On the Application of Liquids formed by the Condensation of Gases as Mechanical Agents. By Sir Humphry Davy, Bart. P.R.S. Read April 17, 1823. [Phil. Trans. 1823, p. 199.] The elasticity of vapours, in contact with the liquids from which they are produced under high pressures in high temperatures, is known to increase in a higher ratio than the arithmetical one of the temperature; but the exact law is not determined, and the loss of latent heat in compression, and the re-absorption in expansion, renders the advantage of steam under great pressure and at very high temperatures doubtful in an economical view. No such doubt, however, exists in regard to those fluids which require very great compression for their existence, and where common temperatures are sufficient to produce an immense elastic force. Thus sulphuretted hydrogen, which condenses into a liquid under a pressure of 14 atmospheres at 3°, had its elastic force increased so as to equal a pressure of 17 atmospheres by raising its temperature to 47°. Liquid muriatic acid at 3° exerted an elastic force equal to the pressure of 20 atmospheres, at 25° 25 atmospheres, and at 51° = 45 atmospheres. After some experimental illustrations of the expansibility of the vapour of sulphuret of carbon at different temperatures, the author adverts to the possible application of the difficultly compressible gases, as mechanical agents, and to their power of producing cold by the rapidity of their evaporation. On the Temperature at considerable Depths of the Caribbean Sea. By [Phil. In this letter Captain Sabine details the results of some experiments on the temperature of the Caribbean Sea, in lat. 2010 N. and long. 8310 W. At the depth of 1230 fathoms by the line, or about 1000 fathoms actual depth, a six's register thermometer indicated 45°.5, the temperature of the water at the surface varying from 82°.5 to 83°2, so that the difference amounted to 37°.3. Letter from Captain Basil Hall, R.N. to Captain Kater, communicating the Details of Experiments made by him and Mr. Henry Foster, with an Invariable Pendulum, in London; at the Galapagos Islands in the Pacific Ocean, near the Equator; at San Blas de California on the N.W. Coast of Mexico; and at Rio de Janeiro in Brazil. With an Appendix, containing the Second Series of Experiments in London, on the Return. Read April 24, 1823. [Phil. Trans. 1823, p. 211.] Captain Hall stated that the ship which he commanded had been constantly employed on a particular description of service, having no reference to such inquiries, but which occupied nearly all his time. It was only, therefore, at casual intervals that he could make use of the means placed in his hands, and many interesting opportunities were thus lost merely for want of adequate leisure to profit by them. The only stations, accordingly, at which the pendulum was swung in a satisfactory manner, were, 1st, the Galapagos Islands in the Pacific, lying 32 miles N. of the Equator; 2ndly, St. Blas, on the N.W. shore of Mexico, in lat. 211° N., and not far from California; and, lastly, Rio de Janeiro, the capital of Brazil, in lat. 22°55′ S. The ellipticity of the earth, resulting from the experiments made at the Gallipagos, is; but it must be observed that, as the nature of the ground on which the pendulum was here swung, was totally different from that of the stations at which it was swung in England, this result is not to be depended upon as giving a true expression for the ellipticity; since whenever a comparison is to be made between different stations on which the same pendulum has been swung, the circumstances ought always to be as nearly alike as possible in all that relates to the density of the ground. At the Galapagos, however, every thing was volcanic, and the islands were surrounded by a deep sea, whereas at the English stations the rocks were mostly primitive, and were surrounded by land. At the second station, San Blas, there were two series of experiments made, the first by Capt. Hall, which gave an ellipticity of, and the second by Mr. Henry Foster, one of his officers, .. These two series, however, were performed under circumstances so different, as to account sufficiently for the want of exact agreement in the results. During the first the temperature was steady, the sky always clear, and the rate of the clock uniform; but before the second series was well commenced the rainy season set in with great violence, the sky became overcast, few stars could be seen, the temperature fluctuated, and the rate of the clock became unsteady. The