temperature of the Greenland Seas; and I had the satisfaction of finding, that this subject had engaged his most particular attention, and that he had actually deduced the mean temperature of the parallels of '76°.45’, and 78°, from a series of 650 cnaertailires made by himself, in mine successive years. * In the latitude of 76° 45’ he found the mean temperature to be 18° ,8°,dths. My formula makes it 18° foodths, devia- ting only 3,%dths of a degree. ‘. In the latitude of 78°, Mr Scoresby found the mean tempe- rature to be 16°, dths. My formula makes it 16°,%%,dths, deviating only ,§,;dths of a degree. Mayer’s formula makes the mean temperature of these parallels above 34°, erring no less than 33° upon both observations, whereas the error of my formula is only }th of a degree. It appears, then, from the evidence of direct observation, that the temperature of the North Pole must be considerably lower than 16° ,°,°,dths, and must therefore be more correctly indicated by the new formula than by that of Mayer. Mr Scoresby has attempted, by a very ingenious analogical pro- cess, to deduce the temperature of the Pole from that of 76° 45/. He considers the difference between the actual tempera- ture of that parallel, viz. 18°.86, and the temperature given by Mayer’s formula, or $3°.8’, as an anomaly produced by the frigorific influence of the ice; and having found what this ano- maly should be at the Pole, he subtracts it from Mayer's po- * This interesting investigation is now published, in Mr Scoresby & UX- cellent Account of the Arclic Regions, vol- i. p. 356. 806 Dr Brewster's Observations on the lar temperature, in order to obtain the real polar temperature, which he thus finds to be 10°. This result, however, is obvi- ‘ously too great, upon Mr Scoresby’s own principle; for since Mayer’s formula errs greatly in excess in those parallels where there is no accumulated ice to produce an anomaly, it must — give at least an equal error in excess for the parallel of '76°.45/. Now, this error in the latitude of 63° and 65° in Lapland i is 8°; and therefore calling it also 8°, which is far too low for the latitude of '76° 45’, we have for the mean temperature, un- influenced by the ice, 33°.8 — 8°.0 = 25°.8 ; from which. sub- tracting the polar anomaly of 21°, as computed. by Mr Scores- by, and we obtain 4°.8 for the mean temperature of the Pole. In the preceding paragraphs, we have compared the results of the formula with the temperatures ef individual places, which must often be influenced by local causes. We shill therefore compare the formula with the temperatures of the four paral- lels of 30°, 40°, 50°, and 60°, which Humboldt has deduced from a great variety of observations, and which he considers: as well established. Lat. N. Observed Calculated Differences. Mean Temp. Mean Temp. 30° 70°.52 70°.56 0°04 + 40 63.14. 62.43 0.7] — 50 50 .90 52 .39 1.49 + 60 40.64 40.75 O14 Scoresby 76 45’ 18.86. 18.68 0.18 — Do 78 16.99 16.95 0.04 — The differences between the observed and calculated tem- peratures, both in this and the preceding Table, are frequently owing to the circumstance of the thermometer having been observed at two periods, the average of which does not give the mean temperature of the day. ‘lhe Reverend Mr Gordon has found, from a series of very accurate observations, that the mean temperature will be obtained most correctly in this country, when self-registering thermometers are not used, by observing at 10 o’clock in the morning and evening ; and it is highly to be desired that this principle should be adopted in all our meteorological journals. Another source of difference Mean Temperature of the Globe. 307 arises from local causes, which often occasion a difference of temperature under the same latitude. In the case of Edin- burgh, for example, the mean temperature, deduced from Mr Playfair’s observations, is 47°.8*, differing considerably from the formula, while the mean temperature, according to the obser- vations of Messrs Miller and Adie, is 46°.23, + agreeing very nearly with the calculated results. Hitherto we have considered only the temperature of the Old World, as determined under meridians passing through the west of Europe; and previous to actual observation, it was reasonable to infer, that under other meridians the heat would follow a similar law of distribution. The testimony of travel- lers, however, soon corrected this hasty inference ; and as the condition of more distant climates was better known, the seve- — rity of a Canadian and a Siberian winter became proverbial. Notwithstanding this evidence, Mayer, and Kirwan, who adopt- ed his formula, have considered it as universally applicable ; and Mr Leslie has maintained, on the authority of a few in- sulated facts, that the average temperature of the Old and New World will be found the same. t These speculations, however, have been completely over- turned by the researches of Humboldt. He has shown, that though the temperature of the Equatorial regions is nearly the same under all meridians, yet in higher latitudes it declines rapidly in the new world, and under the eastern meridians of Asia. In the three first columns of the following Table, he has given the differences of temperature for the eastern and western hemispheres, under the parallels of 30°, 40°, 50° and 60° of north latitude. Pas Temp. Old Temp. New _ Diff. between * ‘World obs. World obs. O.and N. World. . 80° 70°.52 66°.92 3°.60 40 63 .14 54 .50 8 .64 50 50 .90 37 .94 12.96 60 40 .64 23 72 16 .92 The difference of temperature of the Old and New World is * See Note A, p. 319. + These observations were made in Merchant Court, 230 feet above tlic level of the sea. t Edinxburgh Encyclopedia, Art. AmEnIcA, Sect. Climate of America, vol. i. p. 614, 308 Dr Brewster’s Observations on the nearly 4° in the parallel of 30°; 9° in the parallel of 40°; 18° in the parallel of 50°; and 17° in the parallel of 60°. The determination of the temperature of North America, enables us to. approximate with more certainty to the degree of cold which exists at the North Pole; and as this question must always possess considerable interest im relation to any attempt that is made to explore these icy regions, I would re- quest the attention of the Society to the nature of the argu- ment by which I conceive that we may ascertain the mawimum _ limit of the Polar temperature. In the,Old Continent, the mean heat at 60° of letiunde i is 40°. In 78° of latitude, Mr Scoresby makes it 1'7°, and thence infers that it must be 10° at the Pole.. Now, if Mr Scoresby had approached the Pole in a meridian passing through the New World, he would have encountered a cold of 24° in the latitude of 60°; and in the parallel of 78° this cold would have increased to 4°, as deduced from the formula. If we then subtract from this an anomaly calculated after Mr Scoresby’s ingenious process, we shall find that the: Polar temperature computed in this way is many degrees below the sero of Fah- renheit’s scale. Or, to state the argument more popularly, since the cold at the Pole is 10°, as inferred from observations made in the mé/dest meridian, it must fall greatly below this, and even below zero, if inferred from observations made in the coldest meridian. ‘The winds which blow from the continent of Greenland,—from the northern extremities of America,— and from the frozen coast of Siberia, must produce at the North Pole an influence which is scarcely felt in the Spitzber- gen seas. From all these considerations, we are entitled to infer that the formula, which represents the actual temperatures with such accuracy from the Equator, and through all the varieties of climate in the Temperate Zone, even to the parallel of 78°, where the fixed ‘ice acts with its full influence, is not likely to fail in its accuracy when extended to its limit; and, therefore, that the temperature of the Pole itself is not far from 0° of Fahrenheit,* " As this reasoning is founded on ‘the assumption that the Pole is the Mean Temperature of the Globe. , 309 The Meteorological observations which have beew recently made in Lancaster Sound by Captain Parry, confirm in avery remarkable degree the general formula, and the opinions re- specting Polar temperature, which I have endeavoured to es- tablish in the preceding pages.* Instead of giving too great -a degree of cold to the Arctic latitudes, as every person sup- posed the formula to have done, it errs on the opposite side, and ascribes to the parallel of '74}° a temperature of about 6°, whereas Captain Parry found it to beso low as 1°.33. This intrepid and skilful navigator, whose important disco- veries in the Arctic Regions do equal honour to the heroism of the men under his command, and to the liberality of the . British Government, observed the temperature of the regions which he visited, with peculiar care, and by means of the finest instruments. The observations were made every two hours ; and as the expedition continued nearly twelve months in the parallel of 74° 45’, and in the meridian of 110°, we may con- sider the mean annual temperature of that point of the globe as established by means of above 4300 observations. The following abstract of this valuable Journal has been kindly communicated to me by Captain Parry, with the per- mission of the Lords of the Admiralty. “ ABSTRACT of the Hecua’s Meteorological Journal for Twelve Kalendar Months, during which Period she was within the Parallels of 14° and '75° of North Latitude. Mean Temperature of REMARKS. laa Air in Shade. « During the time that we Max. Min. Mean. were in Winter Harbour, it “ was always found that the 1819, Sept. +37° —1° +422°.54 thermometer on board stood Oct. +17.5—28 — 3.46 from 2° to 5° higher than the Nov. + 6 —47 —20.60 one on shore, from the Dee. + 6 —43 —21.79 warmth created by the fires, coldest point of the globe, the results given above will admit of considera- ble modification, if that supposition shall be found improbable, as will be shown in the subsequent part of this paper. * This part of the paper was read before the rg he Society on the 4th December 1820, 310 Dr Brewster’s Observations on the 1820, Jane — 2 —47 —30.09 &c. The minimum tempera- Feb. —17. —50 —32.19 ture for February was —50° Mar. + 6 —40 —18.10 onboard,but—55°ontheice, Apr. +32 —32 — 8.37 Onthe ice, 14th and 15th of May, +47 —4 +16.66 February, the thermometer June, +51 +28 +36 .24 was at —54° for seventeen July, +60 +82 442.41 hours. Augt. +45 +22 +32 .68 The mean annual tempe- — ature may be fairly consi- Annual Temperature, -+, 1°.33 dered as 1° or2° below zero.” The intense cold which is thus proved to exist in the lati- tude of 745°, indicates, when compared with that in 78° in the Spitzbergen Seas, a very singular state of the Isothermal lines'at the Pole itself. The thermometric curve of 17°, which rises in the meridian of Spitzbergen to the 78th degree of north latitude, descends in the meridian of Melville Island to the 65th degree, and unless we suppose that the climate of these regions is subject to no law, we are forced to conclude that the Pole of the globe is not the coldest point of the Arctic hemisphere, and that there are two points of greatest cold not many degrees from the pole, and in meridians nearly at right angles to that which passes through the west of Europe. 4 Observations are still wanting to determine the exact posi- tions of the Isothermal Poles ; "ia they appear to be situated in about 80° of N. Lat., and in 95° of East and 100° of West Long. ; the ened eke: one being nearly 5° to the N. of Graham Moore’s Bay in the Polar Sea; and the Asiatic one to the north of the Bay of Taimura, ‘near the North-East Cape. This view of the distribution of temperature within the Fri- gid Zone, suggests, or rather renders necessary, a New Law of the Progression of Climates. The gradation of heat on the Transatlantic Meridian is so essentially different from that in the west of Europe, that it is impossible to represent the two classes of phenomena by one Formula, in which the limiting. temperatures are found at the Equator and the Pole. No at- tempt, indeed, has been made to include them in the same law, and still less to refer them to a principle which embraces all intermediate meridians. t Mean Temperature of the Globe. = = = 311 As we are not acquainted with the cause of the anomalous distribution of heat in high latitudes, observation alone must guide us in determining the form of the Isothermal lines. From their general resemblance to the Isochromatic Curves, I tried to calculate the temperatures by the product of the sines of the distance of the place from the two Isothermal Poles ; but this law did not represent the facts, and I found that they might be more accurately expressed by the formula Mean Temp. = 82°.8 Sin. D. upon the supposition that the greatest cold is 0° of Fahren- heit, or Mean Temp. = 86°.3 Sin. D — 33° upon the more probable supposition, that the greatest cold is — $3° of Fahrenheit, 82°.8 being the mean temperature of the Equator in the warmest meridian, and D the distance of the place from the nearest Isothermal Pole.* By applying this last formula to the results obtained by Humboldt, and to the observations of Captain Scoresby and Captain Parry, we shall have the following observed and cal- culated temperatures. + Mean Temp. of Old World. Mean temp. of New World. Lat. Observ.. Calc. Difference. Observ. Cale. Difference. 30° 70°52 71°61 + 1°.09 66°.92 62°61 —4°.31 40 63.14 63.31 +0.17 54.50 51.97 —2.53 50 50.90 53.16 42.26 37.94 39.65 +1.71 60 40.64 41 55 + 0.91 23.72 26.02 +2.30 743 Captain. Parry, =" a 1.383 487 +3.06 73 17.00 19 66 +2.66 Captain Scoresby. * The distance D from the Isothermal Pole is in the coldest meridian D=80°— Lat.; and in the warmest meridian Cos. D=Cos. 10° X Sin. Lat. Tn all intermediate meridians we have Cos. D = pinmadh atl. and Tang. § =Cos. M. Tang. L, where M is the difference of longitude be- tween the place and the Pole, I. the co-latitude of the Isothermal Pole or 10°, and / the co-latitude of the place. + The calculation for the Old World is founded on the supposition that the meridian to which the mean results of Humboldt belong is at right angles to the cold meridian in 100° west longitude. The greater number - of places, however, ‘from which the mean was taken, are nearer the Asiatic ‘than the American Pole. Hence we see the reason why the differences are all positive. 312 Dr Brewster's Observations on the The differences in the fourth and seventh columns are far from being considerable; and when we reflect upon the uncer- tainty in the position of the poles, and the range of the annual temperature at any given place, the coincidence of the obsery- ed and calculated results is greater than could have been ex- pected. In the preceding comparison, the places to which the mean results belong, are supposed to be situated either in the warm. meridian which passes through the west of Europe, or in the cold meridian which passes through North America. In com- paring, however, the theory with observation, we shall proceed to put it to the severe test of contrasting it with observations made in intermediate meridians, both in the Old and the New World; and in this comparison we shall begin with Oe Asia- tic Pole, and suppose it to have a temperature of — 34°, and to be placed in 80° N. Lat. and 95° of East Long. teat Greenwich. Pepa Distance from the | Mean Temperature. Asiatic Pole. Observed. Calculated. Difference. Enontekies, ~~ 20° 39’ 31°.03* — 26°.93 — 4°.10 Uleo, = 23 16 33 .08 30 .59 — 2.49 Umeo, ~ iu SOO 33 .26 33.11 —0.15 St Petersburg, 27 11 38 .84 35 .92 — 2.92 Stockholm, 29 44 42 .30 39 .30 — 3.00 Moscow, 2 29 55 43 .16 39.54 —3.62 Warsaw, = 36 06 48 .56 47 85 —1.21 Astracan, - 37 25 49 .08 48.94 —O.14 . Vienna, y 40 37 51.76 ° 52.68 +0.92 Pekin, : 40 56 54.86 . 53.04 — 1.82 Nangasaki, 4; 9 aT 60 .80 61 .58 + 0.78 Seringapatam, 68 04 77 00+ 76.55 ~—0.45 Columbo, - 73 12 79 .50 79 .12 — 0.38 From these differences, which are almost all negative, it ap- pears that we have assumed too great a degree of cold for the Asiatic Pole. If we make it 0° of Fahrenheit, we obtain the following results : * Reduced to the levik of the sea by Humboldt’s rule. + The mean temperature in 1814 was 78°.25, and in 1816, 75°75. No correction is applied for its elevation above the sea. Mean Temperature of the Globe. 313 Mean Temperature. fast Observed. Calculated. _ Difference. Enontekies, - $1°.03 29.20 — 1.83 Uleo, Lataei oR 32.71 — 0.37 Umeo, 33 .26 35.12 + 1.86 St Petersburg, 38 84 37.83 — 1.01 Stockholm, = 42.30 41.07 — 1.93 Moscow, cit AAG ee 41.30 — 1.86 _ Warsaw, = 48.56 | 48.79 + 0,23 Astracan, — - 49 .08 50.31 _ + 1.23 Vienna,.. .- 51.76 53.90 4+ 2.14 Pekin,. . 54 .86 — 64,25 — 0.61 Nangasaki, 60 .80 62.44 + 1.64 Seringapatam, 77 .00 76.81 — 0.19 _ Columbo, - 79 .50 79.26 — 0.24 ‘The differences in this Table (amounting at an average to 1°45) are far within the limits of the errors of observation ; but being negative in general, they may be reduced still farther to an average of 1°, by supposing the Asiatic Pole to have the ‘temperature of + 1° of Fahrenheit, which is 43° warmer than ' the Transatlantic Pole. ‘The formula in this case becomes | ‘T = 81.8° Sin. D +. 19, from which we obtain the following results : Mean Temperature. Observed. Calculated. Difference. Enontekies 31°.03 29.85 —1,18 Uleo, a 33 08 33.31 4. 0.23 ' Umeo, - 83.26 35.70 + 2.44 St Petersburg, 38 .84 38.87 | — 0.47 Steckholm, . 42.30 41.57 — 0.73 Moscow, = 43.16 41.80 — 1.36 Warsaw, ‘ A8 .56 49.20 + 0.64 Astracan, ~ 49 .08 50.70 + 1.62 Vienna, . «+ 51 -76 54.25 + 2.49, Pekin, « 54.86 54.59 — 0.27 Nangasaki, - 60.80 62.69 + 1.89 Seringapatam, 77 00 - 76.92 — 0.08. Columbo, - 79 .50 : 79.88 ms':17 314 Dr Brewster’s Observations on the In comparing the theory with observations made round the Transatlantic Pole, the results are equally satisfactory. The third column of the following table i is calculated from the for- mula T = (86°.3 sin D) — $}°, and the Pole is supposed to be situated in 80° N. Lat. and 100° West Long.* and to have a temperature of — 33°. Distance from | Mean Temperature. American Pole. Observed. Calculated. Difference. Melville Island, - 5°15’ 1°33 4°39 +4 3°.06 Upernavick, - 1215 16.84 14.81 — 1.53 Omenak, : 13 58 16.60 £17.83 +0 .42 Godhavn, - 17 08 22 .04 21.92 —0 12° Godthaab, - 20 19 26 07 26.46 + 0.39 ‘Fort Churchhill, - 2058 25.34 27.388 42.04 Julianzshaab, - 2425 380.33 32.17 +1 .84 Eyafiord, = 24 08 32.16 31.78 —0.38 Nain, . - - 25 16 30.03+ 33.34 +3.31 Okkak, < - 24 47 31.00 32.68 +41.68 Quebec, - - - 3444 41.90 45.67 43.97 Cambridge, - 39 04 50 -36 50.89 +40.53 New York, - 39 53 53 .78 51 .84 —1 .94 Philadelphia, “ 41 08 53 .42 53.27 —0.15 Williamsburg, . 43 40 53.10 56 09 —2.01 Orotava, - - 60 00 70.11 71-24 41.138 Eqvaron, | ¥ jong. 95 80 00 81.50 1 i ee pune In the reasoning from which Humboldt estimates the mean temperature of the Equator, he appears to me to have taken for granted a very material fact. Having found a coincidence between the mean temperature of equinoctial America and equi- noctial Asia, he concludes that the-mean temperature of the Equator is 81°.5, and is uniform in every point of that great * If we suppose that the observations in West Greenland, and those about Hudson’s Bay and Labrador, are best fitted to give the position of the Pole, it isobvious, that it should be removed a little from the former, and brought nearer the latter, so as to be placed a degree or so farther south. This change would also produce a greater coincidence with Captain na" s observations. + For 1779—80. See Phil. Trans. { Ibid. Ib. Mean Temperature of the Globe? 