תמונות בעמוד

· Mem. IX. and X. relate to the Longitudes of Venice, Kieli, &c. and to the Opposition of Jupiter and Saturn, November 1, 1774, and March 2 ; 1775By M. DE LA LANDE.

Mem. XI. Observations on Saturn in 1775, towards the Time of his Opposition. By M. CASSINI DE Thury.

Mem. XII. New Analytical Methods of calculating the Eitipfos of the Sun, the Occultations of the fixed Stars, and Planets, by the Moon, and in general of reducing the Observations of the Mosu made at the Surface of the Earih, to the Place seen from the Centre. Twelfth Memoir. By M. DIO IS DU SEJOUR. In this Memoir, which contains above an hundred pages, the learned Academician applies to the solution of several astronomical problems, the equations of the preceding ones. There are various im portant articles discused in this ample and moit elaborate Memoir, such as the errors occasioned by refraction, the inflexion of the solar rays, and the observations that are the most adapted to ascertain the quantity of the inflexion of those rays that pass near the limb of the moon. Our Academician moreover confiders the law by which inflexion varies relatively to the distance between the limb of the fun from that of the moon: He applies the preceding theories to the observations made at London, April 4th, 1764, by Mr. Short, and at Pello, by M. Hellant; and he offers some conjectures concern. ing the cause, which, in occultations of the stars by the moon, makes the star appear on the moon's disk.

Mem. XIII. An Eclipse of Saturn by the Moon, with the conSequences resulting from thence.' By M. De la LANDE.- XIV. Observation of the Occultation of Aldebaran by the Alcon, April 4th, 1775, at the Observatory of the Marine. By M. Messier. XV. On the tenth Comet, at the Observatory of the Marine, from the Month of August, to the int of December, 1769. By the same.—XVI. On the sixteenth Comet, at the Observatory of the Marine, Paris, from the 18th of August, to the 25th of October, 1774. By the same. – XVII. Occultation of the double Star 7 of Virgo ;-Conjun&tion of Saturn with the vioon, the same Day, and the Place of a Star of the seventh Magnitude, which must have been eclipsed the same Evening by the Moon. By the same. - Continuation of the Memoir, printed in 1774, concerning the greateji Digrellions of Mercury from the Sun, and chiefly towards the Perihelium By M. LE MONNIER.- XVIII. On the Disappearance of Saturn's Ring. By M. Le Gentil.'

This Volume is terminated by a very curious Memoir, sent to the Academy, by the Royal Society of Montpellier, composed by M. Pouget. It treats of the atteriflimens' or accessions of land, thar the coasts of Languedoc have been long and gradually gaining from the fea. These proceed from the great quantities of land, gravel, and flints, that are carried down the Rhone, which meeting with the rapid current of the Mediter


Tanean at the mouth of that river, are stopped in their passage to the sea, and thrown upon the coasts. The details in this Me. moir are curious and instructive.

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ART. II. Hiftoire de l'Academie Royale des Sciences, &c. i. e. The History and

Memoirs of the Royal Academy of Sciences at Paris, for the Year 1776. 410.o 1779.

GENERAL PHYSIC S. TO TEMOIR I. Concerning the extraordinary Cold felt at Paris,

a nd in all the Provinces of France, also in other parts of Europe, in the beginning of 1776. By M. MESSIER. This Memoir extends to 156 pages. The detail with which the laborious Academician relates his observations and describes the instru. ments he used in making them, is most ample and circumstantial. He employed eight thermometers, two with mercury, and sıx with spirit of wine, in order to observe the local differences of the cold in places shut up or exposed to the open air, in different expofitions and at different heights; and by reducing the di. mensions of these instruments to a common measure, he has fura, nished future obfervers with the means of knowing these thermometers again, and reconstructing them in time to come, that the degree of cold observed this year (1776) may not be loft, as that was which M. de la Hire observed in 1709.