relative degree of credit, therefore, which attaches to the two series, is as 397 at 47, the amount of the respective factors, or nearly as 8 to 1, and we may assume the correct ellipticity at '.. At Rio de Janeiro, by Captain Hall's series, the ellipticity comes out, and by Mr. Foster's. The sum of the factors in this case being 148 and 304, or nearly as 261 in favour of Mr. Foster's experiments, the correct ellipticity may be taken at.. Captain Hall is of opinion that it would contribute materially to the determination of this question if the same pendulum were to be swung at places resembling the Galapagos, in geological character, such as the Canaries and Azores, Madeira, St. Helena, the Isle of France, and various islands in the Eastern Ocean; besides swinging it at stations resembling those of Captain Kater in this country, especially at the Cape of Good Hope, and at a port in the Falkland Islands, which happen to lie in the correspondent latitude to that of London, and afterwards as a check on the adjacent main land of Patagonia. Captain Hall announced his intention of instituting, in the mean time, some experiments for determining the actual effect on the vibrations of the pendulum, by changes of temperature, independently of any theoretical allowance. The portion of Captain Hall's letter, which was not adapted to public reading, consists of six series of observations at London, the Galapagos, San Blas, and Rio de Janeiro. These are given in the fullest detail, together with every attendant circumstance likely to have any effect on the experiments. Second Part of the Paper on the Nerves of the Orbit. By Charles Bell, Esq. Communicated by Sir Humphry Davy, Bart. P.R.S. Read June 19, 1823. [Phil. Trans. 1823, p. 289.] This is a paper in continuation.-In this part the author states that there are six nerves of the brain which go to the eye, while there are in all only nine nerves coming from the brain. He proceeds to show that each nerve has a distinct or appropriate function. The branch of the fifth nerve, called Ophthalmicus, bestows upon the parts within the orbit and the coats and surfaces of the eye, sensibility to pain, and that modification of sensibility which causes the winking and rapid motions of the eyelids and eyeball, and produces tears. It is shown that by the loss of this nerve the eye is deprived of its sensibility to touch and irritation, while it continues to enjoy the sense of vision, and the motions of the eye and eyelids remain perfect. Having shown that the motions of the eyelids depend on a branch of the seventh nerve, and not on the fifth, as hitherto supposed, and having proved in the former part of the paper that there is a corresponding motion of the eyeball and eyelids, necessary for the preservation of the organ, he proceeds to show that this connexion is established through the fourth nerve; that the fourth, or trochlearis, goes to that muscle which performs the instinctive and insensible motions of the eyeball, in sympathy with those of the muscles of respiration, and consequently with the eyelids. Having thus shown that the fourth, and a branch of the seventh, as enumerated by authors, perform the instinctive and involuntary motions of the eyeball and eyelids, he then explains the office of the third and sixth to be exclusively for the voluntary motions of the eye, and for directing the eyeball in subservience to its office of vision. By the discovery of the peculiar functions of the fourth, fifth, and seventh, the nerves of the head become thus arranged according to their uses: The first is the olfactory nerve. The second is the nerve of vision. The third is for the voluntary motions of the eye. The fourth for the instinctive motions of the eye. The fifth entirely for sensation of the head generally, and for the regulation of certain motions of the jaws. The sixth for the motions of one muscle of the eye. The seventh for the voluntary and involuntary motions of the muscles of the face. The eighth is the great respiratory nerve. The ninth, for the voluntary motions of the tongue. The nerve sometimes enumerated as the tenth of the brain, is properly the first spinal nerve: like those of the spine it has a distinct double root, and is a nerve both of sensation and of motion. In the end of the paper certain conclusions are drawn, which have reference to the subjects of the preceding papers of the same author. And here the author advocates the importance of anatomical investigation as superior to experiments on living animals, affirming that erroneous opinions in physiology have been sometimes strengthened instead of corrected by such experiments. An Account of Experiments made with an Invariable Pendulum at New South Wales, by Major-General Sir Thomas Brisbane, K.C.B. F.R.S. Communicated by Captain Henry Kater, F.R.S., in a Letter to Sir Humphry Davy, Bart. P.R.S. Read June 19, 1823. [Phil. Trans. 