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. To give only one instance of the utility of this new fpecies of Comparative Anatomy :--The urinary bladder, in adults, it is well known is contained within the pelvis ; fcarce ever rising above the os pubis, even when moderately inflated. Ing young subjects, on the contrary, it extends greatly beyond thit pelvis, reaching upwards almost to the navel. The Author obferves therefore that, as the Lithomotist ought to follow the thortest and least dangerous course to arrive at the bladder ; he ought, when operating on infants, to use the higher apparatus, in preference to the lower, or to the lateral operation : as in them the bladder presents itself immediately under the teguments of the abdomen, and at a very considerable distance from the perineum. • We may refer to this class a Memoir, in which M. Lassone gives a very particular account of the late inoculation of the King of France, Monsieur, and of the Count and Countess D'Artois. The operation was performed a la Suttonienne, and was followed with fuccels, and the usual favourable symptoms. As the subjects were all in perfect health, no preparation was thought necessary, except a week's flight regulation of their diet.
In one of the short anatomical observations annexed to this class, we are informed that a girl was Thewn to the Academy on April 13, 1771, who had no tongue, and yet spoke very well. The late M. de Jullieu is said to have met with an instance of the same kind in Spain. This subject too was a female.
The class of Chemistry contains only one Memoir, in which is given the analysis of a mineral water in Picardy.
ALGEBRA. This class contains four Memoirs, on the resolution of equations, the quadrature of curves, and other subjects depending wholly on analysis, and which are not susceprible of abriugment.
MECHANIC S. In this class are contained two Memoirs, in the first of which M. Lavoisier offers various observations and calculations relative to the project which has been long agitated, of conftruding a fire-engine for the purpose of furnilhing the city of Paris with water. In the second, M. Desmarest gives an ample detail of the obfervations made by him, on his visiting the various manufactories of paper in Holland, with a view to discover the particular circumstances or manæuvres to which the Dutch papers owe their manisest superiority, in certain eflential particolars, to those manufactured in France. in consequence of his researches, the results of which are here given, we are told that the changes and improvements which he has proposed, have been adopted by the French manufacturers.
among the fixed Stars above the Horizon of Paris, 1c. By M.
Those appearances in the heavens which have been denominated Nebulæ, or Nebulosities, may be divided into two classes ; the telescopical, and those visible to the naked eve. Some of both kinds, examined by the telescope, are found to be only clusters of fixed stars very near each other, but too distant from us to be fingly discernible without glasses; while others, of the telescopic kind, still exhibit the nebulous appearance, even when they are viewed through instruments of the greatest magnifying powers. From analogy however there is reason to believe that these likewise consist of fixed stars ; but which are placed at so immense a distance from our system, as to elude the powers of our best telescopes.
M. Messier, who has distinguished himself by the discovery of so many comets, has not been less successful in the detection of numerous nebulæ which had escaped the observation of preceding astronomers. This indefatigable Otserver undertook this inquiry in the year 1764, which he has since prosecuted with great diligence; generally cmploying for this purpose a reflecting telescope magnifying 104 times, and lately an excellent achromatic telescope of 31 feet focus, with a triple object. glass, of Dollond's construction. In this Memoir he gives a minute account of his discoveries, in the order in which they were made; annexing a complete table, cintaining the right ascensions, declinations, and dianieters, both of the nebulæ dilcovered by himself, and of those which had been observed by others.
The nebula in the middle of Orion's Sword is perhaps the most remarkable of these appearances. It was discovered by Huyghens in 1656, who gave a drawing of it in his Cyflema Saturnium. Picard, M de Mairan, and M. Gentil afterwards delineated it. The difference between their drawings furnish some grounds to suspect that this nebula is subject to variations, M. Messier bas therefore made an accurate draught of it on a large scale, wbich was presented last year to the King of France, and a plate of which accompanies this Article. It exhibits likewise the appearance and position of 30 stars, from the fourth to the eleventh magnitude, contained in the field of the telescope. By this accurate delineation, future observers will be enabled to discover whether any perceptible changes are hereafter produced in this nebuia. This drawing differs lo much from those given by Huyghens, Picard, &c. that one can scarce imagine them to be representations of the same phinomenon., App. Rev. Vol. lii.
• Belize Beside the nebulæ here described, the Author gives an ac. count of other appearances of a similar kind, which have been noticed by former astronomers, but which are not now to be seen. It is natural to suppose that some, at least, of these phe nomena have been comets, which were visble only through a telescope, and which, on account of their immense distance, could be seen only in a very small part of their orbits. MEMOIR II. Extract of a Journal of a Voyage into the Indian
Sea, undertaken by Order of the King. By M. Le Gentil.
M. Gentil was sent to observe the tranfit of Venus, in the year 1761, in the East Indies. Having through various accidents been prevented from properly observing this important phenomenon, which happened while he was at sea, and before he could reach the coast of Coromandel ; his zeal for the object of his million induced him to submit to a voluntary banishment of eight years continuance, and to remain in the Indies, in hopes of observing the transit of 1769. Fortune, however, completely frustrated bis spirited and laudable intentions with regard to this object, and in a manner peculiarly vexatious. It gives us pain to relate that this zealous Aftronomer, after having upon the whole traversed no less than 10,000 leagues, and after having waited eight years in the Indies, in order to have a view of the fun on the morning of the 3d of June, 1769, for the space only of a few hours, or even minutes, was at last completely disappointed. The sky, which had been clear every moining during a whole month preceding the phenomenon, and which continued so almost to the very inftant of abservation, was then suddenly obscured, and the sun completely screened from his view, in consequence of a tempeft, which lasted precisely the time of the transit: for to increase, if possible, his mortification, as soon as the transit was fairly over, the clouds disappeared, and the sun shone out bright; as it continued to do for several days afterwards.