315 - circle ; but as these are the very regions under the line where the temperature should be the same, in consequence of being similarly situated with regard to Canada.and Siberia, no con- - clusion can be drawn until a similar temperature has been found on the African coasts of Benin and Loango. The heat under the Equator being thus supposed to be uniform, Hum- boldt felt himself entitled to conclude, that the colds of Canada and Siberia did not extend their influence to the equatorial plains,* and that between the tropics, the Isothermal lines are parallel to the equinoctial. The theory which I have explained above, requires a diffe- rent distribution of heat at the Equator. The mawimum mean temperature of that circle should be 82°.8 in Africa, in order to give 81°.5 as the equinoctial temperature in America and Asia; and the difference of these values, or 1°-3, must be re- garded as a measure of the influence which the colds of Canada and Siberia extend to the equatorial plains. Nor is this a mere theoretical result. I consider it as fairly deducible from facts furnished by Humboldt himself; and this distinguished travel- ler seems to have drawn from these facts the same conclusion, before he had deduced the uniformity of the equatorial tem- perature from a comparison of Asiatic and Aierican oheeha- tions. In his Political Essay on New Spain, he makes the follow- ing remarks: ‘ On the eastern coast of New Spain, the great heats are occasionally interrupted by strata of cold air, brought by the winds from Hudson’s Bay towards the parallels of the Havannah and Vera Cruz. These impetuous winds’ blow from October to March ; they are announced by the extraor- dinary manner in which they disturb the regular. recurrence of the small atmospherical tides, or horary variations of the baro- meter, and they frequently cool the air to such a degree, that at Havannah, the centigrade thermometer descends to 32° of Fahr., and at Vera Cruz to 60.8 Fahr.—a prodigious fall for countries in the torrid zone.”—vol. i. p. 65, Eng. edit.‘ The great breadth of the New Continent,—the prowimity of Canada, —the winds which blow from the north, &c. give the equinoc- tial regions of Mexico and the island of Cuba a particular cha- * Edinburgh Philosophical Journal, vol. iii. p. 263: 316 Dr ‘Brewster's Observations on the racter. One would:say, that in these regions the teimpetate zone,—the zone of variable climates,—increases towards the south, and passes'the tropic of Cancer,” &c.—vol. ii. p. 410. “On the east coast of Mexico,” he elsewhere remarks, “ the north winds cool the air, so that the thermometer falls to 62°.6 Fahr. ; ‘and at the end of the month of February, I have seen it remain for whole days under 69°.8 ; while, during the same period; the air being calm, at Acapulco, it is between 82°.4 and. 86°.. The latitude of Acapulco (16° 50’) is 3° farther south than that of Vera Cruz; and the high Cordilleras of Mexico shelter it from the currents of cold air which rush in from Ca- nada upon the coast of Tabasco,” (Lat. 18°)—vol. ii. p. 148.* From these quotations, it appears, that the cold winds from Hudson’s Bay produce a very striking effect upon the climate even of the tropical regions. Rising in the parallel of 60°, and - sweeping over the whole continent of North America, through an extent of 2600 miles, they retain their gelid influence even in the latitude of 18°. Can we suppose, then, that such winds as these cease all at once to impart their cooling energies to more southern zones. Acting with such power in the parallel of 18°, will they not refresh the opposite shores of the Pacific Ocean, and temper even the burning heats of the equinoctial line ? Whatever law of progression we may adopt to represent the ~ decreasing influence of these northern currents, in their passage towards the line, there is none which allows them :the influence described by Humboldt‘on the coast of Tabasco, that es not extend that mfinence to the Equator itself. : Although die bectading views, respecting the distribution of heat within the Polar Circle, make the temperature much lower than had previously been supposed, yet when taken in conjunc- tion with the results of the expedition under Captain Parry, they rather encourage the hopes which have been so gaan! entertained, of reaching the Pole itself. Upon. the supposition that there are two Isothermal centres in 80° of latitude, and that their temperature is—3}° of Fah- renheit, the mean temperature of the pole of the globe will be about 11°, incomparably warmer than the regions in which * See-also vol. i, p. 75. Mean Temperature of the Globe. 317 Captain Parry spent the winter. If an expedition, therefore, were to set out for Spitzbergen, and remain there for one or more seasons, till an opening should be found through the icy barrier which stretches from that island to the Greenland coast, there is every reason to believe that it would ultimately succeed. If the Pole is placed in an open sea, the difficulty of reach- ing it entirely ceases ; and if it forms part of a frozen conti- nent, those intrepid individuals who sustained the rigorous cold of Lancaster Sound, could experience no hardship under a com- paratively milder climate. Hitherto we have supposed the two Isothermal Poles to have the same temperature, and to be situated on nearly opposite meridians ; but this supposition is not rendered necessary by any of the phenomena, and we may obtain a better expression of the temperatures, by placing the Poles at different distances from the Equator, and ascribing to them different intensities. The existence of a cold and a warm meridian, is a proof that there are causes which powerfully influence the annual tempe- rature, independent of the position of the earth’s axis with re- spect to the sun ; so that the effects which they produce can have no symmetrical relation to the pole either in position or intensity. The two northern Poles of the tornauisinl magnet, for exam- ple, are situated, the one 4° and the other 20° from the Pole, and they have neither equal intensities, nor opposite positions. Imperfect as the analogy is between the Isothermal and the Magnetic centres, it is yet too important to be passed over with- out notice. Their local coincidence is sufficiently remarkable, and it would be to overstep the limits of philosophical caution, to maintain that they have no other connection but that of ac- cidental locality. The revolution of the two magnetic foci round the pole, the one in 1740 years, and the other in 860, has been recently deduced by Hansteen from numerous obser- vations, and if we had as many measures of the mean tempe- rature, as we have of the variation of the needle, we might de- termine whether the Isothermal Poles were fixed or moveable. - The idea of such a motion suggests an explanation of some of the most remarkable revolutions on the surface of the globe. There is no fact in the Natural History of the Earth better ascertained, than that the climate of the west of Europe was NEW SERIES, VOL. LV. NO. 11. APRIL 1831, x 318. Dr Brewster's Observations on the much colder in ancient than in modern times. When we learn that the T'yber was often frozen ;—that snow lay at Rome for forty days ;—that grapes would not ripen: to the north of the Cevennes ;—-that the Euxine Sea was frozen over every winter in the time of Ovid ;—and that the ice of the Rhine and the Rhone sustained loaded waggons ;—we cannot ascribe the amelioration of such climates to the influence of agricultural ene ‘The cold meridian which. now passes through Canadas and Siberia, may then have passed through Italy ;.and if we trans- fer the present mean temperatures of these cold regions, to the corresponding parallels in Europe, we shall obtain a climate agreeing in a singular manner with that which is described in ancient authors. ; It is not, however, in the altered condition of our atmosphere merely, that we are to seek for proofs of a periodical rotation of climate. |The impressions of the plants of warm countries, and the fossil remains of land and sea animals, which could exist only under the genial mfluence of the Temperate Zone, are found dispersed ‘over the frozen ‘regions of Eastern Asia ; and there is scarcely a spot on the solid covering of the globe, that does not contain indications of a revolution im its animal: and vegetable productions. . This interchange of the productions of opposite climates, has been ascribed to. some sudden alteration in the obliquity of the Ecliptic, and even to a violent displacement of the Earth’s axis ; but astronomy rejects such explanations, as irreconcile- able with the present. condition of the system, and as incom- patible with the stability of the laws by which it is governed. Having thus endeavoured to establish a new law of the dis- tribution of heat.over the surface of the globe, it might be no uninteresting inquiry to investigate the causes which have mo- dified, in so remarkable a manner, the regular influence of the solar rays. The subject, however, is too comprehensive, and too hypothetical, to be discussed at present. How far the ge- neral form and position of the continents and seas of the north- ern hemisphere may disturb the natural parallelism of the iso- ~ thermal lines to the Equator ?To what extent the current through Behring’s Strait, transporting the waters of warmer ! _ Mean Temperature of the Globe. 319 climates across the Polar seas, may produce a warn meridian in the direction of its motion, and throw the coldest points of the globe to a distance from the pole >—Whether or not the magnetic, or galvanic, or chemical. poles of the: globe, (as the important discoveries of M. Oersted entitle us to: call them), may have their operations accompanied with the production of cold, one of the most ordinary effects of chemical action ?—Or whether the great metallic mass which crosses the globe, and on which its magnetic phenomena have been supposed to de- pend, may not occasion a greater radiation of heat from those points where it developes. its. magnetic: influence >—are a few points, which we may attempt to discuss, when the progress of science has accumulated. a greater number of facts, and made us better acquainted with the superficial condition, as well as the internal organization, of the globe. Note A.—As Mr Playfair’s observations were made in Wind- mill Street and Buccleuch Place, where the thermometer must have been influenced by the heat. reflected from the opposite sides of these streets, I consider the mean of his annual tem- peratures, viz. 47°.8, as erring in. excess, and have therefore preferred 46°.23, the result of Messrs Miller and Adie’s ob- servations. _ This opinion respecting the temperature of Edinburgh is strongly confirmed: by the following valuable and accurate ob- servations, made and communicated to me by my friend Mr James Jardine. — \ - Temperature of the Crawley Spring, situated 564 feet above the level of the sea. 1811, 30th January; 46°.5 Fahrenheit. . 21st. March, 46 .0 18th April, 46 .2 19th August; 46.7 . 46.35 Add for 334 feet above Mer- chant Court, 1.00 Mean Temp. at Edinburgh, , 41.35 520 Mr Potter on the Reflective Powers Temperature of the Black Spring, situated 882 feet ‘above the level of the sea. 1815, 12th January, 44°.8 Fahrenheit. 1811, 31st January, 45 .0 1818, 4th February, 44 .6 1811, 18th April, 44.8 1810, 17th September, 45 .0 : 1819, 8th October, 44.8 1810, 31st December, 45 .0 Mean, 44.86. Add for 652 feet above Mer- chant Court, 1 .95 46 .81 Mean Temperature at Edin- burgh from Black Spring, 46 .81 Mean Temperature at Edin- burgh from Crawley Spring 47 .35 General Mean ‘Temperature of Springs at Edinburgh, 47 .08 Art. X.—Ezaperiments relating to the Reflective Powers of Crown, Plate, and Flint Glass, with theoretical considera- tions.—(Continued from last Number, p. 67.) By R. Potter, Esq. Junior, Associate of the Society of Arts for Scotland. Communicated by the Author. Havixe proceeded so far in determining the reflective powers of metals and solid transparent bodies, it becomes desirable to consult in the original Bouguer’s Traité dOptique, a work now become very scarce in this country, and also Mr Her- schel’s Treatise on Light, in the Encyclopedia Metropolitana, which latter not being sold separate, I have found almost equal difficulty in getting a sight of it as of the former. Bouguer was the first who undertook any photometrical in- vestigations with success ; he examined almost every subject to 6 of Crown, Plate, and Flint-Glass. 321 which photometry could be applied, and the address with which he adapted his instruments to their particular objects must always rank him amongst the most ingenious of experi- menters; but the very great variety of subjects he undertook must be considered a misfortune, in preventing him paying that critical attention to the more important ones which would have contributed more to his lasting fame. In his examination of the reflective powers of the transparent bodies, glass and wa- ter, the greatest fault in the photometer he used appears to have been that it gave him considerably less light as reflected at small angles of incidence than it ought to have done, where- as the error in the plan I have described lies the other way, until the extraneous light is measured and allowed for. But I was particularly surprised to find that the numbers in his tables of the reflections by glass and water were not the actual results of experiments, but calculated from assumed formula,— a fact of which few would be aware from the manner in which they are generally given in English works. He says that he determined the reflections at some incidence, and particularly at the very high ones and the very low ones, and then sought a formula to calculate the numbers in the tables. He says he verified the numbers for water at several different incidences, and found them sufficiently near, but he does not speak so clearly respecting those for glass; but it will be seen on com- parison that the numbers in his table do not differ more at the higher incidences from mine for both surfaces, than we should have expected from the insufficiency of his photometer for ob- taining very critical results. ‘The formula he used for water was this, A + B 2° +C 2° where z is the versed sine of inci- dence, counted from the perpendicular, (with him it was the co-versed sine as he counted the angle of incidence from the surface) and that for glass was A+B 2° —C =‘, where 2 is the same variable as in the other. The art of polishing specula was not sufficiently advanced in his day to give him a fair chance of discovering, in his in- vestigations with them, the law of the variation of the reflec- tive power ; and though he says he used a mirror of a “ trés beau poli,” yet, from his other remarks, there is no doubt that its polish was quite insufficient for the experiment. In mer- 322 Mr Potter on the Reflective Powers cury he would not have the same difficulty ; and, accordingly, it was to me highly amusing and instructive to learn from his own words the pains it cost him to deceive himself when his experiments must have shown him that the real law for metals was different essentially from that for transparent bodies. In my former paper on the reflection by metals, I expressed an opinion that mercury, being in the fluid state, might follow a different law from the solid metals; but after reading Bouguer’s reasons to himself, for not always finding the result as he wished, I have now no doubt how the fact stands. But his success in deceiving himself was more complete than after a long lapse of eighty to ninety years it was with myself, when, unexpectedly, I again fell upon the same thing. On repetition of the experiments, I awoke to the full value of a discovery perhaps of equal importance in physical optics with any of late date, and of which I have just reason to be highly proud, and this on several accounts; first, that I believe it is the ex- periment to settle the question of the rival theories on the na- ture of light, as to whether it is an emitted matter, or only consists of undulations or vibrations in a subtile ether. I think those candid mathematicians who have adopted the un- dulatory theory will acknowledge that the essential difference in the laws for metal and glass cannot be accounted for on any supposed. differences in the state of the assumed ether in those bodies. The refractive power, on their hypothesis, having no other foundation than the metaphysical principle of Mauper- tuis, must exist wherever the ether should be of different den- sity; but reflection, on the same hypothesis, has no other basis ; and hence reflection and refraction must exist together; and it has accordingly been the custom to deduce the supposed re- fractive powers of opaque bodies from their reflective proper- ties. But if it can be proved, strictly speaking, that the me- tals have no refractive power, and that reflection does take place in bodies which do not possess it,;—what becomes of the undulatory theory >We must acknowledge that it is not founded on the law of nature. But we have no need to take more than a single view of the laws for metals and transparent bodies to convince ourselves of the essential differences be- tween them ; and the latter being known to be possessed of re- of Crown, Plate, and Flint-Glass. SRP. fractive power, we seek in vain for any analogous expression: in the laws for metals to that in theirs. On the Newtonian theory, where the effects are referred to the action of attrac-. tive and repulsive forces.on dynamical applications, this dif- ference in the laws is no more than we should expect from the different. physical characters of the bodies, and is capable of being accounted for in as satisfactory a manner as any other Optical phenomenon. TI have reason also to be proud, that the fact does not appear to have been at all anticipated by the most eminent mathematicians of the present day; and I re- spectfully regard it as a mark of unprejudiced philosophical _ spirit'in Dr Brewster, to admit into his scientific journal a paper which went to controvert the opinions to which the most enlinent opticians were committed in print. The undaulatory theory has been spiritedly supported by some of the first French mathematicians, and they have brought to the inquiry the highest analytical talent. Now, if the formule which they iiite’ deduced from the undulatory hypothesis are found to give results at variance with observed phenomena, we are justly entitled to draw an argument from ' it, against the hypothesis from which they emanated, as being also at variance with fact. And if the:consequences of the un- dulatory theory, as they have been developed in the hands of Young, Poisson, Fresnel, Arago, and Biot, do not accord with experiments, to whom must the defence of the theory be » intrusted ? M. Poisson and Dr Young, from considerations on this theory, have given for the intensity of the reflected pencil, at a perpendicular incidence, the following expression Y f —_— 2 . . . . . G rE i ) where yw’ is the refractive index of the reflecting body, and » that of the medium which is in contact with it. Then, for the reflection at the first surface of flint glass in air, we have Gat) = 491, or of every 100 rays inci- dent 4.91, whereas experiment gives only 3.61 as reflected, in crown glass refractive index 1.524, we should have .0431, or of every 100—4.31, and experiment gives only 3.45 as really reflected, in plate glass, refractive index 1.517, we should have 0421, or of every 100 rays 4.21 reflected, and it is only 324 Mr Potter on the Reflective Powers in fact 3.38, these differences amounting to } of the whole re- flection are sufficient to set at rest all opinion as to the suffi- ciency of the formula. M. Fresnel’s formula ‘which, when sin? (¢ — 7?) t being the angle of incidence and 7# that of adapted to light in its natural state, becomes if tan? (¢ — a tan? (i + refraction, as also quantities quite at variance with experi- ment, as will be seen by only considering, that, at the greatest incidence possible, the squaresof the sine and tangent of (i—7,) become equal to the squares of the sine and tangent of (+7) and the formula becomes 3 (1 + 1) or unity, so that the whole light incident ought then to be reflected, whilst it has been known since Bouguer’s time that no known substance re- flects at any incidence, all the light falling upon it, but always, even at the most favourable one, absorbs or transmits a very large proportion, and never less than about 4 in any substance - yet tried. At a perpendicular incidence the formula falls ‘into the one of M. Poisson’s above, and so is there liable to the same objections. Thus we see that the deductions of the ablest advocates of the undulatory theory stand opposed, not to my experiments only, but to those of the father of photo- metry, made near a century ago; and when we read in the works of Fresnel and Young, the unbecoming expressions they have used towards Newton, we must not blame them too harshly, but remember in charity, that, when so large a beam _ was in their own eye, they could not possibly see clearly to draw out the mote from Newton’s. Mr Herschel, who has said of the undulatory theory, that “ It is in fact, in all its applications and details, one succession of felicities, insomuch that we may almost be induced to say, if it be not true, it de- serves to be so;” and-has since spoken even more decidedly, will now see that the Newtonian theory has a claim to an apo- logy from him. At the close of my last paper, I said that I intended to try again a few of the measurements of the reflections for both surfaces of glass, as there was more irregularity amongst those there given than was admissible, to enable us to form a pretty certain judgment, as to whether the reflections were equal, if of Crown, Plate, and Flint-Glass. (ae the rays were incident indifferently on the surface from the den- ser or the rarer medium. I have since obtained the following, : 2 a a goon op 3 gts 8 3 Ue a S > © 838 e 4he 8 Oe ae ae i! eee oie wos 8 See eo enn See Bee oS. cS RES ie? rm 48 7.85 8.82 4.03 — 4.37 25 4.62 80 946 71 8.75 457 418 1 458 .25- 483 50 12.16 1.11 11.05 665 440 =. 