1823, p. 308.] In this communication, laid before the Royal Society at the request of Sir Thomas Brisbane, Captain Kater gives the results of experiments made by Sir Thomas Brisbane and Mr. Dunlop, at Paramatta, in New South Wales; and by Sir Thomas Brisbane, Captain Kater, and Mr. Rumker, in Portland Place, London, with an invariable pendulum belonging to the Board of Longitude. The number of vibrations made by this pendulum in a mean solar day at London, in latitude 51° 31' 8" 4, at the temperature of 60°, and reduced to a vacuum, was found to be 86090·17: at Paramatta, in latitude 33° 48′ 43′′ S., by Sir Thomas Brisbane's experiments 86021.59; and by those of Mr. Dunlop 86022.21. Captain Kater, after detailing these observations, proceeds to deduce the compression, and finds it, by comparing the vibrations at London with those resulting from Sir Thomas Brisbane's experiments at Paramatta, to be; by Mr. Dunlop's By the comparison of the vibrations at Unst with those at Paramatta, Sir Thomas Brisbane's experiments give, and those of Dunlop 01.0 for the compression. Mr. But the author remarks that these numbers are not to be deemed conclusive, as a small alteration in the number of vibrations made by the pendulum would occasion a considerable difference in the fraction indicating the compression. Observations and Experiments on the Daily Variation of the Horizontal and Dipping Needles under a reduced Directive Power. By Peter Barlow, Esq. F.R.S. of the Royal Military Academy. Communicated by Davies Gilbert, Esq. V.P.R.S. Read June 12, 1823. [Phil. Trans. 1823, p. 326.] By disposing magnets so as partly to counteract the influence of the earth's polarity on a magnetic needle, the author suspected that its daily variation might possibly exhibit itself in a very increased degree; and in experimentally prosecuting the idea, he found it to be the case to a very considerable extent in regard to the horizontal needle; and to take place also, though less satisfactorily, with the dipping-needle. In the former experiment a finely suspended horizontal needle was used, the directive power of which was reduced by two magnets, properly placed for the purpose; a deviation of 3o 15' was thus obtained at 11 A.M., which decreased to a late hour in the evening. The needle was kept in the same position for three days, with some change of directive power, with similar general results. After adverting to a difference in the direction of the variation in and out of doors, Mr. Barlow details the results of several experiments, which lead him to the following conclusions:-that while the north end of the needle is directed to any point from the S. to N.N.W., its motion during the forenoon advances towards the N.; and while directed towards any point between the N. and S.S.E. its motion is still to some point between the N. and N.N.W., so that there ought to be some direction between those limits in which the daily motion is a minimum: but whether this is a fixed direction during the year, or whether it has any vibratory motion as the sun changes its declination, is a question requiring further experiments to determine. Another conclusion which the author draws is, that the daily change is not produced by a general deflection of the directive power of the earth, but by an increase and decrease of attraction of some point between the N. and N.N.E., or between the S. and S.S.E. The variation of the adjusted dipping-needle did not indicate the gradually increasing and decreasing power manifested by the horizontal needle; and although it evidently is subject to diurnal change, the law of that change remains to be determined. On the Diurnal Deviations of the Horizontal Needle when under the influence of Magnets. By Samuel Hunter Christie, Esq. M.A. Fellow of the Cambridge Philosophical Society of the Royal Military Academy. Communicated by Sir Humphry Davy, Bart. P.R.S. Read June 19, 1823. [Phil. Trans. 1823, p. 342.] This paper contains a detailed account of a series of observations on the diurnal magnetic variation made upon the principle pointed out by Mr. Barlow, in his communication already before the Society. In regard, however, to the arrangement adopted by the author, it |