M. Messier conpares with his observations those that were made in different places at Paris by order of the Academy.This comparison, which is attended with dificulty, on account of the difference of the times in which the cold rises to its highest term in different places, is followed by a table of the observations of cold made throughout Europe. From this ample table it appears, that the winter of 1776 was not accompanied with an uncommon degree of cold in the northern parts of Europe ; and that, even in Sweden and at Copenhaven, the cold was much less intense than ac Paris. It is to be hoped, that the daily improvements of meteorological instruments, and the increasing number of observers will give us, at length, some information with respect to the causes, hitherto unknown, of those variations in the winters that are quite independent on che latitudes of the countries where they are observable. Nor does our Academir cian omit the particular mention of the intensely cold winters that are spoken of by historical writers, Until the year 1709, they were only known by the vague observation of some of their effects: the winter of that year was observed with a thermometer ; but the method or art of rendering these instruments rura ceptible of comparison was then unknown; and unless we had the initrument that was employed in the observations of 1709, or which had been, at least, compared with the thermometer with which these observations were made, it must be difficult to ascerTi 4


tain the temperature of that year. It is much to be questioned whether there exifts an inftrument attended with these advanta. ges. Our Academician fixes the cold of that year at about 15 degrees.

His observations on the extraordinary cold felt in Paris and Senones, a town situated in a deep vale surrounded by mountains, are curious. They fhew, in a very palpable manner, what a very great difference in temperature local caules itay produce in different places, whole longitude and latitude are nearly the same. Still micre curious are his experiments on the effe&t of the direct action of the fun upon the thermometers, at different heights and in different temperatures observed in the lhade.

ANATOMY. Mem, I. Concerning the respeclive Situation of the large Vesels of the Heart and Lungs. By M. SABATIER. However unsuccessful all attempts towards an exact calculation of the animal motions have hitherto proved, it is nevertheless, certain, that these motions are conformable to the laws of mechanics. Thus, for example, the distribution of the vessels, which convey the blood to the different parts of the body, must be such, that the frequent adhesions of these vessels to each other may not occafion a prelfion that would be detrimental to the circulation of that fluid : that if the blood vessels envelope the trachea arteria, or bronchia, they may not, by contracting them, obstruct respiration ; and still farther, that if two vessels carry the blood into the same cavity, these two currents may not be impediments to each other. It is in this point of view that M. SABATIER examines the dif. ferent vessels of the lungs and the heart. There are no anaftomoses visible in the great vefsels of the human body, particularly in those that lie near the heart and the lungs; but the want of these is supplied by the respective fituations of thele veffels, which anatomical authors have not (says our Academician) hitherto defcribed with accuracy. He endeavours to do better. He begins by describing the situations of the vena cave, of the pulmonary artery, and veins ; of the aorta, the last of the large vefsels of ihe heart in the order of circulation. He proceeds from thence to make fome remarks on the position of ihe irachea or wind pipe, and on tbat of the bronchia, which, though they contain no liquid, must be counted among the pulmonary vessels.

Our Academician observes, with relpect to the two veins (venæ cavæ) which carry the blood into the right auricle of the heart, that though the one runs upwards, and the other downwards, yet they do not convey the blood in two contrary directions : He observes, that they have an inclination, wbich changes these directions, and makes them form an angle: that the blood of the vena cava ascendens, is naturally direéted towards the membrane which stops che faramen quale, so that the blood


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passes through this aperture in the fætus, and that, after having met with this membrane in adults, ic paffes into the right aus ricle, where it unites with the blood of the cava def.endens, whose motion, by this wife arrangement, it cannot impede. The great curvature, or arch of the aörta, comprehends, in its concavity, the right pulmonary artery, the trachea, the cesophagus, and the left bronchia ; but the action of the blood upon this arch of the aorta is only adapted to stretch it out, so that no pression can relult from thence upon the organs which it surrounds. The same difpofition secures the lateral parts or branches of the trachea, after their junction with the lungs, against the compression of the pulmonary veins.

