Lemonnier was not jealous of rivals. He recommended to Louis 15th Bernard de Jussieu, and chose that gentleman's illustrious nephew to supply his own place, when he was named Professor to the Botanical Garden. He likewise used his interest in persuading the Government to send naturalists to different parts of the world, in order to collect plants.

It was not until 1788, however, that Lemonnier, at the age of 71, was properly rewarded, and he was then appointed first physician. His method of practice (says his biographer) had more prudence than boldness: he rarely took a decisive part, and sought rather to observe than to control nature: he ordered few medicines; but the interest which he took in the situation of his patients was more effectual than physic; and he was remarkable for the attention with which he endeavoured to console them, and above all for the art of penetrating into the moral causes of their disorders: an art peculiarly estimable in the country in which he lived, where most of the disorders that afflict persons about the court originate in the mind."'

At the attack of the Tuilleries on the 10th of August, his life was saved in a singular manner. He concurred in the defence of the palace, till the royal family had retired to the National Assembly, and then he betook himself to a place assigned to him in the Pavilion of Flora. Soon he heard the cries of fury and despair; the door was forced, and the multitude rushed into his chamber, surrounded and menaced him he already believed himself their victim, and prepared himself for death, when an unknown and unarmed person called to him with a rough voice, seized him by the arm, and ordered him to follow:-"But the combat still rages," said he: "This is not the moment to fear balls" was all the answer given, and he was hurried rapidly over heaps of dead and dying, and amid the firing of the two parties. To his great astonishment, he and his conductor met no obstacle, and they arrived safely on the other side of the river: there the man, after having paused for a moment, said, "the battle is gain'd: I am no longer necessary I will accompany you to your dwelling ;" and he attended Lemonnier as far as the Luxembourgh, where the latter lodged. During their walk, he informed the amazed physician that he was an old soldier, induced by his political opinions to direct part of the attack, but that, struck with the venerable air of Lemonnier, he had conceived for him a sudden regard, and resolved to save his life.

The Revolution, which demolished every thing that was royal or antient, did not spare the place and pension of Lemonnier, but cast him at the age of seventy-five on the wide world, with only his library and collection of plants; his charities and botanical expences APP. REV. VOL. XXXVII. having

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having prevented all œconomical savings. Rather than expose to sale and resign what was dearer to him than life, he opened a small shop of botanical plants, and subsisted by cheerfully receiving a moderate salary from men on whom, in former times, he had liberally bestowed his gold and his advice.

This brief abstract of the present eulogy has already taken up so much room, that, greatly against our inclination, we are obliged to omit the interesting description of the young, the beautiful, the tender, and the pious wife of this worthy cha

racter.

ASTRONOMICAL and PHILOSOPHICAL MEMOIRS, &c.

On the Movement of the Orbits of the Satellites of Saturn and Uranus. By M. LA PLACE. From the observations of James Cassini (the son of the great Dominic Cassini), it appeared that the node of the orbit of the outermost satellite of Saturn was less advanced by 15°, than the nodes of the ring; and from these observations, with those of Bernard made in 1787, Lalande concluded the retrogradation of the node of the orbit to be 5 37" annually. M. LA PLACE, however, conjectures from the uncertainty of the observations, that Lalande's conclusion is not accurate; all that can precisely be ascertained from the observations is, that there is a retrogradation; and to calculate its quantity, from the theory of gravitation, is the object of the present memoir. The author begins his investigation from a formula demonstrated in his Mécanique céleste, a work of which we have already given an account *; and it is moreover of so abstruse a nature, that it admits neither analysis nor abstract.

Theoretical and Experimental Determination of the Forces which bring different Needles, magnetized to Saturation, to their magnetic Meridian. By M. COULOMB.-This memoir may be read with pleasure by those who are acquainted with the former researches of its author on this subject. (See Memoirs Acidz 1789.)

Memoir on the Theory of the Moon. By M. LA PLACE.- In the moon's orbit, there is a movement of nutation analogous to that of the terrestrial equator, and of which the period is that of the movement of the moon's nodes. The spheroid of the earth, by its attraction on that satellite, causes the lunar orbit to oscillate, in like manner as the attraction of the moon, on the spheroid of the, earth, causes our equator to oscillate. The extent of this nutation depends on the oblateness of the earth, and thus may throw great light on that important element.

*Rev. Appendix," N. S. vols. xxxi. & xxxii.

ad 32. There

There results thence, in the latitude of the moon, an inequality proportional to its mean longitude, and of which the coefficient is 6.5, if the earth's oblateness be

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This inequality amounts to the same thing as if we suppose the lunar orbit, instead of moving on the ecliptic, and preserving with it a constant inclination, to be moved with the same conditions on a plane passing through the equinoxes, between the equator and ecliptic, and inclined to the latter plane, 6.5, in the hypothesis of an oblateness = ; a phænomenon analogous to that which has been already observed in the orbits of Jupiter's satellites. (See LA PLACE's Exposition du Systeme du Monde, &c. book iv. chap. 6.)

