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Art. IX. Observations of a new variable Star. . By Jokn Goodricke, Esq.-Another variable ftar. This is B Lyræ, and its period is faid to be twelve days, nineteen hours. From the particular observations, it appears fomewhat less,

• As B Lyra is a quadruped ftar, No 3, of Mr. Herfchel's fifth class of double stars. I was defirous to see if any of the small ftats near it would be affected by its different changes ; but they seemed not to fuffer any alteration, either when it was at its greatest or at its leaft brightness. I attended to this the more particularly because the loss of the star's light was very confiderable, and the phænomenon seemed to be occasioned by a rotation on the star's axis, under a suppofition that there are several large dark spots upon its body, and that its axis is in clined to the earth's orbit.'

Art. X. On the Motion of Bodies affected by Fri&ion. By the Rev, S. