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the West was on the increasing hand at that period. Since that time it has become stationary and may; foon (conjectures our Historian) assume a retrograde motion. He thinks, moreover, that the observacions that have been made on this subject seem to render it probable, that the extent of the variation of the needle is confined within the limits of an oscillation of about 30 degrees.
Memoir III. Remarks on the Temperature of the Cellars of the Observatory. M. Gentil, who went to India in 1760, carried with him three excellent thermometers, constructed by Mr. Micheli, which, all three, marked in the cellars of the Obser. vatory 10 degrees *; he brought back one of them, which in the same place marked 8 degrees à, both in summer and winter. In these observations, M. GENTIL compared the thermometer constructed by Mi. Sigau de la Fond with that of Micheli, and found, that the former 'marked 9 degrees while the lacrer remained without variation at 8 deg. <.
Α Ν Α Τ Ο Μ Υ. Memoir I. Concerning the Organs of the Circulation of the Blood in the Fætus. - It is well known, that, at the instant of the para fage of the fetus to a state of existence independent on the mo. ther, the circulation must undergo a remarkable change. In the foetus, the blood, which issues from the placenta by a vein, is carried back to it by arteries : at the instant of the birth, this vein and these arteries, which communicated with the placenta, are contracted, and grow almost impervious, and the blood opens a new paffage into the lungs.-The question then is, by what difpofition of the organs can a change of this kind be effectuated in a little time, and without occafioning any disorder in the animal economy? The solution of this interesting question is here atteinpred by M. SABBATIER, in consequence of new and interesting observations on the Valve of Euftachius, and the Canalis arteriosus.
Memoir Il. Concerning the Inequality in the Size or Capacity of the Cavities of the Heart and the Pulmonary Vessels. By M. SABBATIER.- This diverlity of size in the cavities of the heart (of which the right auricle is known to be of a larger capacity than the left) has been differently accounted for by different anato. mists. The various ways in which Helvetius, Michelocci, Sea nac, and Santorini, followed by Haller, explain this phenomenon, though all ingenious, do not fatisfy M. SABBATIER, who, after examining them with great attention, and shewing the Itrong cbjections and difficulties to which they are subject, propores his own account of the matter. According to him, the cavities, which are found unequal in dead bodies, are entirely equal in living ones : but those cavities, which, at the moment of death, contain the greatest quantity of blood, and on which
the blood has exerted its last action, must acquire then, and by these means, a larger capacity. M. SABBATIER has illuitrated and confirmed his hypothefis by a multitude of experiments.
Memoir III. Concerning the Analogy between the Ufes and Structure of the Four Extremities in the Human Body and also in Quadrupeds. By M. Vice D'AZYR.-We have here a new kind of comparative anatomy, in which the analogies and affinities between the different parts of the same individual animal are confidered. If the observation of the structure of the same parts in different kinds of animals open useful views to the anatomist, the confideration of the resemblance of different parts in the fame animal may have its utility; and our learned Academician has, certainly, an uncommon talent for this line of investigation. in this Memoir he compares the superior extremities of the human body with the inferior, and the anterior extremities of different kinds of quadrupeds with the posterior. Under this point of view he examines their bones, muscles, and vessels, and observes every where striking resemblances and diversities, which seem, in general, to depend upon the different functions which these extremities are designed to perform. Thus the thigh, the leg, and the foot, in the human body, resemble the arın, the fore-arm, and the hand; so that, with small variations of their position and shape, they may be brought to perform fic milar functions, and to execute all the motions necessary for the defence and nourishment of man, and the labours required in the different arts. The same thing is observable in the ani. mal kinds, where the resemblance is ftill more perfect, because the functions of their members are less diversified. The anatomical details into which our Academician enters, in order to point out these interesting analogies, such as his accurate parallels between the bones, muscles, nerves, and vessels that compose the extremities in question, are certainly instructive, and render the matter palpable enough. And this business may be rendered intelligible even to the vulgar, by the analogy between a kick and a cuff,-by the Jack-Pudding who walks upon his hands, and by the man whom we have seen writing Italian hand. with his foot. -The conclusion of our Academician is just with respect to the ceconomy and simplicity that reign amidst the diverlified operations of nature. In this new kind of comparative anatomy, as well as in the other, we observe (Pays he) "the two characters that NATURE seems to have stamped upon all beings, that of STABILITY in the type (or original form), and VARIETY in the modifications it undergoes. She (i. e. Nature) seems to have formed the different kinds of beings, and their correspondent parts, upon one and the same plan, which the has developed in an infinite variety of modifications, as me directs all the motions of the celestial bodies by one and the
memoir I. Concer Augmentation the design o fatisfactory outline
same force, whose effect, varying according to their respective diftances, produces all the phenomena which they exhibit to our observation. Such is the conclusion of M. Du Vice: and we take the liberty of concluding farther from from this, that Na. ture is a very sensible lady, and, if she does the business of herfelf, deserves at leaft, the honours of a Goddess; and then we Thall not dispute with the Atheist about the gender.