4,94 .29 5.23 70 27.54 .55 26.99 16.01 10.98 + 15.06 31 15.87 which are still more irregular than were to be wished ; but we must remember that the error in the whole light for both sur- faces is concentrated in that for the second surface, and we may consider fairly, that they go to prove the correctness of the law I have before enunciated. - To trace whether the values of the constantsin the formula Cc r+-b—x had any connection with, and dependence on, their known phy- sical properties, it was required to determine still the refractive indices and specific heats in the specimens made use of in the experiments. The results in the table below were obtained by many repeated trials, both in the refractive powers and the capacities for heat, and I believe they may be considered very near the truth. Though some of the specific heats differ in some degree from what are found in books on chemistry, I have so far proved these numbers, by making the trials in the reverse ways, that I believe I have got them very near correct. I make the specific heat of flint glass much less than Mr Dal- ton has done; and some of the older chemical writers have made it even half as much again asI do. It is an experiment that requires some precautions ; and I may some time give to the public the means I have taken to secure correct results. The refractive indices of the crown and plate glass I deter- mined with Dr Wollaston’s instrument, but was obliged to for solid, singly refracting, transparent bodies y = a + —— 326 Mr Potter on the Reflective Powers polish a small prism of the flint. It will be seen that I formed an erroneous guess at the refractive power of the plate glass, in supposing it of that sort which has higher refractive power than crown. Specific Refractive Specific heat Reflect. at | gravity. index. _ for equal bulk. highest incid. Flint glass, . 3.225 1.570... 43. APD)... Plate, 2.511 1.517 39 "F426 Do. 2.425 1.501 mt a Crown, — 2.541 - 1.524 188). ORR FSS Speculum metal, 8.900 “GT ae Steel, (hard) 7.800 68° “Ser I remarked at the close of my last, that transparent bodies like metals only reflected a portion of the light incident on their surface at the highest possible incidence, and in that on the reflective powers of metals, I had traced a remarkable connection between the light that steel and speculum metal . reflect, and their capacities for heat. It is highly desirable to ascertain if the law will hold with other metals, and T think silver, and perhaps some others, may, by those who work in them as trades, be brought to a sufficient polish for determin- ing the reflective power at the highest incidence, which is all that is required to prove the question ; but it holds so far, as we see, in solid transparent bodies, when the reflection is un- influenced by any perpendicular velocity in the rays, that I venture to propose the following law: That in all solid bo- dies capable of receiving a truly smooth (or polished) surface, the reflective power, when uninfluenced by any perpendicular velocity of the rays of light, is a function of their capacity for heat. It is probable that a similar law will be found im li- quids, but it is clear that we must not expect to compare them at once with-solids, whose particles are in so different a state of aggregation. 2 If we take the formula for glass ya ay we may put it under this form, y =4@ +—>2; : Lay = r+ sing of Crown, Plate, and Flint-Glass. 327 ; c2 (r+ sin 2) cos? i+ a+ Bebb sind) by putting for r—wz its value —— Fame if we put y = the quantity of light which passes the surfaces and enters the glass by virtue of the particular direction of the motion of the rays to rah surface, or between the limits y = a + sepend ya + 5 ©. which is equivalent to removing the origin of the co-ordinates in the figure of the hyperbola to the rf 2 point in the axis of y, whose ordinate is equal to a +5 and counting y’ negative to y, and if we put y” equal to the quan- tity reflected, which depends on the different values which the variables in the formula may receive, we shall always have See a, ae ae geae ae e e(r—2 te Aer Rat: Male’ “5 maa ets fiw it i *) ce oie: Oe? S and ys y": b(r+ ‘ae ¢fb—e2 °° b(r + sing) & >: cos? é ? b(r +siné) or the portion of light which enters the glass is to the portion which is reflected on this considera- tion, as the square of the perpendicular velocity of the ray, to é multiplied into the radius plus the sine of incidence; and this is conformable to what Sir Isaac Newton has deduced ‘for the action of the attractive force which produces the effect called in this case refraction. The formula for stdherp may be put under this form, y = @’ (r—2) ¢b=0(— a mm a) + U' by putting a’ for — aandb for b + ar where, a being a negative quantity, a’ becomes posi- tive, we see that the variable part in this formula is the reciprocal of the principal variable part in that for glass, and so any ana- logy as to refractive power in metals must be imaginary. Upon what we may learn when the second surfaces of transparent bodies have been examined photometrically at incidences pro- ducing total reflection, it is almost too much to hazard a sur- mise, but the similarity of their effect in what is denominated circular polarization to that called elliptical polarization in metals, would encourage the idea, that we may some day be able to unravel the secret of the mode of action of the more subtile properties of matter, and arrive at satisfactory 328 Mr Potter on the Reflective Powers, &c. conclusions on points which we can now hardly safely under- take. : . Respecting the values of c? and 8, it is clear that they must be such as to agree with the phenomena at the perpendicular, as well as at the highest, incidence. In the aes case we have the intensity of the reflected ray y = @ + a and in the latter y= a@ + zt now there are an infinity of numbers which will give the same value for y in the latter; but being re- “quired to agree at the sametime with the former, this takes away theindetermination when we know the value of a. When a re- mains indeterminate, we can only give the quantities such values as will agree best with the experiments, until further investi- gation shall enable us to deduce them from other considera- tions. If farther research shall confirm the law that the value of ha depends on the chemical property of the capacity of — bodies for heat, we shall be one step nearer, and perhaps ex- periments on the high refracting glasses may give a clue to the whole phenomena of the perpendicular reflection. The undulationists will soon find, no doubt, that they have only to allow for the effect which I attribute to the capacity for heat, to bring their formula for the intensity of the reflec- ted pencils at the perpendicular and the highest incidence, pretty near to the correct quantities; but they will find rather more exercise for their ingenuity to accommodate them to the intermediate incidences. Mr Forbes on Barometric Instruments, &c. 329 Arr. X1.—Memoir on Barometric Instruments acting by Com- pression, considered particularly in their application to the. Measurement of Heights; including some new Trigono- metrical Determinations. By James D. Forzes, Esq. F. R. S. Ed. Communicated by the Author. Part II.—Practical Inquiries connected with the Measure- ment of Heights. As the basis of most of the following deductions of absolute height, and as affording an estimate of the degree of confidence to be placed in the trigonometrical operations, the results of which are to be recorded in the following pages, I deem it proper to commence with some account of the determination of the height of Colinton House above the mean level of the sea. Most of these deductions, and many of the comparisons of the barometric results for which they were made, were com- pleted some years since; and I only discovered extremely re- cently that I might, as far as the immediate result was con- cerned, have dispensed with some of the most laborious of these operations. Through the kindness of Mr Jardine, civil | engineer, whose elaborately accurate results by actual level- ling of the heights of many positions of interest, (and most of which are yet unpublished,) must be of the highest importance to those engaged in such inquiries, I have obtained the ele- -vation of a point not far distant from Colinton House, and easily connected with it by actual levelling. ‘Ihe near ap- ‘proximation of my results to those obtained by Mr Jardine in this laborious, but accurate manner, and freed too from all the uncertainties of terrestrial refraction, must, as will presently -be shown, form the best guarantee for the extreme precision of the base line which I employed, and which formed the foun- dation of all my determinations of heights in the Pentland range. This, and other verifications to be pointed out in the course of the present paper, and which effectually exclude all idea of ac- cidental coincidence, enable me to speak with some confidence 330 Mr Forbes on Barometric Instruments ng on the use of the theodolite, and to express my opinion, that instruments of even small size, made according to. the present _ very improved state of the art of dividing, are capable, under judicious use, of giving results of far greater delicacy than is commonly imagined. The theodolite, for the most part, has either been used as little better than a toy, the unpractised or negligent observer reading off the indications in a much looser way than even the graduation directly afforded, or omitting the precautions of reversing the instrument and comparing the verniers,—or else it has been treated like the circle of a fixed observatory ; made unwieldy in dimensions, and its indications examined and reduced with the aid of every optical resource, and every mathematical refinement. I am confirmed by Pro- fessor Leslie * in saying, that under the one form it has been used: much too little and too carelessly ; and under the other, a prodigality of analytical refinements have been lavished upon it, which the precision of the most splendid instruments in ex-. istence could scarcely warrant. Were ordinary and small sur- veys carried on more extensively by the use of the theodolite, and less by the chain, far more precision would be attaimed.: it is always desirable to abridge the sources of multiplied error on the field, even at the expence of more complex labour in the closet. And where larger triangulations are to be made, considering the accumulation of sources of error which may be fallen into in the measurement of a long base line, where the ground is not highly favourable, it is perhaps. best for those unfurnished with costly and laborious apparatus for the mea- surement of such bases, to content themselves with one repeat- edly verified and of moderate length, from which, with every attention to accuracy, a secondary base may. be obtained by triangulation, fromthe extremities of which the great angles may be taken. From experience, I am disposed. to: recom- mend this where the ground is not particularly favourable ; in this other case, I shall also have an example to — of an op- posite mode of procedure. The instrument with which the following trigon ocala observations were entirely made is a theodolite by Troughton. It is a portable one of the usual dimensions, the circle being * Geometry. Notes 4th edit. Pp. 427, 448. ee ee a acling by compression. 331 five inches in diameter, and divided on silver by double verniers \ tosingleminutes. Butalthough the division is not carried far- ther, with such an excess of accuracy (as it: may fairly be termed,) is this graduation performed, that those accustomed to ocular subdivision will readily carry it down to 30”, and even 15”; which last I have constantly been in the habit of doing in all my surveys. When due use is made of this pri- vilege, and combined with the full application of the double verniers, and the reversing of the telescope, (a sharp achroma- tic) in the Y’s, which give fowr readings for every angle in azimuth, we are prepared to elicit results of very considerable delicacy.’ The particular instrument in question is certainly one of uncommon merit, and the same minuteness. could not be expected from all of its size, even by the same celebrated maker. Mr Troughton considered it one of superior excel- lence. My trigonometrical deductions have been confined to the counties of Edinburgh and Kincardine; but those with the sympiesometer have been extended to many other parts of Scotland, from which a selection will be given in due order. § 1. Trigonometrical Determinations near Edinburgh. ’ The short base line already alluded to was measured near Colinton House with a steel chain by Troughton, and was. found to be 1334.1 feet ih length, by a mean of two measure- ments which differed only by a small fraction. Nearly paral- lel to this was the principal base from which the observations were to be made, terminating in two commanding points, one on-the top of Colinton House, the other being the summit of Craig-Lockhart Hill, a picturesque eminence about three miles west of Edinburgh. ‘The horizontal length of this base line, deduced from the former, was 4393.6 feet. To find the height of that extremity which terminated on the roof of Colinton House above the: medium level of the sea, a tri-. angle was formed by measuring two angles which bounded this known side, and which were directed to a cliff at the western extremity of Inchkeith, an island in the Frith of Forth. This triangle required every precaution and. atten- tion to minutiz which the instrument was capable of ren- 332 Mr Forbes on Barometric Instruments dering sensible, as it lay rather obliquely to the base line, and one of the computed sides-was no less than 50413 feet, or al- most ten miles in length. J had also to struggle against the uncertainties of terrestrial refraction, as the angle on which the final height was to depend was one of depression. ‘To elimi- nate as much as possible errors of this description, six angles of depression were taken on different days, at different times of the day, and in different states of the tide; to each of these proper corrections were applied, the mean refraction being taken at one-tenth of the included are, or 50”, and the correction for curvature amounting to 60.3 feet ; the average of all the results being taken, and the local reductions made, the height of the lowest door step of Colinton House proved to be 389.6 feet above the mean level of the sea. i Since I did not possess then, as now, accurate verifications of this deduction, I proceeded to confirm it by deducing the height of Arthur’s Seat above Colinton House, the altitude of which being accurately known, that of the latter might be in- ferred. Abandoning, therefore, the base of 4893.6 feet, I de- duced a new one from the fundamental measured base. The configuration of the ground was'such as to induce me to extend an extremely oblique triangle to Arthur's Seat, so oblique that I should not have given much weight to the observation itself, had it not proved eminently confirmatory of the results already obtained. Here the angle was one of elevation, not of depres- sion, and it measurement, like the last, was frequently repeat- ed. The length of the secondary base in this case was 3419.3 feet, and the distance of Arthur’s Seat from its western extre- mity 22097 feet. The deduced height of Arthur's Seat above the door-step, was 429.6 feet, and the former, being by the re- sult of a double levelling of my friend Mr Jardine, 822 feet above the mean level of the sea, we have 392.4 feet for the height of Colinton House, differing only two feet and eight- tenths from that by direct observation ; a surprising coinci- dence, considering the nature of the operations. This confir-. mation applied, of course, only to the trigonometrieal part of the operation, and, as the fundamental base was the same in both, could furnish no criterion of the accuracy of the lineal measure of length. Of this I have now to furnish the confir- mation afforded by Mr Jardine’s level already alluded to, and acting by compression. Lot 9M 333 which I have-only had an opportunity of reducing by a con- necting operation of levelling within a few days. I had the satisfaction of finding the height of the point already discussed, to come out by this process equal to 385.5 feet, (the uncertain« ty of the precise point to which Mr Jardine levelled may be stated safely at a foot,) which certainly approximates as nearly to my original result of 389.6 feet, derived from a triangle with one side of ten miles long, as could have been anticipated. The base from Colinton House to Craig-Lockhart being thus authenticated, the results deduced from it on the neighbouring eminences are next to be concisely noticed. In the first place, by numerous observations of the elevation of Craig-Lockhart top, its height above the eye on Colinton House was deter- mined as follows : By altitudes, - 140.0 feet. By depressions, 143.6 Mean, 141.8 By other observations, 142.4 wisce 142.1 By my mean of Colinton House, or 391 feet \ : Beaght of the eye on the roof, 437.6 579.7 By the deduction from Mr Jardine’s observation, it would be 55 feet lower, or 574. feet. Three principal points were observed from the extremities of this base, (which extremities we shall denote by the letters—C, for Colinton, and L, for Craig-Lockhart,) forming part of the Pentland range, bearmg the names of Kirkyetton, Allermuir, and Warklaw Hills, which we shall denote by their initial letters. The following angles were ascertained : K LC 76°.57'.48" Alt. 4°.23'37" LOCK. 83°.16'.52” Alt. 5°. 7.30” ALC 62 .22.15 Alt. 4.99.87 .§ LCA 97.39.22 Alt. 5 .56.45 WLC16 .25.24 Alt. 3.1.7 LEW 1155.37.33 Alt.3 .4.28 The two first triangles being solved, we find LK=12911 CK = 12663, L A = 12748 C A=11395 , NEW SERIES, VOL. IV. NO. 11. APRIL 1831. Y 334° Mr Forbes.on Barometric Instrwments And the ptopee corrections being made for refraction and. cur vature, we deduce for the heights above the sea, KirKYETTON. | ALLERMUIR. By Craig-Lockhart, 1576.3 By Craig-Lockhart, 1622.9 By Colinton, 1571.7 By Colinton, 1620.5 Monin 1574 Mean, "1621. 7 Or taking Mr Jardine’s level for Colinton, 1569.5 and 1616. Q Kirkyetton was measured by General Roy half a century ‘ago; * but though provided with so good an instrument as a quadrant by Sisson, of twelve inches radius, he does not seem to have obtained such precise results as I have been able to do with Mr Troughton’s theodolite, of which the circle has a ra- dius of only 21 inches. He places the Calton Hill at 344 feet above Leith Pier, and Arthur’s Seat at 803 ; whence, from the height of the latter given above, we may compute his estimate of the Calton Hill above the medium level of the sea to be 363 feet, certainly considerably too great, as the foundation of the column of the present astronomical circle is only 346 feet. His result for Kirkyetton is 1544 feet above Leith Pier, or 1563 above the medium level of the sea, which comes within six feet of my measure, (taking Mr Jardine’s constant of the height of Colinton) ; but, from the general agreement of my measures with the results of levelling, I confess I am disposed to give the latter the preference. It is only extremely recently that Mr Jardine has furnished me with a direct determination, by levelling, of the height of Allermuir, which he found to be 1615.96 feet above the me- dium level of the sea, differing only three inches from that just given, his determination of the level near Colinton being adop- ted. With regard to the triangulation of Warklaw, still greater pains were taken, as it was meant to be in turn a new station. All the three angles of this triangle were measured, the last being from the summit. ) WLC = 16°.25..24’ L.C W = 155 .357.33 CW Baas. «tek ad Sym, 179 .59.34 * Philosophical Transactions at large, for 1777, p. 718. ».. acting by compression. ae . Leaving an error of less than 9” to be added to each angle. From thence the following were computed : CW = 8987.2 feet. L W = 13115.0 feet. The altitude of Warklaw, as deduced by Craig- ~ Lockhart, - - - 920.3 i By Colinton, 919.7 Mean, 920.0 Or with Mr Jardine’s constant, 914.5 feet. One principal object in making Warklaw a new station was to obtain an accurate result of the height of the Bonally Reser- voir, on which I had made many barometric experiments, and the precise determination of which was also of great consequence to some delicate researches in theoretical meteorology, yet un- published. Here again I was anticipated by the more trust- worthy, and most indefatigable operations of levelling, con- ducted by my friend Mr Jardine ; but it was only to afford - another near coincidence in the results of our two methods. The following angles were taken, denoting by B, the chimney top of the water-keeper’s house at Bonally Reservoir. BCW=31°.21'.52" Alt-3°.50'.30" CW B=87°.13'.34” Alt. 2°.8'.56” . Whence we have B C — 10225 feet, B W = 5328 feet. And, applying the equations for refraction and curvature, we find, Height of B above C 686.2 feet, above W. 200.3 feet. Reduction to level of sea, 437.6 929.0 1123.8 1120.3 Mean, 1122.9 Chimney top above embankment, 19.5 Embankment above the sea, - 1102.5 With Mr Jardine’s constant, 1097. By a mean of two detailed systems of levelling which agreed with surprising precision, Mr Jardine found this point to be 336 Mr Forbes on Barometric Instruments 1095.45 feet above the sea; agreeing within hog inches of my determination... Another, object of. the base line Cc w, was to approximate to the height of the Dalmahoy .hills, of which previous esti- mates seem,to have been considerably erroneous. In Boué’s Essai Geologique sur (Ecosse, the West and East Dalmahoy’s ¢ aré respectively stated at 680 and 660 feet ; in Knox’s County Map at 866 and 826. My observations were, from more than one circumstance, not so. perfectly trustworthy as the others I have cited. I shall therefore not enter into particulars, but only state, that every correction was applied with perfect pre- cision, and that I have good reason to believe that the probable errors do not exceed five or six feet. West Dalmahoy Hill 849 feet.—East ditto, 796 feet. With Mr Jardine’s constant 844 791 § 2. Determinations of Heights near Edinburgh with the Sympiesometer. A complete detail of all the observations I possess would form a lengthened, and I believe fatiguing work.: Of the great number which I have made, I shall select those localities which have had their altitudes most frequently measured, or such as are intrinsically interesting, and, instead of giving the details of the individual readings, the principles which have guided the selection of the most unexceptionable, the observations of the barometer. for the hourly variation, and all the reductions and logarithmic computations which have been founded on these, I shall digest the most material data and final deduc- tions into small tables, which may convey all the most impor- tant information at a glance. - I beg to premise a few words upon the mode of computation of the heights employed. Mr Adie’s fathom, or logarithmic scale of the instrument, has been almost universally employed, _ giving the approximate height by simple subtraction. The sympiesometer is peculiarly well fitted to have a scale of this sort, because the height of the oil in the tube cannot be ob- served with the precision of mercury in the barometer, and, therefore, the accuracy of a vernier would be superfluous. In my instrument, single fathoms of altitude could be observed “acting by compression. — 337 and in some cases half of these by estimation. Under such circumstances, any refinements in the correction of the approxi- mate height would be but a waste of time, independent of the inherent defects of the instrument, such as I have already shown them to be. Since the instrument professes to require no correction for the attached thermometer, (except that per- formed by the sliding scale,) such as the barometer stands in need of, the only correction worth mentioning ‘is that for the temperature of the air. Now, until the correction for the ef- fect of humidity is brought more generally into use than has yet been done, even with the aid of the elegant researches of Anderson and the convenient tables of Galbraith; any re- finement in this correction were quite uncalled for even with delicate instruments. ‘The expansion of perfectly dry air is exactly .00208 parts of its volume at 32° for 1° Fahr. But in moist air this goes so high as .0025, or .0026. We need not wonder, therefore, that barometric formule differ materi- ally where the effect of humidity is overlooked. Laplace em- ployed ,3, for 1° Centigrade, which corresponds to .0022 for 1° Fahr., and was probably selected for convenience of appli- cation. General Roy fixed upon .00243, as is generally stated ; but Pictet carried it so high as .00251.* Under this diver- sity, I have always employed a rule of extreme simplicity, and for the heights to which it has generally been employed abun- dantly accurate, even for instruments of greater precision than the sympiesometer. I have added ;4, of the approximate height for every 4° that the mean of the detached thermome- ters exceeded 32°. Nothing can be simpler than the correction under this form. As I am anxious to give some specific idea of the ordinary limits of error of the sympiesometer, I should wish to separate ‘them in some measure from the preponderating error of gra- duation in the instruments, as explained in the former part of this memoir. For that purpose, I shall give along with each result, its deviation from the mean of the results, not from the real or geometric height, in hundredth parts of that mean. We shall thus have a pretty correct view of the results of ob- servations on a variety of heights, which, unless reduced to a * See Ramond sur la formule Barometrique de la Mecanique Celeste. 338 Mr Forbes on Barometric Instruments common standard, would not be directly comparable. As by far the most numerous observations on one point which I pos- sess are those of the height of the Bonally Reservoir, I shall commence with them. Having been already detailed, I shall merely assemble the results in the manner I have just: propos- ed, J shall arrange them in two departments, of hot and cold ‘weather, in order to show that, as the adequacy of the barome- ‘tric corrections for temperature is. well established, in its present form, the instrument contains proper sources of error, which are brought out by extremes of temperature. Bonatty ResErvorr.—Height by levelling, 686 feet. WINTER SERIES. ¢ No. of Error Exp. Date. Barom. Att. Ther. readings Height from below. below. above. above. deduced = mean. Remarks. 1829. 1. Dec. 31. 30.30 57 30 2 679 ft +.05 Snow. 1830. 2, Jan.1. 30.27 55 2 2 642 —.01 — do. 3. Jan. 9. 29.53 58 36 1 618 —.05 4. Jan. 23. 29.63 42 30 1 639 —.02 5. Feb. 12. 29.49 59 39 2 945 —.01 6. Mar. 13. 29.50 (64 42 1 618 — .05 7. Apr. 17. 28.64 64 47 1 381 —.10 Highly un- favourable. Mean, 29.62 58.4 35.6 1.4% 631.7 041 Meanexclud- 9979 67,5 343 1.5 649.2 ing Exp. 7. SuMMER SERIEs. 1829. 1. May 20. 29.81 63 54 4 671 + .03 2. May 26, 3021 62 53 4 696 + .07 3. May 30. 29.89. 65 55 7 634 — .02 Rather diffict. 4. July 6. 29.32 67 58 2 698 + .08 Brisk wind. 1830. 5. June 5. 29.37 63 53 2 675 +04 | 6. June 26. 29.02 64 61 4 676 + 04 7. July 24. 29.23 68 67 1) 678 _ + .04% Verydifficult. 8. July29. 29.55 74 |. 62 8 587 —.10. Fog Mean. 29.55 65.7 57.9 5.2 664.4 054 tie Rap. 6. 25% 64.6 57.3. 4.9 675.4 6 ~ ie © © aeting by compression. f 339 . These results are not a little important. In order to show the conditions under which the instrument was placed, and in ‘order to afford data for the computation of its native irregu- -larities, I have given in the three first columns the pressure by «the sympiesometer at Colinton, or at the base of the 686 feet, ‘and the temperature by which it was affected at the two sta- -tions. We see the wide range of temperature to which it was “exposed in winter, amounting at a mean to almost 24°, the lower station being an inhabited room. The fourth column shows the number of observations at the upper station, which the circumstances of the case required, to give an estimate of ‘the time and attention necessary to observation in the open air. Here we have a striking difference between the summer and winter series, the former amounting at a mean to 5.2 ob- servations, which, taking the intervals at 5’, gives nearly half an hour of patient attention as requisite, the latter only to 1.4. -It must, however, be observed, that where only one or two observations were made, the stay I made was generally not less than 15’ or 20’, and it was only being otherwise oc- cupied which prevented me from making more during the time ; as in cold or dull weather the same incessant attention is not necessary as in hot weather to catch the passing affections, provided sufficient time be allowed, which is almost al ways con- siderable. The next column contains the heights deduced ; and the one following, their deviations from the general mean of the whole observations, or 649 feet, in decimal parts. The very striking result is the great and constant error of the win- ter eleevagiens. whilst the summer ones, instead of erring be- yond the geometrical height in excess, as the others do in defect, still come short of it by a few feet; and in spite of all the dif- ficulties and uncertainties which have been fully shown to ac. company observations in warm weather, are by far more accu- rate than those made easily and with small chance of error in the use of the instrument at a colder season; the source of _ this error is to be sought in the range of temperature. ‘The mean deviation is taken without regard to sign. Now, it is obvious from these observations that the summer series, so nearly answering to the required condition, (the geometric height,) the mean results of the data which affect, the perfor- «l a 340 Mr Forbes on Barometric Instruments mance of the sympiesometer, are nearly those under which it was formed to act with accuracy, or, in other words, under which it was originally graduated. But farther than this, I | am prepared to show by an analytical process, which will here- after bé-given, that in order to satisfy the mean results of these two series, the neutral points of the instrument must be 30.03 inches, and 60.°4 Fahr., that is, the scale of pressure was gra- duated at a temperature of 60.4, the scale of temperature, un- der a pressure of 30.03 inches, by the mean result of pressures of the instrument, which, in order to accommodate it to that corrected for the index error, may be increased about 0.1. This is a very interesting result, even supposing it not strictly applicable to ald other cases; more especially from the nature of the upper station, which, being rather in a basin on the north slope of a range, the barometer is known by experience to stand higher than on insulated summits,* and therefore the height comes out smaller than it ought to do. This is illus- trated by the following observations : ALLERMuvIR HILL. Height above Sympiesometer at Colinton House, by levelling, 1206.5 feet; by Trigonometry, 1206.7 feet. No. Error Exp. Date. Barom. At. Ther. obs. Height from Remarks. below below. above. ab. deduc. mean. 1829. 1, May 20, 29.81 63 56 4 1286 + 05 Brisk E. wind. . July 6, 29.32 67 52 2 1246 + 02 Brisk W. wind. 1830. 8. June 9, 29.74 61 50 4 1150 —0O7 Wind N.E. moderate. . July 15, 29.00 66 58 4 1265 +08 5S. W. violent clouds and showers: iN) = 5. Aug. 3, 29-13 67 57 5 I196 — 03. Mean, 29.40 64.8 54.6 3.8 1229 -040 Now, as I mentioned in § 1 of the last part of this memoir, that, the neutral points being given, the true pressure would be found by increasing its deviation from the standard pres- sure, whether + or —, by y4, part for every 5° that the ther- * Ramond, Mémoires sur la formule Barometrique de la Mecanique Celeste, p. 49. ' acting by compression. “341 mometer was below the standard temperature, or, diminishing ‘it by the same quantity if above that point, could we once ob- tain the neutral point accurately, the correction of any other observation for this source of error would be easily perform- -ed. By comparing this series, however, with the summer one of the Bonally Pond, it is pretty obvious even to the eye that the same neutral points cannot satisfy both. I shall quote some other observations which may be classified with the last, and which will enable us to extend this generalization. KirkyEtTtTron Hitt. By Trigonometry, 1169 feet above Colinton House. No. ’ Exp. Date. Barom. Att. Ther. obs. Height Remarks. below. below. above. ab. deduc. 1. May7, 29.32 64 51 6. 1156 - Bright sun. 1830. | 2. July 15, 29.00 66 56 4 1208 Violent S. W. wind and showers. Caretaw HI. By Knox’s County Map, 1080 feet above Colinton House. No. Exp. Date. Barom. Att. Ther. obs... Height. Remarks. below. below. above. ab. 1829. a3 May 20, 29.81 63 54 4 1052 Wind E. brisk. 2. July 6, 29.32 67 55 4 1087 Wind W. brisk. Warkviaw Hitt. By Trigonometry, 505 feet above Colinton House. No. Error Exp. Date. Barom. Att. Ther. obs. Height. from Remarks. below. below. above. ab. mean. 1829. 1. May 26, 30.21 62 53 3 520 + .03 Wind brisk. 2. Dec. 31, 30.30 57 31 2 517 +.02 Snow. 1830. $. May7, 29.16 65 55 3 534 +.06 HighS,wind 4. June 23, 29.22 62 3 467 —.08 Imperfect. Bright sun 5. July 22, 29.28 62 64 4 487 =~ 03. Sultry.. Wind -W., moderate, Ce ere eee 29.63 63.0 50.7 3.0 505 342 Mr Forbes on Barometric Instruments By taking the whole of the observations on Allermuir, Kirk- yetton, and Capelaw, on the one hand, and the whole of those ‘on Warklaw on the other, and subjecting the means to analy- sis, we may show that their conditions are satisfied, by assign- ing the values of 29.93 inches of pressure, and 44°.6 of tem- perature for the neutral points. The former may be consider- ed asa very striking coincidence, and that the latter should be so much lower than that deduced from the Bonally obser- vations, is certainly not wonderful, both on the account already alluded to, and when we consider that in the one case the pairs ‘of results differed much in temperature, and very little in pres- ture, and, in the other, the circumstances were precisely reversed. Those, too, who are aware of the mode of eliminating two un- known quantities, must also know that there are two scales of corresponding values of the two quantities sought, the respec- tive variations of which nearly satisfy the conditions of the prob- lem, whilst the determination of the precise value is one of great delicacy, and requires a large series of observations. Had we possessed appropriate corresponding winter observations on these insulated heights, we should probably have attained a truer value of the neutral points. I shall confine myself to the results already detailed, which are the fullest I can offer on the Pentland range; nor can I permit myself to dwell on the nature of particular results, or to quote single observations on elevations, even though intrinsically interesting, as I have already given in last number, a pretty full analysis of the Bo- nally series, with illustrations of particular errors to be guarded against. The want, too, of precise geometrical determinations, has prevented my extending the list, as I have not found the results in Knox’s County Map, however interesting in a gene- ral point of view, sufficiently precise for such delicate compa- risons ; and, in particular, I suspect that he has overrated the heights of the southern Pentland range, viz. Turnhouse Hill, Carnethy, East Black Hill, East and West Kip,—on which, however, my observations are too meagre to stand alone. § 3. Trigonometrical Determinations in Kincardineshire. Of no range of hills, perhaps, in Britain has a more vague estimate been formed with regard to height, than the north- * acting by compression. 343 east district of the Grampians. Many-of their summits bore the character of being much higher than they had any title to, such as Mount Battock, formerly considered to be 3465 feet above the sea, * (which, by its irregular number, gave some ground of confidence in its accuracy,) but proved by the mea- surements of Dr Skene Keith to be no more than 2600. Of other elevations extending into the high land of Aberdeen- shire, very little has till lately been known, and that alone by the aid of the barometer; the same observer has proved that there are eminences in that remote district, capable of at least throwing a doubt upon the claim of Ben-Nevis to be the high- est land in Britain. I was induced by an extremely favourably position for measuring a base line, to determine the height of an interest- ing pass named from two heaps of stones which mark its sum- mit, the Cairn o’ Mount, which is the only communication for carriages across this mountain range for a great district in that direction. It so happens that the great road between Stonehaven and Brechin, in traversing that extensive flat, known under the — provincial name of the “ How of the Mearns,” extends for a long distance in an almost mathematically straight line. Along a portion of it, in September 1829, I measured a base with the greatest care twice over. By the first, it proved to be 2663.07 feet; by the second, 2662.77. The mean, or 2662.93 feet, was employed in the following deductions. _'There were two points to which my observations were princi- pally directed, the Cairn Hill already mentioned, which form- * See Col. Imrie’s paper on the Geology of the Eastern Grampians ; Edinburgh Transactions, vol. vi. Had this diligent observer been in the habit of using the barometer in his geological excursions, even in the roughest way, he could not have failed of detecting the enormous errors of this assigned elevation. It has been a principal object in the inquiries which form the substance of this memoir, to endeavour to furnish geolo- gists and trayellers in general with an instrument at once commodiously portable, prompt in its action, and accurate in its results. Without some- thing more effective in these respects than any barometer we at present possess, it is vain to look for:any great extension of this interesting class of facts. I trust before this memoir is concluded, to be able to offer some de- finite proofs of advancement towards this great object. 344 Mr Forbes on’ Barometric Instruments ed the sky line of the northern horizon occupied by the pri- mitive range of Grampians; the other was the summit of a flat- topped chain bounding the southern side of the great flat of Kincardineshire, composed of red sandstone, and: virtually forming a continuation of ‘the Sidlaw Hills, but having the particular appellation of Garvock. The Cairn Hill is the on- ly one which I have yet compared with the sympiesometer. Denoting the east and west extremities of the base line by KE. and W., the summit of the western heap of stones already mentioned by C, and the top of Garvock by G, the follow. ing angles were measured. CEW = 105.° 2’ 45” CWE = 68. 