M. SABATIER observes farther, that the curvature of the aörca produces in the spine, or back.bone, of many persons, a fimilar curvature, whose concavity is consequently towards the left; this curvature is sometimes nor very discernible, and at other times it does not exist. Tois is owing to the correspondent curvature of the aorta, which produces' this effect either by its pression, or by its preventing the equal growth of the spine. This phenomenon explains what our Academician has observed in perlons that are troubled with the rickets; namely, that the curvature of the spine extends its convexity towards the right. in examining the shape of most men, an attentive eye-will lela dom fail to difcover a small difference between the two sides of the body, wbich is very well accounted for by the observation already mentioned: This difference is the most palpable in men, and especially in women, whose professions require hard labour. It may be explained by the general custom of performing with the same hand all those kinds of labour in which the employment of both hands is not necesary. It might not be unworthy of the attention of anatomists to observe the direction of the curvature of the spine in perfons who have a natural propenfity to employ the left hand rather than the righr.

Mem. Il. Anatomical Observations. By M. Vico. D'Azyr. This Memoir contains two observations : One on a lubítance of an oval form, and full of hairs, found in the uterus.or womb of an unmarried woman of fixty-five, and the other on a fingular disposition of the vessels of the mesentery. There Observations are both curious: the latter is particularly worthy of attention. Our Academician difected a body in which the greatest anastomofis, which joins the two mesenteric arteries, was absolutely wanting. This observation, witli others that have been made on different part of the human structure, shew, that there is more or less latitude in the laws of Nature even in the forma. tion of individuals of the same species, who may live and exercise the same functions, with remarkable diversities of organization in the parts that perform them. We recom!nend this ob


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fervation to the spoiled children of Spinosa; and to the votaries of a blind and uniform necessity.

Mem. III. A Description of a Monfirous Child, with One Head and I'wo Faces, and I wo Bodies joined in their upper Parts, the one regular and complete in its conformation, the other imperfect. By M BORDENAUE. A woman belonging to ce village of. Brue nov, aged thirty-three years, after a labour of three days, was naturally delivered, the 23d of June 1775, of the Foetus, which is the subject of this Memoir. The Foetus was presented to the Academy of Sciences, and is represented at the end of the M'moir by four figures, that give a clear idea of the situation of its parts. The woman's delivery was long, though not labosious; for Nature had done the work before the arrival of the (urgeon. The navel-ftring, being weak, was broken during the delivery, and the child died through loss of blood and want of succour. On this the surgeon, turning all his attention to the afliitance of the mother, was surprised to find a second child, which was male, well formed, and lived three days after its birth.

The inspection of the other Foetus, which was manifestly a junction of two bodies, persuaded our Academician, that there was no anomalous production in the case, and that the one of the two, which was a rude mass, the face excepted, and which adhered to the thorax of the other, so as to make one substance with it, was no more than the remains of a Foetus that had not arrived at its full aelopement and formation. This detect he neither attributes to the force of imagination, nor to any thing originally monstrous or anomalous in the ovum, buc thinks it arole from tome casual preffion, or some of the various accidents to which two germs or principles of the Foetus are exposed in the time of cor,ception. He supposes, that thrce ova or germs were impregnated; two of which, by some accidental pression, contracted an unnatural union, which obstructed the progress of their organization, and occafioned the monstrous object here considered ; and he obferves, that these apparent disorders are no objections to the uniform proceedings of Nature, but are merely the effect of foreign causes, which disconcert her operations in the period of conception.

CHEMISTRY Mem. I. Refcarches concerning the Methods which are used by the Aslayers to fix the Standard of Gold in mixed Substances, and to de. termine at the same time the Quantity of Silver they may contain, as also concerning the Means that may be employed to improve this double Operation. By M. TILLET. in several Memoirs prelented to the Academy (in the years 1760, 1762, 3, and 9,) this laborious chemist had laid down a method of separating perfed from imperfect metals ; and here, to finish his plan, he points out the


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