CHEMISTRY Memoir I. Concerning the Calcination of Tin in closed Vessels, and the Cause of the Augmentation of the Weight which this Metal acquires during that Operation. The design of M. LAVOISIER, in this Memoir, is to prove, by direct and satisfactory experiments, that the weight which metals are known to acquire by calcination is owing to the addition of air. Having calcined tin in retorts, hermetically sealed, after having weighed accurately both the tin and the retort, Mr. L. perceived, that in a certain space of time the calcination cealed; and that, though he continued the fire, he could not carry it on any farther : he then suspended the operation, and, weighing his retort before he opened it, he found that the weight of the whole had not changed : at length, opening the retort, he weighed the tin, whose weight he found augmented to the amount of some grains, while the retort, weighed separately, had the same weight as before the operation: the real augmentation of the weight of the tin was therefore derived from the addition of the air fhut up in the retort, since neither the weight of the whole together, nor the weight of the retort had at all changed. The calcination of metals does not therefore consist (concludes M. Lavoisier) only in the separation of their phlogiston from their earth; this calcination is accompanied with a new combination of their earth with the air ; the air is not only a mechanical, but is moreover a chemical agent in this operation, combining itself with the metallic earth, and disengaging from it the phlogiston.
Memoir II. Concerning a fixed Alkali, drawn from the Lixivium of the Kali. By M. Cader. producing
Memoir III. Concerning a new Method of semipfige Vitriolic Ether in greater Abundance, with more Facility," anet leis Expence, than by the Method that has been hitherto observed. By the same. The like quantity of spirit of wine in this new method produces a much greater quantity of the ether, than in the method hitherto practised. The new method consists in re-distilling new Spirit of wine a great number of times on the same acid. This operation may be repeated without any damage to the vessels : there must only be a glass stopple in the upper part of the recort, which must be carefully luted during the operation, and be taken out in order to pour in new spirit of wine. For a circumstantial description of this niethod, we must refer the Reader to
the work itself; one of the principal advantages of the operation of M. Cader is, that its residue, which the chemists usually throw away, is the matter that is capable of yielding the most ether.-It is certainly a valuable discovery to have hit upon a method of producing, without any augmentation of expence, from fix to nine times the quantity of Ether that the ordinary mechod yields.
NATURAL HISTORY OF ANIMALS. III. Memoir. Concerning the Anatomy of Birds, by M. Vice D'AZYR. We have here the conclusion of this Academician's labours on the bones and muscles of birds. In the two pre. ceding Memoirs he had gone through 14 of the 24 regions into which (as we formerly observed *) he divides the structure of that class of animals. The ten remaining regions, through which the ingenious Academician travels in this Memoir, are the abdomen-the external and internal regions of the ilium, the anus, the tail, and the thigh,-the anterior and posterior regions of the leg,che superior and inferior regions of the foot, and the region of the intercostal spaces. He follows his plan here, as in the preceding Memoirs, pointing out the analogy between the structure of the parts in a bird and a human body; shewing how the fame parts are differently modified in different kinds of birds; and, above all, observing with what admirable wisdom the form and position of each part are adapted to their respective functions and destination. He shews, among other examples every way proper to illustrate the doctrine of final causes, that the extreme length of that part in the ftructure of a bird which answers to the metatarsus in the human body, is absolutely neceffary to prevent the sternum from trailing on the ground--that the arrangement of its posterior parts is precisely such as is requisite in order to the expansion of its wings; and that the mechanism by which the bird can augment or diminish, at pleasure, the volume of its body, distribute through its various parts the air which it breathes, and thus change its specific weight, and diversify its center of gravity, is admirably contrived for these purposes. Our Academician unfolds the nature and powers of this mechanism in an ample and circumstantial detail; and confirms, by new elucidations, the existence and uses of the air that fills the bones of the animals in question. This latter fact was first conjectured by Aquapendente, and has been since proved by Professor Camper, whose laborious and fuccefsful researches entitle him to an eminent rank among the anatomists of our time.
* See the Appendix to the bit volume of the Monthly Review, P: 4946
MINERALOGY. Memoir. Concerning Gritt-stones in general, and those of For's tainbleau in particular. By M. de LASSONE. This is to be followed by a series of Memoirs on the same subject. We shall lay before our Readers a general view and result of the whole when they are all publithed. The discovery of crystallized gritts, first made by this Academician at Fontainbleau, opens a new field for researches. But when shall we know any thing of the principles and mechanism of crystallization? Ignoramus.
ASTRONOMY, Memoir 1. A CONTINUATION of the application of New Analytical Methods of calculating Eclipses of the Sun, the Occultations of Fixed Stars and Planets by the Moon, &c. By M. DIONIS DU Sejour.
Memoir II. Researches concerning the secular Equations of the Motions of the Nodes and of the Inclinations of the Orbits of the Planets. By M. DE LA GRANGE. This Memoir contains a new theory of the motions of the nodes and of the variations in the inclinations of the orbits of the planets; as also, the application of this theory to each of the fix principal planets. The astronomical Reader will here find general canons, by which the absolute position of these orbits, in any given time, may be determined, and, consequently, the true laws and principles of the changes to which the planes of these orbits are subject, be distinctly known. Our Academician seems very desirous that aftronomers should make use of these canons, as he thinks they may be of great use in accounting for the little agreement there is between ancient and modern observations. The canons that have been already given by other authors, for this purpose, are insufficient, as they only represent the differential variations of the places of the nodes and inclinations, and therefore, after a certain number of years, cease to be accurate; whereas the canons of M. DE LA GRANGE may extend to any number of years whatever. This Memoir contains also Tables of the secular variations of the obliquity of the ecliptic, and of the length of the tropical year, with the neceffary canons for calculating the secular variations of the fixed stars in longitude and latitude: these Tables take in the extent of twenty centuries before and after 1760.– There are allo 14 other Memoirs on astronomical subjects, by Messrs. MONNIER, MARALDI, BORDA, Du SEJOUR, MESSIER, CASSINI the younger, and Le Gentil.
The Memoir of the Academy of Montpellier (which is annually subjoined to the volume of the Academy of Sciences of Paris) contains also Astronomical Observations made by Messrs. DE RATTE and POITEVIN,