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The comparison of a great number of observations had already indicated to M. Burg a periodic inequality in the movement of the moon's nodes; of which the positive maximum appeared to him to answer nearly to the years 1778 and 1795, and the negative maximum to the years 1768 and 1787; which is conformable to the progress of the inequality found by M. LA PLACE. M. Burg, however, had not determined the law of that inequality which at once influences the position of the moon's nodes, and the inclination of its orbit: the discovery of this law, then, is a new benefit to the theory of universal gravitation; and which, in this point as in many others, has preceded observations. M. Burg, in his memoir crowned by the National Institute, having engaged M. LA PLACE to investigate the cause of the anomalies which, from his observations, he remarked in the nodes of the moon, the result has been just announced, and is such as an analytical investigation affords. M. Bouvard has just finished comparing the result with observation; and 220 observations of Dr. Maskelyne, in which the preceding inequality was at its positive maximum, combined with 220 observations, in which it was at its negative maximum, have given him-7′′.5 nearly for its co-efficient; which corresponds to an oblateness in the earth equal to

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This co-efficient would be increased to 13".5, if the earth were homogeneous: its homogeneity, then, is excluded by the same observations of the moon.

The consideration of the preceding inequality has furnished M. LA PLACE with a new determination of the inequality of the moon, dependent on the longitude of the node. Observations had induced Mayer to admit this latter inequality, although it had not been indicated by any of the lunar theories; and he fixed it at 4" in its maximum. Mason, by the com

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parison of a great number of Bradley's observations, found it to be 7"; and, finally, M. Burg, by a great number of Maskelyne's observations, has lastly fixed it at 6.8. The existence of the inequality, then, appears incontestable. M. LA PLACE at first found, by the theory of universal gravitation, that at the most it was 2: but, having since ascertained the nutation of the lunar orbit, he perceives that its influence on this inequality is very sensible; and he finds that its co-efficient is to that of the preceding inequality of the movement in latitude, as nine times and an half the tangent of the mean inclination of the lunar orbit are to unity.

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This calculation gives 5".6, for the co-efficient, in the hypothesis of of the earth's oblateness: but it would be increased to 11.5, if this oblateness were 230; and, as all the observations give a smaller co-efficient, they concur with those of the moon in latitude, to exclude the homogeneity of the earth. The co-efficient 6.8, found by M. Burg, answers to an oblateness of which differs but little from the oblateness given by the inequality of the movement in latitude. It seems, then, that the comparison of a great number of observations of the moon, as well in longitude as in latitude, is capable of determining this oblateness with as much precision as direct measures; and it is remarkable that a continued observation of the movements of this heavenly body discovers to us the figure of the earth, the roundness of which it made known to the first astronomers by its eclipses. It results, moreover, from these researches, that the gravitation of the moon towards the earth is not exactly directed towards the centre of that planet, and is composed of the attractions of all its parts: which circumstance affords a new confirmation of the reciprocal attraction of the particles of matter.

Such is the curious and important investigation contained in the beginning of this memoir. The remainder is the analytical solution, founded on formulæ demonstrated in the Mécanique céleste.

Experiments calculated to determine the coherence of Fluids, and the Laws of their Resistance in very slow Motions. By M. COULOMB. When a body is impinged by a fluid with consi derable velocity, it appears by experiment that the resistance is proportional to the square of the velocity: but, in extremely slow motions, the resistance (which is no longer as the square of the velocity) is proportional to a function of that velocity; of which, when the velocity is increased, all the other terms, re

lating to that which expresses the square of the velocity, disappear. As, however, supposing the velocity to be very small, the quantity representing it is also very small, it is difficult to find its value by the ordinary methods, and still more so to separate what belongs to the different terms of the formula. This being understood, the object of M. COULOMB in the present memoir is to fulfil the two following conditions: 1. To employ a kind of measure by which it is possible to determine, almost exactly, the smallest forces.

2. To give, at pleasure, to the bodies submitted to experiment, a degree of velocity so small, that the part of the resistance proportional to the square of the velocity may become comparable with the other terms of the function representing this resistance or even, in certain cases, that the part of the resistance proportional to the square of the velocity should become so small, comparatively with the other terms, as to be safely neglected.

This is a very brief and imperfect account of M. COULOMB'S memoir; yet it may serve to give a general idea of its object. The description of the apparatus, the analytical processes, the conclusions, &c. occupy sixty pages; and the subject is to be farther pursued in a second paper.

On the Art of making Gun-Flints. By M. DOLOMIEU.-This art, it appears from the present memoir, is confined to a few communes of France, and is very little practised. In the foreign countries also, which he had visited, the writer knows of no place where the art is exercised, except in the territory of Vicenza, and in a canton of Sicily.-The memoir contains an analysis and description of the flint (silex pyromachus), a drawing of the few instruments used in the fabrication of gun-flints, and a description of the several processes.

On Mines. By M. MARESCOT, Associate.-The fortress of Mentz being menaced by the Austrians, the author of this memoir was sent to take the command of it: but, the Austrians retreating, he seized the opportunity of making certain experiments relative to mines. He had long entertained the notion that, if, instead of filling the stoves of the mines, a certain space was left about the charge, the effect would be increased; and that the air inclosed in that space, being much dilated by the heat of the inflamed powder, would join its elastic force to that of the gas disengaged in the combustion. His idea was confirmed by experiments; which, although they did not give results so decisive as he hoped to obtain, yet sufficiently shewed that spaces left round the stoves augment the force of the powder, and that the augmentation has a maximum.--The departure of the

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