30.30 WC = 22907 feet EC = 22071 feet. Alt. 3° 5! 15” Alt. 3°11 37” The correction for refraction being taken at ,,th of the in- cluded are amounts to 22” ; which being aseplinl yaa will result. Height of C above W. end, 1231.3 Above cast end, 1227.2 Correction for curvature, + 12.5 + 11.6 Reduction for each station ; to acommonone, which }— 19.5 _ — 15.0 we shall call (F.) Height of the Cairnabove (F) 1224.8 1223.8 Mean of both 1224.0 Estimated height of (F) above the mean | level of the sea, i : 294.0 © ; Height of the Cairn Hill, TEA, Fs By a similar operation, Garvock was found to be ‘709.1 feet above station (F,) or 1003 above the mean level of the sea. The absolute height of station (F) was derived from four observations with the sympiesometer, which not being all made under favourable circumstances, must be taken as mere- ly an estimate. ‘The distance was from twelve to fifteen miles acting by compression. 345 from the sea shore, and only the two first observations had the benefit of being repeated on areturn to the first station; the hourly variations in the other cases being taken from previous and succeeding observations, they have therefore only half the wae given to them that they would otherwise have had. Date. Height. Divisors. _ Value. ~ 1829. Sept. 21, 297 feet. 2 594 - 1830. Apr. 27, 267 wee Rae 1880. Apr. 22, 351 1 351 1830. May 4, 283 1 283 6 ) 1762 Estimated height, 294 feet. On no subject have such gross errors remained uncontra- dicted as that of levels; the elevations which we have now de- termined at 1518, 1003 and 294 feet, have usually passed for 2000, 900, and about 100 feet. § 4. Selection of Measurements by the Sympiesometer in Kin- cardineshire and other parts of Scotland. I. Kincardineshire.—The only observations which I shall quote here at present, beside those just given for the deter- mination of the absolute height of the station: (F'), which was the second floor of Fettercairn House, are a comparison of the height of the Cairn Hill by this method, with the geometrical ' one. 1829, September 22d.—Height of West Cairn above the second floor of Fettercairn House, or station (F'), by going and returning observations with the sympiesometer, 1240 feet. By trigonometry, 1224feet. Error = + ae ~ Pressure below 29.18. Att. ther. 63. m4 Att. ther. upper station, 49.6. I have already given the general results of the measurement of the: height of station (F) above the sea, and I shail not enter here mto particulars, nor into those of observations made with the sympiesometer in some neighbouring counties, of which, in the great paucity of known facts connected with this “eurious subject, I do not at present possess means of verification. 346 | Mr Forbes on Barometric Instruments II. Peebles-shire-—Although nearly destitute of geometrical — determinations of the heights now to be noticed, yet some of these are in sufficient number to be instructively comparable with one another, or sufficiently interesting to render even am approximate determination not without value.- The fundamen- ~ tal station, which I shall call (H,) in the parish of Eddlestone, was no less than thirteen miles distant in a direct line from Colinton House, and two ranges of hills intervened. They had the benefit, however, of nearly contemporaneous observa- tions with the barometer at the other station. The following are four determinations : | | ! Date. (H) above Colinton. Deviat. from mean. 1829. June 4, 280 feet. —.02 1829. June 22, 307 +-.07 1829. Oct. 9, 294 4.02 1829. Oct. 15, 263 —0O7. »~ Mean, 286 045 (H) above the sea 701 feet. In Knox’s County Map of Edinburgh, Eddlestone village (with which station (H) is nearly on a level,) is marked 750 feet above the sea; but I have good reason for believing that estimate to be too great, especially from Mr Telford’s level of the height of Peebles Bridge, 1 in the course of a survey for a projected canal. The first subsidiary point I shall notice was under cover, and therefore the instrument was not so liable as usual to the fluctuations of external temperature. I shall denominate it by the letter (G). . June 1829. (G) above (H). Att. Ther. No. of obs. Var. from Exp. Barom. below. Below. Above. above. Height. mean. 1 29.20 58 59 2 «204 +.02-— "2. 29,64 57 . 62 2 187 —.06 3 29.72 66 63 1 175 —A2- 4 29.10 5Y «64 5 235.1.) gee 5 29.23 59 61 , 4 194 —.02 Mean, 2.8 199 .08 Above the sea, 900 feet. acting by compression. 347 - The next station was a step higher; we shall denominate it by (S) and we place beside it a table containing two values of the height of a considerable piece of water, cea Athel- stane Loch, or West Loch. (S) above (H.) June 1829. West Loch above (H.) Deviation ; Exp. Height. from mean. _ Exp. Height. 1 305 ft. —.02 1 293 2 304 —.02 2 278 3 326 4+.05 —_— 4 308 | —.01 Mean, 285 oo Above the sea, 986 feet.. ~ Mean, 211 025 Above the sea, 1012 feet. Mr Knox places West Loch 1012 feet above the sea; but, by reducing his height of (H) to my estimate, it will be brought even lower than that I have just given, and the same applies to the reduction of his other levels in this dis- trict. For example, he places Jeffries’ Cross, which forms the summit of Dundroich, or the Druids Hill, at 2044 feet above the mean level of the sea. By very careful observations with the sympiesometer on the 6th of June 1829, I made the highest summit, or Jeffries’ Cross, 1269 feet above (H,) and the western summit 1112 feet, or 1970, and 1813 - above the sea. The former, when increased 50 feet for the difference of Mr Knox’s level, near (H,) and mine, gives a pretty near approximation. Dundroich is generally stated at 2100 feet, but, until better observations be obtained, I would substitute 1970. It is hardly necessary to observe, that, in order to obtain the results with Mr Jardine’s level of Colinton House, we must deduct 5.5 feet from the preceding heights above the sea. : IL. Stirlingshire—The following measurement of the height of Benlomond is so instructive that I shall give it in detail. Aug. 10, 1830.—Weather very fine; sultry; bright sun- shine, with passing clouds; almost calm even at the summit. 348° Mr Forbes 6x Barometric Instruments ‘The following observations were made at the level of Loch Lomond at Rowardinnan. The’ instrument was sheltered both by brushwood and an umbrella from direct radiation. ” Att. ‘Ther. 12°0 29.675 = 191 Fath. 63.8. - F 29.42 = 226 683A... 10 29.40 = 229. 62.8 — 20’ .29.31 = 242 61.4" 30° 29.3825 = 239 G1. 33’ 29.34 = 238 © 62.3 389 29390 = 245 - 62.4” 43 = 290.31 = 242 62.4 Thus, after three quarters of an hour of observation, some doubt yet remained as to the actual pressure indicated at the level of the loch: but even were a traveller’s patience un- limited, his time is not; I was, therefore, obliged to set out, and selected 242 fathoms as the probable true pressure by the logarithmic scale. bite On the summit of Ben Lomond circumstances were more favourable. | . . Att. Ther. Att. There 3h 45° 6901 Fath. 48.5 4°10 «700 F. = 50.5 50’ 105 50.0 25° 696 ~—- B04 4 0 695 56.2 30 696 50.4 5 "700 56.? Rowardinnan, 3 feet above the lake. Gt 157 us rere 99.29 = 246 F. 629 o7 29.44 = 2241 606 93° 29.44 — 2242 60.4 26° 29.46 = 220 59.7 35 29.46 = 2201 «5.8 There can be very little doubt that one, if not both the series of observations of Rowardinnan failed of giving the true pressure, especially as I had reason to believe that the barome- ter was sinking during the day, and not rising, as above indi- cated. Be this as 1t may, we can only take the observations acting by compression. 349 as they’stand before us. By reducing them in the manner already explained, we shall find the height to be 2965 feet. The geometrical height by the trigonometrical survey is 3177 feet above the level of the sea, or 3145 above that of the lake. This result, therefore, errs 180 feet an defect. IV. Argyleshire—The last example which I shall select at present, is a determination of the point in the great military road through Glencroe, known under the name of “ Rest and be thankful,” from an inscription left there by the soldiers who made the road, and which forms its summit level. The height of this interesting pass may very probably be known, but I am not in possession of any previous determination of it. Observations with the sympiesometer were made, August 17, 1830, at Cairndow, on the bank of Loch Fyne, and at Tarbet, on Loch Lomond, both being reduced to the mean level of the sea; the variation of pressure was obtained for the interval about the middle of which the instrument had been observed at the summit level of the military road; and the proper reductions being made, the height of the latter proved to be 874 feet. § 5. Onthe Mean Error of Measuremenis by the Sympiesometer. In several of the preceding observations, I have given the errors in decimal parts of the mean results, wishing to sepa- rate in some measure the predominant error arising from the graduation of the instrument. It is clear, however, that by this method, especially where the variation of circumstances is considerable, we can arrive at no fair result, and that each ob- servation should be corrected for the known deviation of its conditions from the neutral points of the instrument ; the devi- ation of these from their means would then represent the real un- certainties of the measurement, freed from errors admitting of numerical estimation. We might, then, by the aid of the doc- trine of probabilities, compute the probable error attaching to a single observation, or to a series. In the present case, how-~ ever, such a result would be little worth the labour, unless it were desired to show the amelioration produced on the instru- ment by putting it under a new form. But upon this I am not yet prepared to enter. We may, however, remark, that in all such estimations there are two distinct classes of error, which it would require extensive series of observations satisfactorily to ‘ NEW SERIES, VOL. IV. NO. 11, APRIL 1831 Z 350 Mr Forbes on Barometric Instruments, &c. separate. One is a function of the height measured, the other is not. ‘The former is common to all species of barometric levelling, depending on the variable condition of the atmo- spheric strata ;—the latter is due to particular sources of error in the instrument, and may be as great (and is’ frequently " greater) in a very small elevation than in the highest. Hence we should do the instrument injustice by confining our expe- rimenits to a small scale. ‘The possible error might then amount to a large fraction of the result. It is to this object that all our labours to improve the instruments themselves are directed, whilst the determination and correction of those errors which (generally speaking) are deperident upon, or functions of, the height itself, is one of the most interesting problems to’ which the attention of philosophers has been’ directed ; and their researches upon this subject alone would have been sufficient to immortalize the names of Deluc and Faiesiopey 06> and Play- a and Laplace, and Ramond. § 6.-On the application of ithe Sympigaumeter to diate ob- servations, or continuous levelling. The very interesting results which we obtain from ideal sections of a district of country by barometric levelling, give us an estimate of their importance, equalled only by their rarity. The fine examples of Humboldt, executed in tropical regions, leave at a distance any thing we can hope to achieve im: the mutable atmosphere of our northern climate. The barometer is very seldom stationary, and almost as rarely are its varia- tions uniform, even for a few hours together. If, therefore, in travelling observations, we have no fixed register for com- parison, (and a register at any considerable distance from the point of observation will hardly answer our purpose,) we must laboriously discover by actual observations, at a moderate in- terval of time, the variation of ptesstre even several times a day. Now, to attain this object, i it is manifestly. of paramount importance that the action of the instrument shall be prompt, and true to the smallest fraction which it is capable of indicat- ing. In this respect, I found the sympiesometer extremely defective in Some pretty extended experiments which I made on this application of'it in August and September 1829. The period was certainly particularly unfortunate for such an essay, as it was exactly during the continuance of those memorable Mr Kupffer omthe, Temperature of Springs. 351 floods which Sir Thomas Lauder’s interesting work has ren- dered familiar, as far as Morayshire is regarded, but which also extended with great violence over the whole eastern dis- trict of Scotland. Under such circumstances, many of the most interesting periods of observation were irremediably de- stroyed by the rapid fluctuations of the barometer; but in some cases, even under every disadvantage, I obtained pretty accurate results. ._Throughout a journey of several hundred miles, the instrument was most sedulously observed; and, partly from inconsistencies of observation, partly from the want of ascertained elevations for comparison, even the most careful reduction of the whole of these observations has not furnished me with results so generally correct as to warrant ime in publishing them. Nor even under favourable circum- stances could I expect results worthy of great confidence, without having an instrument by which we might from a single hour’s observation obtain a very correct value for the actual change of pressure ; and this is so far from being the case with the sympiesometer, that it would be often difficult even to as- certain the direction of the variation. But I cannot close these remarks without bearing testimony to the portability of the instrument, which went through the journey just alluded to, embracing many of the middle and eastern counties of Scot- land, in an open gig, and during the most variable weather, without meeting with the slightest accident. Postscript. —Since the first portion of this paper was printed off, I have ascertained more precisely, by the aid of a spirit level, the height of the chimney top of the waterkeeper’s house at Bonally above the embankment, . which (not looking for so close 4 coincidence with the result by levelling) was roughly stated at 19.5 feet.in page 337. - I find it, however, to be 21.2 feet, which reduces the actual height with Mr Jardine’s constant to 1095.3 fect, agreeing within two inches of the result by levelling. Arr. XII. —Observations on the Temperature of Springs ‘made during a voyage to Mount Elbrouz in Caucasus. By _M. Kurrrrr, Member of the peasy. e of Sciences of St Petersburg. ‘Tnx following interesting annte forms the fifth section of M. Kupffer’s valuable aceount of the voyage to Mount Elbrouz, undertaken by command of the Emperor of Russia. The ge- “meral report on the voyage is drawn up by M. Kupffer, who 352 M. Kupffer on the. Temperature of Springs. has been so. kind as to communicate it to the Editor. The “aud sections will be published i im successive articles. “ In a former memoir, (See this Journal, No. iii. NowMibiany p- 134, and No. iv. p. 251,) I showed, from a great number of observations collected by different observers and by myself, that the distribution of heat in the interior of the globe, and at a small distance from its surface, was’ different from that which is observed at the surface, or rather in the air which surrounds it. I afterwards demonstrated that we might ex- press, by a very simple formula, the decrease of heat from the Equator to the Poles in the stratum of the terrestrial crust where the oscillations of temperature vanished,—a heat which is car- ried to the surface by springs of a nearly constant temperature. This formula has, I have since been informed, been given in the Mecanique Celeste, where Laplace says that it represents with sufficient accuracy the decrease of the mean temperature of the air from the Equator to the Poles. It is easy to convincé ourselves, that it expresses much better still the observations hitherto collected relative to the temperature of the ground. The facts which I have consigned in the memoir already quoted, were chiefly collected in the west, north, and east of Europe. Our journey to Caucasus gave me an opportunity of increasing the number of them, by observations collected in the south-east. I have at the same time been able to deter- mine more exactly. the decrease which the temperature of the ground experiences relative to its elevation, by observations made at points which differed greatly in level. I shall first give an exposition of these observations, and shall then connect them with those made in other parts of Europe; and I shall endeavour to unite these facts under a single point of view. All our observations were made with thermometers carefully calibred after the method explained by M. Bessel in his col- lection of astronomical observations. We always chose copious springs, and we almost constantly observed several springs at the same point, and sometimes at two epochs sufficiently dis- tant to ascertain their variations of temperature. The tempe- rature of wells was observed only to show that their tempera- ture depends on particular circumstances, and is often inde- pendent of that of the ground. Observations of this kind can- not be employed in the determination of the temperature of the ground. The following are the observations themselves : M. Kupffer on the Temperature of Springs. 353 1. St Petersburg. Lat. 59° 563’, long. 27° 591’ east of Paris. —An abundant and slightly ferruginous spring at the village of Okhta, in the park of M. Koucheleff-Besborodko, in the months of May and June, in degrees of Reaumur, - 4°.9 2. Moscow. Lat. 55° 45’, long. 35° 17’, elevation 600 feet nearly.—Spring of Pakrovsky, a small village, 18 versts from Moscow, on the left of the road to St Petersburg, 10th Sep- tember, - - 5°.2 8. Sadonsk. Lat. 52° 20’, Nele. 36° 35°. —An abundant spring rising from a very porous calcareous rock, June, - 5°.9 4. Moskovskaia Krepost. Same latitude as Stavropol, and thirty versts to the west of it.—Several springs which rise from “a calcareous rock, the most ai of which and the coldest was at the end of June, - 8°.5 5. Stavropol. Lat. 45° 3/, long. 39° 393’, elevation 1800 feet nearly.—Several abundant springs had in August a tempera- ture of from 8°.8 to - - 8°.5 6. Taganrog, on the sea of Azoff. rad 4'7° 12’, long. 36° 37’. —Several very copious springs observed by M. Elsingk with a thermometer not verified, Bk 10° 7. Nicolaieff, a town situated very little above the Black Sea, and distant from it only seventy versts. Lat. 46° 58’, long. 29° 40/.—A spring at Spasky near the observatory, tempera- ture not constant, - - 9°.8 8. Hot Springs of the Caucasus. at 44° 2’, long. 40° 42’, elevation 1300 feet.—A very agli spring at the foot of Ma- chouca in August, - - 10°.6 9. Stone Bridge on the Malka. Lent, 48° 45’, elevation 2500 feet—Copious spring, but exposed to the sun, July, 8°.5 10. Three small apeitigs in a narrow close valley, between high mountains, at some distance from the stone bridge of Malka, where we were 5800 feet above the sea, 3°, 34°, and 4° 11. Jn our Camp on the Upper Malka, at the foot of El- brouz. Lat. approx. 431°, elevation 7'700.—A spring of sweet water on the banks of the Malka, - - 3°.3 A spring of acidulous water, . “ 3.5 12. On the Bermamac. Elevation obtained 7500 feet.—A small spring observed during rain, P atest 49.2 5 B54 M. Kupffer on the Temperature of Springs. The points 8 to 12 are situated under meridians very little different. At Sadonsk, No. 3, the temperature of a well was. found to be No. 2. At Jsvali, situated to the north of Voro- nege, in the parallel nearly of 52° 40’, the temperature of a well six metres deep was exactly the same. 'This temperature ought to be below the mean temperature of the country. The observations, No. 8, 9,10, 11, give us a new determi- nation of the decrease of the temperature of springs in a yerti- cal line.. The four points at which these observations have been collected, being little distant from each other, we have. only to compare the differences of their respective elevations. In this way we obtain the three following data: | Diff. of Temp. Brie Reaumur. Diff. of Level. No. 8 and 9 2.1 1,200 feet No. 8 and 10, 7.3 4,500. No. 8 and 1], y th Be 6,400 The two first data give a decrease of 1°, Reaumur in every 600 feet. The third differs too much from the two first to be admitted into the same calculation. We should observe that the springs, No. 8, 9, and 10, rise upon similar strata, that is upon a caleareous rock ; while No. 11 issues from a trachy~ tic soil. This last gives a decrease of 1° Reaum. for 877 feet. The mean of these numbers is 1° for 740 feet. The reduction of 1° for every 600 feet of height rests on too few observa- tions to be adopted finally ; but it is sufficiently exact for ob- servations at small altitudes. After making this reduction, we obtain the following results : : Temp. ground at Lat. Long. level of the sea. St Petersburg, = ary (SOBT. 28°, 0 _ 4°.9 Reaum.: Moscow, pics "ty 55.45 3517 ss Sire ‘Taganrog, - 45 3 3940 11.0 Stavropol, ‘ 4712 3937 10.0 Nicolaieff, ‘ 4658 2940 9.8 Hot springs. of Caucasus, 44 2 4042 12.7 Malka Bridge, - 43 45 12.7%. No. 10, - 7 12.7 to 13.7 Camp on Malka, 16.1 > M. Kupffer on the Temperature of Springs. 355 All these observations were collected in a season when the temperature of springs varied little from its mean value through... out the year. In the memoir already quoted, I have shown, that, by uniting the observations made under the same meri- dian, the decrease in the temperature of the ground, in virtue ¢ the latitude, i is very well represented by the formula a—b Sin2l = t, ) t being the temperature of the ground at twenty-five metres’ depth, (the point where it begins to become constant,) / the la- ‘titude of the place of observation, and a and 6 constants which must be determined by observation. We shall begin our calculations with the meridian of S¢ Petersburg ; but as we have made only two observations on this meridian, we shall use the observation at Cairo under the same meridian, where the temperature of the ground is 18°.0. In this way we have the three following equations: a — b Sin.’ (30° 3’) = 18°.0 a—b Sin? (4658) = 9.8 @ — 6 Sin’ (59 57) = 4.9 The combination of which, by the method of least squares, gives a = 24,40 b — 26,41 These values of a and 6, substituted in the preceding equa- tion, give the following values of ¢: St Petersburg, ¢= 4°.7 Cale. 4°.9 Obs. _ Nicolaieff, é—103 9.8 - Cairo, t= 17.8 18 .0 By combining the observations of Moscow, Taganrog, and Stavropol, we obtain in the same manner, , a = 24.20 b = 26.36 Whence we deduce the following results: _ Moscow, t=; 62 Cale. . 6°.2 Taganrog, ¢= 10.1 10.0 Stavropol, ¢= 11.0 11.0 356 M. Kupffer on the Temperature of Springs. The following table contains the values of a and 6 for six different meridians, the only ones from which I could iealeet a sufficient number of observations. : ' a b a—b Havanah, 84° 43’ W. of Paris, 240 33.7 — 9.7 Meridian of Paris, = 21.3 LOG 4 O.4 Upsal, 15° E. of Paris, . 24.4» 25.6 —12 Petersburg, 28° E. of Paris, 24,4 26.4. © .——2.0 Moscow, 35° KE. of Paris, 24.2 26.4 © -—— 2.2 Bogoslovsk, 60° E. of Paris, 22.9 QD AG These values of a and } enable us to calleglate the different points under the above meridians, where the temperature of the ground i is successively equal to 0°, 5°, 10°, &c. and the preced- ing formula gives Sint = o/*=£, or 0s 91—1—~-2. ot. The following table has been calculated by means of this formula. Temp. of Corresponding heat under the meridians of 1 ground. 85° W. 0° 15°, 30 35" 60 0 57°33 77°30’ | 74° 2 =—"73°13B. Ss 65° AB 5 4840 62 1 6031 59 1 5831 53 47 10 40 8 4720 4836 4737 4710 43814 15 31 7 3318 3718 3638 3611 3225 20 20 9 1427 2430 24 6 2830 1857 Hence we may easily draw upon any map lines through the points of equal temperature. In this way, we shall obtain curves which I have called Jsogeothermal lines, to distinguish them from the Isothermal lines, whose curvatures they in’ ge- neral follow, but from which they sometimes separate consi- derably at several points. In the north, for example, the Iso- geothermal lines are more distant from the Equator than the corresponding Isothermal lines, or rather, which is the same. thing, the temperature of the ground is higher in the north than that of the air. In the vicinity of the tropics, on the contrary, the mean temperature of the ground is lower than Adjudication of the Wollaston Medal. 357 that of the air, as the observations of MM. Humboldt, Buch, and others have decidedly proved. If we call the mean temperature of -a surface unequally heated, the sum of the mean temperature of all its points di- vided by this number, it is evident that the mean temperature of the surface of the ground in our globe cannot be different from that of the atmosphere which touches if ; but, neverthe- less, the distribution of the heat of the ground may, at a cer- tain depth, deviate considerably from that of the temperature of the air—the propagation of heat in a solid body, and a bad conductor, like the earth, not being submitted to the same laws as the propagation of heat in air, the theory of which has not yet been given. I abstain at present from any farther de- velopement of these ideas, which I shall ‘submit in another memoir to a new discussion and a more profound examination.” Art. XIII.—Observations on the recent adjudication of the Wollaston Medal to Mr Witu1sm Situ for his Geologi- cal discoveries. Ix the account given in the Spectator, February 26, 1831, of the proceedings at the anniversary meeting of the Geological Society, held on the 18th February, the First award of the Wollaston Medal is announced in the following terms :— «“ The late Dr Wollaston having bequeathed to the Geolo- gical Society L. 1000, the interest to be employed annually in recompensing or encouraging geological inquiries, and the Council having directed a medal to be struck, bearing the im- press of Dr Wollaston, the first of these, together with a sum of money, has been adjudicated to Mr W. Smith. Before the delivery of this medal, the President gave a chronological aecount of the discoveries of Mr W. Smith, by which he jus- tified the terms of the following award, viz. * That the first — Wollaston Medal be given to Mr W. Smith, in consideration of his being a great original discoverer in English Geology, and especially for his having been the first to discover and to teach the identification of sdvate, and their MPR ta of imbedded fossils.” The scientific readers of this Journal may remember that 358 Adjudication of the Wollaston Medal. when the Royal Society of London adjudged, for the, first time, the two Royal Medals to Mr Dalton and Mr Ivory, we expressed. our doubts of the propriety of the principle which the society seemed. to have adopted, We were of opinion that the Royal Medals were founded for the purpose of pro- moting new discoveries, and not of rewarding old ones, and we ventured to mention the names of several distinguished indi- viduals who would be entitled to receive the Royal Medals in future years if the society continued to act upon the principle with which they set out, (See this Journal, No. xii. p. 369, April 1827.) Whether the Royal Society were influenced by our statement, or discovered of their own accord the error in- to which they had fallen, we have no means of knowing; but it was gratifying to observe that they abandoned a principle of adjudication which had not one single argument to recom- mend it. Three years afterwards Mr Babbage, i in his able and useful work on the “ Decline of Science in England,” went a step farther than we had done, and showed that the adjudication of the medals to Mr Dalton and Mr Ivory for discoveries made long before his Majesty had founded them, was in direct violation of the rules which the Council had laid down, and. had actually transmitted to the King through the Secretary of State for the Home Department. Although in this breach of their own rules the Royal So- ciety acted from the best intentions, and with the view of pro- moting the interests of science, yet the almost universal deci- sion of the public against the principle which they followed, and the fact of their having themselves renounced that prin- ciple in their future adjudications, must be held as at once a proof and a confession of error. Under these circumstances, we were surprised to observe that. the Geological Society had committed the very same error, by adjudging the first Wollaston Medal to Mr Smith for dis- coveries made long before it was founded. .As we do not know the terms of Dr Wollaston’s bequest, or the rules which the Geological Society have framed for their guidance, we are unable to determine whether or not they have acted in confor- mity with them; but even if the terms on which Dr Wollas- Adjudication of the Wollaston Medai. 359 ton bequeathed the money are sufficiently vague to authorize the principle of adjudication which has been adopted, we do not hesitate to condemn the principle, not only as highly inju- rious to the progress of science, by withdrawing a powerful stimulus from those who are engaged in geological pursuits, but as preventing the wealthy patrons of science from esta- blishing other prizes in future. When the principle of adjudicating medals for rewarding old discoveries is once admitted, the difficulty is to fix the re- trospective limit at which we are to stop. The principle, in- deed, does not admit of a limitation, for there is the same reason for rewarding a discovery sixty years old as there is for. rewarding a discovery made only ten years ago. The principle, however, is in itself untenable, and if it is followed out, the medal must be adjudged in successive years to Sir James Hall, Professor Buckland, Professor Sedgewick, Dr MacCulloch, Dr Hibbert, Mr Poulett Bevape, Mr Lyell, Mr Murchison, &c. If foreigners are admitted to competition we might adda list of distinguished names, with Von Buch, Cuvier, Brongniart, Cordier, &c. at their head; and until all these veterans had been crowned by the Geological Society of London, every young aspirant after fame would be deprived of the just res compense of his labours. It is, we think, peculiarly unfortunate that, in the present degraded and declining condition of English science, the few rewards which genius can command are not judiciously con- ferred. Some individuals who are actively engaged. in scien- tific inquiries are not even aware of the existence of such re- wards, while others are wholly ignorant. of the conditions up- on which they are founded, and the periods at which they are awarded. In place of, its being left, as it now is, to the dif- ferent societies to whom the prizes belong to find out the in, dividuals who deserve them, these individuals should be en. couraged to bring forward their own claims, and to transmit memoirs and discoveries in express competition for the prize, along with certificates or opinions of eminent scientific men respecting the merits of their discoveries. As the council of the society, which has the power of adjudication, ¢annot al- ways be supposed to contain the individuals that are most dis. 360 Adjudication of the Wollaston Medal. tinguished in any branch of science, they would, by the me- thod which we suggest, not only be enabled to find out the most meritorious individual, but they would enjoy the satisfac- tion of having their own opinions confirmed by those of the most eminent philosophers in the land. We make no individual allusions when we state that the different prizes founded in Great Britain for the encourage- ment of science have not yielded those benefits which they were so well fitted to bestow. Of whatever blame has been thus incurred, the Royal Society of London must take to itself the greatest share, only because it has had the greatest number of prizes to confer. Even in the golden age of that institution, when it was adorned by Davy, and Young, and’ Wollaston, the council often found itself at fault in the adju- dication of their prizes; and in place of consulting individual members of the society, who could have aided them with their opinions, we can state, on the highest authority, that they sought for an approval of their adjudications from the philo-* sophers of Paris, and that, too, under circumstances where it was peculiarly improper to have done so. In the year 1820, the council of the Royal sodetyive ventured upon an innovation, by adjudging the Copley medal to Pro- fessor Oersted for his celebrated electro-magnetic discoveries. . This medal had been hitherto appropriated to the best paper or series of papers printed in the Philosophical Transactions, and its history was identified with that of the Royal Society itself. ‘Io divert it, therefore, from its original purpose, and to give it to foreigners, however distinguished, was a stretch of power which cannot be too severely blamed. ‘The Royal Society of London was not more called upon to do honour to the distinguished Danish philosopher than any other learned academy in Europe; and if they did feel it their duty to outdo other institutions in liberality, they might have done it~ out of their own funds, without breaking through a rule con- secrated by long custom, if not guarded by the positive terms of the bequest, and thus depriving the author of the best paper in the Z'ransactions for 1820 of his just reward. The Society cannot defend itself by stating that there was no paper of sufficient merit in the Transactions for 1820. Mr Adjudication of the Wollaston Medal. 361 Herschel’s memoir “ On the Action of Crystallized Bodies on Homogeneous Light,” justly merited the Copley medal of 1820; and though he did receive the same medal for 1821, yet this forms no justification of the rash innovation which we have mentioned. The same deviation from established usage has been made in subsequent years ; but it is enough for us to have pointed out the first false step of the Society. There is one other remark on these prizes which we think of some importance. None of the medals established in Great Britain have, so far as we know, been adjudged twice to the same person... This may perhaps be a very: good arrange-- ment ; but we believe it is in direct opposition to the intentions of the founder, as well as to the express rules laid down for their adjudication. If a medal is founded for the best paper in the Phil. Trans. for each year, there can surely be no reason why one person may not receive that medal twice, thrice; or. even four times; and if another medal is founded for the most important discovery in science made in any part of Europe during a period of either one or two years, it should be possible for the same person to receive it more than once. If the Royal Society have laid it down as a rule, as we be- lieve they have, that the same medal shall not be adjudged _ more than once to the same person, they must have done it on. the false supposition, that the medal is merely a badge of honour, a duplicate of which no person would be ambitious of wearing. But these medals are not marks of honour: They are substantial rewards, or pecuniary prizes, given not only to honour the successful inquirer by their public adjudication, but to indemnify him as much as possible for the expences in- curred by his scientific researches. In proof of this we have - only to state the fact, that almost all the large medals adj udg- ed by the Royal Society have been converted either into sil. ver plate or money. When science is. pursued by men of fortune, the loss of time, and the expence of apparatus and materials does not enter into their calculation ; and if it did so, it would perhaps not form a large item in their annual account, as it is not com- mou for such persons to devote much of their time to the ar. duous labours of original research. When a philosopher, 262 Prof. Airy on the nature of the Rings however, carries on his inquiries by the sacrifice of a half ‘or even a third of his whole. professional income, and when this Joss is increased by the purchase of expensive apparatus; the acquisition of a pecuniary reward cannot be unwelcome, inde-~ pendent of the honour with which it is accompanied. Upon this principle, prizes should always be adjudged to the person who really deserves them, however frequently he mer have been the successful competitor. . We would strongly recommend. it, theredonty to the Royal , Society to imitate the admirable example of the Academy of Sciences of Paris, in placing all its medals upon a distinct and. intelligible footing; and to publish an annual programme, stating the terms, and time of adjudication, and the various particulars which competitors might be desirous of knowing. | Whether this is done or not, we would suggest to the editors of that excellent work, The British Almanack, to publish an- nually in the Companion to the Almanack, a list of the va- rious. prizes, whether scientific or literary, which are annually adjudged by the different institutions in the country. Art. XIV.—On the nature of the Rings formed.by the double refraction of Quartz. By G. B. Airy, Esq. F. R. S$. Plu- mian. Professor of Experimental Philosophy, Cambridge.. Ar the meeting of the Philosophical Society of Cambridge held on the 21st of February 1831, Professor Airy read a pa- per on the double refraction of Quartz, of which the following is a correct abstract. We hope that Professor Airy has embark- ed seriously in this new investigation, and that his astronomical and professorial duties will not prevent him from devoting a portion of his time to a subject of such high importance. “Tt is well known to those who have followed the recent dis- coveries respecting the properties of light, that the phenomena exhibited by quartz are very different from those in any other substance of similar crystalline character—as for i instance calc spar. ‘Thus when exposed to plane polarized light, a plate of calc spar exhibits a series of rings of which the colours com- mence from Newton’s black at the centre ; _and these rings are > Sormed by the double refraction of Quarts. 363 intersected by a black cross: quartz, on the other hand, dis- plays a series of rings, the central point of which exhibits a colour different according to the thickness of the plate: there \ 4s No cross, but at a distance from the centre rudiments of black brushes begin to appear. Again in the case of calc spar, on turning the analysing plate the rings change in colour, but are always circular, and of unchanged dimensions. On turn- ing the analysing plate in the experiment with quartz, the rings become square figures, with a curious defect of symme- try, and dilate or contract continually. If we put together a plate of right-handed and a plate of left-handed quartz in the same apparatus, we obtain a most singular and beautiful ap- pearance, consisting of four coloured spirals cutting a number of concentric circles. “On exposing these substances respectively to light circular- ly polarized, the appearances are still more remarkable ;_ calc spar exhibits rings dislocated at each quadrant, with a grey cross ; while the colours in quartz are seen in the form of two spirals inwrapping each other, with no black or grey cross. “Professor Airy, after describing these phenomena, the most striking of which are new, proceeded to state and develope the hypothesis which they have suggested to him; of which the main point is this: that the two rays in quartz are elliptically polarized, one to the right, the other to the left: the major axes of the ellipses being respectively in and perpendicular to the principal plane. Calculations founded on this supposition represent with a very close agreement, the very various and complex phenomena which have been noticed ; and, what is more remarkable still, they not only coincide in the general facts,'but lead also to deviations from symmetry such as are ob- served to exist in the figures. ** After the meeting, Professor Airy exhibited, 1st, a model to illustrate Fresnel’s idea, that circularly-polarized light is form- ed from plane-polarized light (when the plane of polarization is inclined 45° to that of total internal reflexion) by retarding the undulations perpendicular to the plane of reflexion by one quarter of an undulation; and that double such a retardation shifts the plane of polarization 90°: which was also shown to be the fact with Fresnel’s rhomb. — 364 Analysis of Scientific Books and Memoirs«- 2d, A new polarizing machine: the advantages of which are ;—that complete rings may be seen with a very small spe- cimen.: that by placing the specimen in another position, the macled structure may be very well seen: that: circularly-pola- rized light may be used as well as plane: and that meeenant may be used as well as daylight. $d, An attempt to exhibit the coloured rings gs the light of heated lime ; which succeeded so far as to show the practi- cability of this application.” Apt, XV.—ANALYSIS OF SCIENTIFIC BOOKS AND ME. - MOIRS. I—A Rationale se the Laws of Cerebral Vision, comprising the poi of Single and Erect Vision, deduced upon the principles of Dieehtie iad Joun Fearn, Esq. London. Pp. 176. Many of our readers are no doubt acquainted with the pneumatological writings of Mr Fearn, and with the correspondence which they occasioned with the late Professor Dugald Stewart, and which has been published i in the Parriana, or notices of Dr Parr- Our illustrious countryman did not view the speculations of Mr Fearn with a favourable eye, and to Mr Stew- art’s great influence over public opinion, Mr Fearn attributes the total in- difference of his countrymen to his intellectual labours. He has therefore made a direct appeal to the philosophers of France, to whom he dedicates his present work ; and if it should merit their unqualified censure, he says he shall be content to have it supposed that his previous writings are of no better complexion.” Mr Fearn then makes a second appeal to the Lord Chancellor Brougham, and in a subsequent part of the work, he calls upon the Editor of this Journal by name, to avow his assent to the “ laws of cere- bral vision.” ‘ : The strictures on Mr Stewart’s conduct, in giving his opinion of the pneu- matological labours of Mr Fearn, have but little tendency to encourage others to undertake the same ungracious task ; but as Mr Fearn admits the principles of dioptrics to be well understood, and perfectly established, and asserts that his speculations are in no case contradictory to them, we shall enjoy the advantage denied to Mr Stewart, of being able .f to demonstrate the truth of our opinions. ' Mr Fearn’s work contains the following subjects : _Secr. I. Initiatory reasoning upon Data and Method. II. Of Single Vision from two ocular impressions. III. Of Erect Vision with two Eyes, involving the crossing and re-form ing of images behind both eyes. Sun-srcrron. Of the principle of the visual direction of objects. Mr Fearn on the Laws of Cerebral Vision, &c. 365 - IV. Of erect vision with a single eye, lnpolying the crossing and re-form- ing of images behind both eyes. . V. Of Vision without external objects. _ As the views of our author on all these subjects are original, and stand in direct opposition to the opinions of the most distinguished philosophers and metaphysicians, it would require a volume as long as his own to make our readers acquainted with them, and another volume of equal length to examine them in detail. Mr Fearn will therefore, we hope, be satisfied with an examination of his fourth mode of vision, which-he characterizes as ‘* a clear field of unoccupied ground, there not being the least evidence of its having ever been noticed, and far less discussed in any extant treatise on optics, that has fallen in my way. On the contrary, the total neglect or oversight of this mode ; or rather the avowed denial of it in the case of human vision ; is plainly implied in a variety of ways in the extant treatises on the subject. With regard to the reality of this mode, I do not antici-. pate the smallest aera ofan objection, when it comes to be een de- scribed.” The fourth mode of vision is announced in the fallowing formal proposi- tion, which we print in exact imitation of the original. Prop. 14, “ When we see an external object one-half of it with one eyes lind the other: half with the other ; tt is certain from the laws of dioptrics, that an impres« sion from ONLY ONE-HALF of this object is inverted in ONE eye, and an ima pression from the oTHER HALF of it is inverted in the orHER ; and the cons sequence of this is, that we ought to see, NOT THE WHOLE OBJECT IN THE NATURAL arrangement of its features ; but this object in TWO UNNATURAL HALVES, TURNED PREPOSTEROUSLY BACK TO BACK. But any such pre= posterous phenomenon as this we NEVER WITNESS ; and, therefore, we do NOT SEE IMMEDIATELY FROM THE INVERTED IMPRESSIONS IN THE EYES 5 but these inverted impressions are RE-FORMED AND RECTIFIED TO A NATUSs RAL ARBANGEMENT BY SOME CEBEBRAL MECHANISM WITHIN THE CRA= NIUM.” In order to understand this, let us suppose that we are looking at the. words COACH HORSES, which we may consider as representing a coach, and horses yoked to it. Let us then place the edge of a sheet of paper be~ tween H and H, the opposite edge touching the nose, so that when we close the right eye, we shall see only the COACH, and when we close the defé eye, we shall see only the HORSES. Now, since an inverted picture of the COACH, and also of the HORSES, is formed in each eye, a person. stationed behind the two eyes will see these inverted pictures thus, HOVOO SUSUOH. The coach and horses are now no longer in their natu« ral arrangement, as Mr Fearn expresses it; but in two unnatural halves, turned preposterously back to back; and as we never witness any such preposterous phenomenon, he concludes that we do not sce immediately from the inyerted impressions in the eyes. Hence he is led to presume the existence of ** some cerebral mechanism by which the inverted i impressions are reformed and rectified. NEW. SERIES, VOL, IV. No. 11. APRIL 1831. . ©. Aa 366 Analysis of Scientific Books and Memoirs. - ~ We shall now proceed to show how the two unnatural halves are made to form a natural arrangement v without recourse to any such mechanism. It is a law'of vision deduced from observation, and universally and de- ‘tnonstrably true; that when ‘a ray of light, issuinig from any point of an ex- ternal object, falls upon the retina, the point of the object from which the ray issues is seen in the direction of a line drawn perpendicular to the re- tina, from the point at which the ray falls upon it. Now, if from every point of every lefter in thé invérted words OVO) SASUOH; as delinea- ted in the retina, we draw lines perpendicular to the retina till they meet the paper before the eye, to which its two axes are directed, their termina- tions will actually depict the words COACH HORSES. Hence it follows, that the preposterous position of the inverted i images is absolutely necessary to their being re-formed in virtue of the law of. vision already mentioned. ' The phenomena of vision, such as. single vision with two eyes, and erect vision from inverted images, are as well explained as any physical phenomenon, and present no difficulties whatever to those who are willing to study the subject. with diligence and patience. From the general tone and character of Mr Fearn’s work, we cannot hope to convince him of the mistakes which he has committed. He considers, indeed, his views as be~ yond the reach of criticism, when he’says, “ I hope I may be allowed to affirm, that’ there is io fact in dioptriés, or in ‘any*department of optital science, that is more rigorously demonstrated than’ that of the recrossing _ and rectifying of images behind the single eye.” If this be true, philo= ~ sophers are fools, and philosophy folly, and Mr Fearn may hope to esta- blish a new school on the ruins of that of Boyle and Newton. Thus disappointed by the perusal of the first sections of Mr Fearn’s book, we hoped to find something deserving of praise in his fifth and last section, ‘‘ on Vision without external Objects,” a subject very little studied, and one on which it would be difficult to make numerous ate without stumbling upon some useful or important fact. The optical readers of this Journal will recollect that we have had occa sion to discuss thé analogous subject of the vision of impressions on the retina. These impressions, however, were made with strong light on the retina; whereas Mr Fearn has occupied himself principally with thé lumi- nous circles produced by pressure on the eye-ball, and he treats only of. the direction in which they are seen. He regards it as a most extraordinary phenomenon, that the luminous image is always on the opposite side of the eye-ball to that where the pressure is applied ; whereas this is the neces~ sary consequence of the law of vision, that when any point of the retina is acted upon, either by light falling on its inner surface, or by a pressure either on its inner or on its outer surface, light is seen. in the direction of a line perpendicular to the retina, at the point of action or pressure. Hence we explain all the phenomiena which he has described, and many more’ which have escaped his notice. Had he acted upon his eye-ball with a greater pressure, an experiment not very safe, he would have found that the pressure was propagated across the eye-ball to the opposite point of the retina, and that, in consequence of two opposite points of the retina being acted upon simultaneously by pressure on one point, two diametrically op~ Mr Cram on the Primary Colours. 367 posite luminous images are produced. This fact is very important, as it proves, that re on any part of the retina, either from within or with- out it, a luminous image, which is seen in the same direction as if the same point of the retina had been acted upon by direct light.. We regret very much that we are obliged to give so unfavourable an ac- count of Mr Fearn’s optical labours. If he will only leave the field of spe- culation, and, with some feelings of respect for the researches of his predeces~ sors, will devote himself to the hard labour of experiment and observation, we have no doubt that he will do something which will nisi him credit and reputation. Il.—An Experimental Inquiry into the Number and Properties of, Uie Primary Colours, and the source of Colour in the Prism. By. MAL SR .. Crom, Esq. Glasgow, 1830. Pp. 47. Ir is much to be regretted that so excellent a henins as. Mr. Leap _should have left his own science to speculate upon the subject of prismatic éolours, and undertake the hazardous task of overturning the splendid diss coveries of Sir Isaac Newton. After Mr Crum had, in 1822, discovered his principal fact, and drawn from it his most important conclusions, he learned that Dr Joseph Reade had, in 1816, published a volume entitled, ‘* Experimental Outlines for a New Theory of Colours,” in which this fact and these conclusions were distinctly contained ; but though thus deprived of all originality, he is so. convinced of the importance of the discover y@i% that he conceives he cannot better serve the cause of science than by rendering more obvious the truth of Dr J. Reade’s theory. The principal fact, the discovery of which is thus given to. Dr Reade, has been well known for more than a hundred years, and has been observed; studied, and explained by every philosopher who has repeated the experir ments of Newton. Mr Crum announces his deduction from it in the fol- lowing proposition: Blackness or Darkness consists of three colours, and these may be produced from it by the Prism. To prove this, he places a slip of black cloth aths of an inch broad and 4 or 5 inches long upon a sheet of white paper laid upon the ground. He then views it through a triangular prism held near the eye, haying its, axis parallel to the black object, and at the distance of four feet from it. Io this case the black object entirely disappears, and instead of it. three ob- jects will be obseryed of the three simple colours Llue, red, and yellow, This effect, which Mr Crum has represented in beautiful coloured draw- ings, undoubtedly takes place, and the only fact to be determined is, whence come the three colours. To suppose that they came from the black pa seems to us a most extraordinary perversion of intellect, ak darkns produce all the splendid colours of the external, world, why did t the aye mighty create light? ‘Mr Crum has not told us whether or. not the brillianey of the colours increases with the decpness of the black. The fact is, that the brightness of the colours increases with the brightness of the sheet of white paper on which the black cloth is laid, so that if the white paper is rendered 10, 20, ‘or 30 times more luminous, the 4/we, red; and yellow colours are made 10, 368 Analysis of Scientific Books and Memoirs. 20, or 30 times more luminous. Now, if the colours were produced from the black cloth, how does it happen that. their brightness depends on the white paper? The question cannot be answered, and the conclusion is in evitable that the colours proceed from the light which is emitted from the: white paper on each side of the black cloth. The red and yellow are pro- duced from the light on one side of the black cloth, and the blue from the - light on the other sides In this case these three colours, in place of being primary are all compound, and their composition has been explained by Dr Young im his Elements of Natural Philosophy, vol. i. p. 439, and il- lustrated-in fig. 422 of his 19th plate. The whole of Mr Crum’s speculations on colours are of the same de- scription,—they form one mass of error ; and will be eagerly laid hold of by certain foreign journalists to depreciate the character of British science. We did not expect-that Scotland was to furnish such a weapon for the use of her enemies. HI —Sections and Views illustrative of Geological Phenomena, By Henry T. pe LA Becue, F.R.S., F.G.S. Pp. 71. 4tos Tuts useful volume contains an interesting collection of geological facts addressed to the eye through the medium of forty lithographie plates, most of which are finely coloured. These sketches are collected from a great variety of works, some of which are expensive and beyond the reaclt ‘of ordinary geologists ; and the letter-press of the volume is occupied with succinct and judicious descriptions of the phenomena in sR in the plates. : In pointing out the vast importance of facts in the present state of geo- logical speculation, M. de la Beche makes the following admirable remarks, which every geological student ought to engrave upon his memory. “* It would be well if the geologist would, before he begins to generalize, place himself before a globe or map of the world, and honestly ask himself how much is really known of the structure of the surface of that world. The answer might be, that, if the whole known with ewactitude were placed. on the desert of Great Sahara, the area representing that desert would not be covered. Even of the countries which have been considered the best explor= ed, Great Britain, France, and Germany, how much remains to be examin- ed! ‘Yet in the face of this confessedly limited information, we are told how the whole surface of the world has been formed. Why not content ourselves for the present with an honest deduction from the facts before us? ‘The advance so made is no doubt slow, but it is certain, and the step gained is is firm. *€ The work of pioneers is certainly laborious, and little suits minds which desire to advance rapidly and grasp all at once; but as a large ac- cwinulation of facts must precede any just conclusions respecting the gene= ral laws which have governed the formation of the world, we of ‘the pre= sent day must, I am afraid, be compelled to perform the office of geological pioncers, ‘however laborious, and comparatively inglorious Lon oti may be. ** One of the principal objects of the following work is to induce geologists x Electricity. 369 ‘to present us with sections more conformable to nature than is usually done. Sections and views are, or ought to be, miniature representations of ‘nature, and to them we look, perhaps, more than to. memoirs, for a right understanding of an author’s labours, ** Among the sections here presented, there are doubtless many that are only approximations to the truth, but, as approximations, they may be va- luable, and add to our stock of knowledge.” Ant. XV1.—SCIENTIFIC INTELLIGENCE. I. NATURAL PHILOSOPHY. ELECTRICITY. . 1. On the Laws of Electrical Accumulation. By Mr Snow Harris, Plymouth.—In the first volume of the T'ransactions of the Plymouth In- stitution just published, Mr Harris has inserted an elaborate paper on the ** ].aws of Electrical Accumulation.” The following is a recapitulation of the facts which he considers to be established by his experiments. 1. An electrical accumulation may be supposed to proceed by equal in- crements. A coated surface charging in any degree short of saturation, recéives equal quantities in equal times, all other things remaining the same. The quantity passing from the outer coating is always proportional to the quantity added to the inner. 2. The quantity of matter accumulated may be estimated by the revolu- tions of the plate of the electrical. machine, supposing it in a state of uni- form excitation ; or it may be measured by the explosions of a jar connect- ed with the outer coatings. _ It is as the surface multiplied by the interval which the accumulation can When the surface is constant it is as the interval. When the interval is constant it is as the surface. It is also as the surface multiplied by the square root of the free action. ‘When the surface is constant, it is therefore as the square root of the attractive force of free action. 3. The interval which the adcunulstion can pass is s directly proportional to the quantity of matter, and inversely proportional to the surface. - It is as the quantity divided by the surface. - If the matter and surface be either increased or decreased in the same ot, ego the interval remains the same. If, as the matter be increased, the surface be decreased, the interval will be as the square of the quantity of matter. ' 4. The force of electrical attraction varies.in the inverse ratio of the square of the distance between the points of contact of the opposed conduc- tors, supposing the surfaces to be plain and parallel, or otherwise between two points which fall within the respective hemispheres at a distance equal to one-fifth of the radius, supposing the opposed surfaces to be spherical, 370 _Scientifie Intelligence. 5. The free actioti is in! a direct proportion to the square of-the riod of tater, and in‘an inverse proportion to the square of the surface. It is directly’ as the effect of the explosion « ona — gion me other things remaining the same. If the matter and the ‘surface inctease or dectease wligitade and in: ic sufié proportion, the attractive force of free action remains the same. If, as the matter be increased, the surface be decreased, the attractive force of free action is as the fourth power of the quantity of matter. 6. The effect of an electrical explosion on a metallic wire depends ex- clusively on the quantity of matter, and is not influenced bythe intensity or free action. It is diminished by accumulating the matter on a divided surface. It is as the square of the quantity of the matter. It is as the square of the interval which the accumulation can pass- It is directly as ‘the attractive force of ‘the free action, all other things remaining in each case the edme. It is as the momentum with which the explosion ene thie ieial: 7 5 : ; Il. CHEMIST RY. 2. Existence of Copper in Vegetables and Blood. — Sarzeau has con- firmed the discovery of Meissner, that copper exists in vegetables, and. he has obtained the following results: Niignaaieie. of om 1 Kilogramme of grey quinquine contains, 5 Madder, - 5° Coffee, green Martinique, s Coffee, Bourbon, — - 8 Common,. - 8 Wheat, ith - 4.7 - Farina, . - ‘ 0.7 Fecula of potaloes, - 0.0 — Blood, id) - eh & M. Sarzeau has found that 1 milligramme of copper may be detected by the cyano- -ferruret of een in I kilogramme of canada —Journ. Pharm. xvi. 505. 3. On the Inflammation of Phosphorub ina partial Vacuum. By A. D. Bacue, M. D. Prof. of Nat. Phil. and Chem. Col. Depart. Univ. Penn- sylvania.—In the last number of the Américan Journal of Science and Arts, (page 147,) I observed an’exfract from one of the foreign journals, in re- lation to the experiment of Van Bemmelen, with phosphorus in the rare~ fied air of the receiver of an air pump. The article from which that ex- tract is taken reached us in the Bulletin des Sciences Physiques, &c. about the same time with the first volume of the French translation of Berzelius’ Treatise on Chemistry, of which the article in the Bulletin is a notice. Having referred to the account of Van Bemmelen’s experiments, given by, . Chemistry Mineralogy. 374 Berzelius, it appears, that the cause assigned by their author to explain his results, was, objected to, and that,an _explanation was “still wanting ; jn search of this L engaged in a series of experiments still in progress. .For the present I would call your attention to a portion of .the facts exhibited c: by these experiments, which seem to me interesting. Van Bemmelen found that a stick of phosphorus powdered with resin or with sulphur, and placed on, cotton under the receiver of an air-pump, or exhausting the receiver was inflamed ; and that the. same. ¢ffect. was produced by wrapping a stick of phosphorus in cotton ;. then. Placing, it under the receiver and exhausting the latter. Its inflammation occurs when phosphorus alone is placed under dent re- ceiver and the.air within is rarefied. These experiments I have repeated many times. The inflammation produced by resin is, remarkably different from that which takes place when the sulphur is used. : In addition to the substances just mentioned as producing the inflam- mation of phosphorus ‘under the partially exhausted, receiver, of an, air- pump, I find, that the same effect is produced. by powdering with finely divided Charcoal, * Spongy platinum, Hydrate of potassa, Carbonate of lime, Antimony, | _ Lime, - : Nitrate of potassa, Arsenic, Magnesia, Nitrate of lead, _ Hydrate of baryta, Sil. fiuate of lime (fluor Per sulphuret of mercury, spar, ) Sulphuret of antimony, Silica, Muriate of platinum : _ and ammonia, Per-oxide of mercury, Chloride of sodium, . Boracic acid. Per-oxide of lead, Muriate of. ammonia, Per-oxide of manganese, Chloride of lime, The temperature being about 60° Fah. or above that point. Proceeding to an extension of the experiments to air of the natural den- sity at different temperatures, I found, that at about 60° F., Carbon, in the form of animal charcoal, or of lamp-black, causes the inflammation of a stick of phosphorus powdered with it: this takes place either in the open. air or in a close receiver of a moderate size. The fusion of phosphorus is produ- ced at about the same temperature by (among other substances, ) finely. di- vided platinum sponge, antimony, potassa, lime, silica, carbonate of lime, &c. These actions are, as was to be expected, aided by. an elevation of temperature above 60° F. These results, I am led to believe from a. partial, trial, will find useful application in eudiometry by meams of Phomphoras —dmerican Hour : No. 38, p. 372. ; ha th ’ ay III. NATURAL HISTORY, . a MINERALOGY. ee ee 4. On Xanthite and its erystalline form. By - Ww. Ww. een Assistant Prof: of Chem. and Min. U.S. M. ‘A:—Xanithite has been de- 372 - Scientific Intelligence. scribed as a new mineral species by Dr Thomson, from its chemical and some of its physical characters.* I have now the pleasure to state, that it ‘also differs in its crystallographical characters, from any mineral species hitherto described. Dr Thomson describes it as a mineral of “ a light grayish yellow colour, consisting of a congeries of very small rounded grains, easily separable from each other, and not larger than small grains of sand. These grains are translucent, and some of them indeed transpa- rent. The lustre of the transparent grains is splendent ; that of the trans- lucent grains shining. The lustre is inclining to resinous. The grains are rounded, but when examined with the microscope, they seem to con= sist of imperfect crystals. The texture before a powerful magnifier seems foliated ; but the grains are so small, -that it is not easy to make out: its true texture with accuracy. Specific gravity, 3.201. ‘* Easily crushed to powder by the nail of the finger. It is therefore soft. It does not scratch calcareous spar. Infusible before the ree per se. Nor did it fuse along with carbonate of soda.” - Dr Thomson found the constituents to be Silica, ~ - - = 32.708 . Lime, ~ - - - 36.308 Alumina, - - - ~ 12.280 Peroxide of iron, - - = 12.000 ‘Protoxide of manganese, - - ~ 3.680 Water, ~ * - . 0.600. . 97.576. and he considers it as essentially composed of 2 atoms of silicate of lime, and t atom of silicate of alumina. I have found the Xanthite at Amity, Orange Comite New at in laminated masses in the same rock in which it is disseminated in grains. These masses are very frangible, crumbling readily into grains, some of which can be cleaved into prisms of perhaps 1-20th of an inch in their li- neal dimensions. - The laminated masses when held to the light exhibit very plainly by reflection, the directions of the cleavage planes. It exh bits double refraction when a candle is viewed through a thin plate of it, by placing it-over a fine hole pierced in a card. It can be fused in small particles on a fine slip of platinum foil by the common blowpipe. When in fusion it intumesces, and gives a greenish ‘translucent bead, slightly at- tractable by the magnet. ‘With borax it gives a glass yellow when hot, but colourless when cold. - The cleavages are parallel to the sides of a doubly oblique prism, which is probably its primary form, as no other system of cleavage planes could be obtained. The reflective goniometer gave for the angles PonM - * 97° 30’ PonT ali liag «98° 08 M on T saabliitbiigi Ge Sab 107 30 * Ann. of the Lyc, of Nate Hist. of New York, for April 1828. Zoology. 373 The planes M: and T were not sufficiently brilliant to give the angles exactly ; but it is presumed that the variation is not very great.—Ameri= can Journal, No. 38, p. 359. ZOOLOGY. 5. Notice regarding the Salamandra atra. By Mr Starx.—The two specimens of this reptile presented to the Royal Society of Edinburgh by George Fairholme, Esq. ‘‘ were found very high on the Alps in the canton of Berne. They are perfectly black, frequent dry grounds, and have a slow crawling motion. I have not (says Mr Fairholme in a note which accom panied the specimens) seen this kind in any museum, even at Berne ; and it is not much known, probably from its only appearing a few weeks of the years The Chamois hunters call it Raggimulli, and consider it venomous ; but it appeared perfectly harmless when alive.” Mr Fairholme is not without reason in supposing that the present species is not much known ; for it is not alluded to by Cuvier in the first edition of the Régie Animal, probably from that celebrated naturalist never hav~ ing seen the animal. In the second edition of this work, however, the species is noticed at the close of the description of the Salamandra terres« iris, on the authority of Laurenti, in these words: “ There is found in the Alps a salamander similar to the common one, but entirely black, and without spots. Sal. atra, Laurenti, pl. 1. fig. 2.” The other French naturalists who have mentioned the Salamandra atra, do not appear to have been able, by the possession of specimens, to inden- tify them with the description and figure of Laurenti. Sonnini and Dau- din, long before the publication of the Régne Animal, had described the Black Salamander of the Alps as a separate species ; but their statements rested solely on the authority of the original describer. Daudin, in par- ticular, thus speaks of the Salamandra atra: ‘ Laurenti has described and figured this Salamander, which appears not to differ from the preced- ing species (the Salamandra terrestris) but in its colour, which is deep black, without any yellow spot, and in its being one-half smaller. This author informs us that the Austrians name it Lattermandl, and that it is found in holes or clefts in the mountains of Etscher, where the Salaman- der with yellow spots has never been observed. We ought, then, with Lau- renti and Sonnini, to regard this Salamander as a particular species, and not a simple variety, as Gmelin, Lacepede, Latreille, Schneider, and other learned naturalists have believed.” —Daud. Hist. Rept. viii. 225. I have not been able to procure a sight of Laurenti’s work containing the description and figure of the Sulamundra atra ; but there can be little doubt, that the specimens which Mr Fairholme presented to the Society, are those of the animal which Laurenti has described. ‘The locality of this spedies, at a certain elevation, joined to the total want of the coloured spots, and its diminutive size, distinguish the Salamandra atra from the common Sal. terrestris. The doubts of the French naturalists seem to have arisen from not having seen this apparently rare species. J. S. 34 Scientific Intelligence. . 6. Vision ofthe Mole. By Grorrroy Sr-Hriatke.—-Doés the mole Sée ? Aristotle, and all the Greek philosophers, thought it blind. Galen, om the other hand, maintained that the mole saw. | He affirmed that it has all the known means of sight. The’ question has been resumed in modern times. Naturalists have found the eye-of the animal. It is very small—not larger than a millet seed ; its colour is an ebony black; it is hard to the touch ; and can’scarcely be depressed by squeezing it between the fingers. Besides the eyelid which covers it, it is protected: by long hairs, which crossing each other, form a thick and strong bandage. Such an eye ought to be destined to see. But anatomists do not find the optic nerve. What use. could dni eye be of, deprived of a nerve, which in other animals trans- mits the visual sensations to the brain. This consideration naturally tends to restore the opinion of Aristotle and the Greeks, and to itiduce the belief that the mole does not abe i that its iui is only a radimental point, without use. Direct experiments, however, a at tides request of G. St-Hilaire, show most incontestibly that the mole makes use of its eyes, since it turns to avoid obstacles placed in its way: But if the mole sees, how is this ac- complished without an optic nerve. M- Serres was of opinion that the place of this nerve was supplied. by a superior branch of the ra 8 ana- logous to the ophthalmic branch of Willis- According to Geoffroy St- Hilaire, this change of fonction 3 in a ‘nerve, which it is not naturally destined to perform, does not exist. The mole sees by aid of a particular nerve, being unable, on account of the too great extension of the olfactory apparatus, to follow the direction which it takes in other animals, towards the tubercula quadrigemina, takes another di- rection, and anastomoses,’in the nearest point, (au plus pres,) with the nerve of the fifth pair*-Ann. des Sciences d’ Observation, i. 144. IV. GENERAL SCIENCE. . Great Scientific Meeting to be held at York. ahaha are now i ol for holding at York, in July next, a meeting of the culti- vators of science from every part of the British Islands. The object of the association is similar to that of the German Society, so fully described in this number. ‘The sittings will continue for a week. The Lord Mayor and the authorities at York have, as might have been expected, entered heartily into this plan, and the Philosophical Society of that city have kind- ly offered to charge themselves with any preliminary arrangements which. may be necessary. Scientific individuals who propose to attend or to become members of thé association are requested to communicate their intention to Joun Rosison, Esq. Secretary to the Royal Society of Edinburgh, who has undertaken to act as Secretary till the association be constituted. Such communications wal of course be post paid, 8. Observations on the influence of Cold on New-born Children.—Dt Tre- visan has been making researches in Italy, principally at Castle Franco, analogous to those of MM. Villermi, and Milne Edwards, in France. The General Science. | 875 conclusions at which he arrives, are:—In Italy, of one hundred infants born _ in December, January, and February, sixty-six died in the first month, fifteen more in the course of the year, and nineteen survived ; of one ~ hundred born in spring, forty-eight survive the first year ; of one hindred - born in summer, eighty-three survive the first year ; of one hundred born - in autumn, fifty-eight survive the first twelve months. He attributes this mortality of the infants solely to the practice of exposing them to cold air - a few days after their. birth, for the purpose of having them baptized at the — church. As wellas MM. Milne Edwards and Villermi, Dr Trevisan calls the attention of the ecclesiastical authority to measures suited to put a stop to such Sisasters,. without oy the ratte or practices of religion.— -- 9. Ossification of the Vitreous Humor.—M. Krekn has lately met with that rare case, the ossification of the vitreous humor. of the eye. ‘It occurred in a man seventy years old, who died of gastritis; the pre- paration is placed in the Strasburg Museum. ‘The left eye was healthy, but the right presented the following appearance :—The globe was dimi- nished in size, had lost its spheroidal figure, and presented the appearance _of four wrinkles or furrows, corresponding with the insertion of the recti muscles. It was heavy and hard. When a horizontal section was made from behind forward, the sclerotic was found to be very thick, particularly at its posterior part, near the entrance of the optic nerve ; the instrument was soon arrested by a hard body, filling the whole space of the eyeball behind the crystalline lens, and consequently occupying the place of the vitreous humor. Immediately within the sclerotic was the choroid mem- brane, distinct, and rather thicker than natural. The retina was unchang- ed; the solid body within was marked by the same depression which had been observed extemally. It was of a pale white colour, and was inter- nally of a cellular texture, like the cancelli of the long bones. The crys- talline was indurated and of a yellowish white colour ; the optic nerve - was wasted,—Jdem. 10. Zoological Weather Glass. (Mag of Nat. Hist. iv.-479.)—At Schwit- zengen, in the post-house, we witnessed for the first time, what we have since seen frequently, an amusing application of zoological knowledge, for the purpose of prognosticating the weather. ‘Two frogs, of the species Rana arborea, are kept in a glass jar about eighteen inches in height, and six inches in diameter, with the depth of three or four inches of water at the bottom, and a small ladder reaching to the top of the jar. On the ap- proach of dry weather the frogs mount the ladder, but when wet weather is expected, they descend into the water, These animals are of a bright green, and in their wild state, here climb the trees in search of insects, and make a peculiar singing noise before rain. In the jar they get no other food than now and then a fly, one of which we were assured, would serve a frog for a week, though it will eat from six to twelve in a day, if it can get them. In catching the flies put alive into the jars, the frogs display great adroit- ness.— Idem. 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IV. NEW SERIES. ACHROMATIC object-glasses for micro- scopes, Acid, mellitic; 183—Succinic, 183—Pa- ratartaric, 183 Accident if a mine of Bovey coal, 168 Adie, Mr, his meteorological register at Canaan Cottage, 188, 376 Aerolite of Georgia, 181 - Ankle-joint of the horse, on a peculiarity in the, 47 Antimony, and arsenic, on their combina- tions, 68—Plumose gray, 69, 71 Aubert, Colonel, on the spontaneous in- flammation of powdered charcoal, 274 Barometric instruments acting by com. ‘pression, 91, 329 Berzelius, M. on bodies with a like com- _position but unlike 5 abet 130 Boisjoslin, M., his life of Baron Fou- rier, 1 oid citeag Bournonite, 69 Brewster, Dr, on elliptic polarization, 136, 247—on the mean temperature of the earth, 300 Caffeine, account of, 230 Cerebral vision, notice of Mr Fearn’s book on, 364 Charcoal, powdered, on its spontaneous - inflammation, 274 Coal, brown, formation of, in the Lower Rheinland, 276 sf Copper, gray, or Fahlerz, 70 Crum, "Mr, his book on colouts noticed, 367 ; Diluvial wave, on its direction in Shet- land, 85 Electro-magnetism of metalliferous veins, 263 Fearn, Mr, his work on cerebral vision noticed, 364 Feldspar, glassy, 72 Forbes, J. D. Kisq. on barometric instru- ments acting by compression, 91, 329 Fourier, Baron, life of, 1 NEW SERIES, VOL 1V. NO. I. aPRIn 1831, . Fox, R. W. Esq., on the electro-magne- ~ tisny of metalliferous veins, 263 Germany, geological map of, 75. Glass, on its reflective powers, 53 Globe, on its mean temperature, 300 Goring, Dr C. R. on achromatic object- glasses for microscopes, 244 Grant, J. Esq., on the habits and struc- ' ture of a male and female’ orang-ou- tang, 27 Graves, Dr J., on a new peculiarity in the ankle-joint of the horse, 47—on the vertebrz of the whale, 5] Grossmann, M., on a remarkable water- spout, 165 Hamburg, meeting of the cultivators of natural science at, 189 Hartmann, Dr, his mineralogical, geolo- gical, and chemical notices, 68 ’ Hibbert, Dr, on the direction of the dilu- vial wave in the Shetland isles, 85—on the Brown Coal formation of the lower Rheinland, 276 Heat, M. Fourier’s theory of, 8 Horse, on a peculiarity in its ankle joint, 4 ; Institute of Egypt, 2 Iron sand, titaniferous, 73 Jamesonite, 68 Johnston, Mr J. F. W., ona new yarie- ty of mineral resin, 122—his account ‘of the meeting of the cultivators of natural science at Hamburg, 189 Kupffer, M., on the temperature of. springs on the Caucasus, 355 Leeches, mortality among, in storms, 184 Lithium, atomic weight of, 71 €, La his principles of geology reviewed, 3 Marshall, Mr S., his meteorological ob. servations at Kendal, 186 ‘ Matteucci, M., on the action of the vol. taic pile, 273) Ba Mellitic acid, 183 Bb 378 Metals, on their action upon light, 136, 247 Meteorological observations at Kendal, 186—at Canaan cottage, 188, 376 Meteor in Georgia, 181 - Meteorites in Tennessee, 182 Miargyrite, 68 Natural science, meeting of the cultiva- tors of, at Hamburg, 189 Newton, Sir Isaac, on ocular spectra, 75 New York, mean temperature of 29 places in, 77 Nickel Glance, 74 Noggerath, M., on an accident in a mine of Bovey coal, 168 Oersted, Prof. account of him, 228 Oken, Prof, account of him, 190 Okenite, 73 Orang-outang, on a male and female one, 27 Paratartaric acid, 182 Patents, Scottish, 185 Polarization, elliptic, on the phenomena and laws of, 136, 247 Polybasite, 69 Potter, R., Esq. on improved methods of casting and grounding specula for reflecting telescopes, 13—on the reflec- tive powers of glass, 53, 320. Prizes adjudged, 185 Pyrophyllite, 71 Resin, mineral, on a new variety of, 122 Salicine, 184 Scheererite, 73 Scientific meeting at York, notice of, 374 Seleniuret of silver, 74 Selenium, pure, 74 _ INDEX. Shetland, direction of diluvial wave in, 85 : Silver glance, brittle, 69 Silver, red, 69 Spectra, ocular, observed by Sir Isaac Newton, 75 Speeel illusions, account of four cases of, 261 Specula, reflecting, on improved methods of working them, 13 Spherical triangles, on improved methods . of computing them, 124 Spontaneous inflammation of powdered charcoal, 274 ~ Snecinic acid, 183 Sulphur, carburet of, 184 Sympiesometer, observations on the, 91, 329. Temperature, mean, of planetary spaces, 9 Temperature, mean, of the globe, obser- vations on the, 300—of springs on the Caucasus, 355 Temperature, mean, of a4 places in New York, 77 Thomson, Dr James, on improved me- thods of computing spherical triangles, 124 Titanium, atomic weight of, 72 Voltaic pile, observations on its action, 273 Waterspout, on a remarkable one, 164 Whale, on the vertebre of the, 50 Wollaston medal, observations on its ad. judication, 360 : York, proposed scientific meeting at, 374 Zinkenite, 68, 74 NOTICES TO CORRESPONDENTS. The Articles of Mr Porter, Mr Forses, Mr J. Verrcn, Mr Larpiaw, and Mr MaTHEson, and also several Notices of Books, have been Postponed till next Number.—Mr Marsyauu’s Meteorological Observations, which came too late for insertion in this-Number, will appear in the next. 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