M. Le Gentil appears, however, to have employed the long interval between the two tranfits, in making many useful or curious observations, relative to Aftronomy, Navigation, Geography, and Natural History. A few of these are related in this Memoir, which is only an extract from the journal of his voyage, the whole of which he intends hereafter to present to the Public. We shall briefly relate one or two particulars.
During his residence in the Indies, M. Gentil took some pains to inquire into the manners, customs, and religion of the Indians, and especially into the state of Astronomy among them; having received such accounts of their skill in that science, as greatly excited his curiosity. He became still more interested to prosecute this inquiry, on being an eye-witness to the facility and dispatch with which one of those whom he calls the
ehis Memoie whole of whiciely relate one om. Gentil corn of the
Tamoult Indians, improperly termed Malabars,' calculated an eclipse of the moon, which he proposed to him at random. The whole process, comprehending all the preliminary elements, did not cost this Eastern Sage three quarters of an hour.
M. Genuil immediately became his disciple, devoting one hour in a day to the study of the Eastern astronomy. Though he was obliged to receive all his lessons through the medium of an interpreter ; yet he was in a short time enabled to calculate a lunar eclipse, according to the method of his instructor, which appeared to him to be very simple and easy. With respect to its exactness, he observes that the error, in several eclipses of the moon calculated by the Indian rules, does not exceed 25 minutes of time. The tables, on which these Indian astronomers found their calculations, will be published in the account of the Author's voyage.
Though it does not appear from any of the remains of antiquity, that the ancient Chaldeans and Egyptians had any knowledge of the precession of the equinoxes, the Bramins are well acquainted with it. They suppose that the fixed stars move annually 54 seconds toward the East. On this basis their aftro. nomical calculations are founded; as well as their belief with respect to the age of the world, and the period of its future du. ration. It is difficult to determine whence they could derive their knowledge of the precession; as they are not conversant in practical astronomy, or regular observations, and attend to eclipses from no other motives than those of religion. If we suppose that they have derived it from the ancient Brachmans, who had discovered it in consequence of a long series of accurate observations ; it should follow that the annual apparent motion of the fixed stars is slower now than it was formerly. The Author endeavours to throw some light on this dark subjeet, by noting the conformity between the astronomical periods of the modern Bramins, and those (the Neros, and Saros) indicated by Berosus, the Chaldean. He at length fuppofes. that the Chaldeans must probably have been acquainted with the precession of the equinoxes.
We meet in this Memoir with another striking and well authenticated proof of the grand alterations or derangements which this globe has sustained in some former period. On visiting Don Antonio de Ulloa, at the Ile de Leon, that gentleman, well known by the share he had in measuring a degree under the equator, shewed the Author some petrified sea-shells which he had himself taken from a large bank or collection of them, at the top of the Cordiliers. At the place where this bed of sea-shells has been deposited, the mercury in the barometer ftood only at 17 inches, one line, and a quarter; and accord
ingly indicated this collection of marine exuvie to be elevated 2200 toises, or French fathoms, above the present level of the sea. Memoir III. On the Inequalities in the Light of Jupiter's Satel
lites, and on measuring their respective Diameters ; together with a Method of rendering the Observations of their Eclipses, made by different Apronomers, and with different Telescopes, comparable with each other. By M. Bailly.
We shall not dwell on this Memoir, as we bave already [in our goth volume, May 1774, page 353] given a pretty full account of the Author's letter on the subject of it, addressed to Mr. Maskelyne, and published in the 63d volume of the Philosophical Transactions. We shall only observe, that by M. Bailly's ingenious application of diaphragms to the apertures of telescopes (first proposed by M. de Fouchy) and by his attention to the several causes which affect the time of a satellite's apo parent immersion, he deduces the instant of its real immersion, its diameter, &c. whatever may be the height of the satellite above the horizon, its distance from the sun or earth, the magnifying power of the telescope, or the goodness of the observer's eyes.
The remaining Memoirs of this class are-A continuation of M. du Sejour's New Analytical Methods of calculating Eclipses of the Sun; being his Ninth Memoir on this Subject :-A Fourth Memoir, by M. de la Lande, on the Theory of the Planet Mercury :-Observations on the Comet of 1764, and of the second Comet of 1769, which is the 59th of those whose orbits have been calculated ; by M. Messier :-Observations on the Eclipse of the Sun on June 4, 1769, by M. Meffier, in which he observed very evident Inequalities on the Edge of the Moon's Disk, fimilar to those formerly observed by the Prince de Croy, at Calais : (See our 37th vol. September 1767, p. 173)-Some Obseryations on the last Transit of Venus, by the same Astronomer; and on the Sun's Parallax, by M. de la Lande; together with a few other astronomical obiervations of lels importance.
This volume contains no less than four Eloges; those of the celebrated Morgagni, M. de Mairan, M. Fontaine, and M. Petot.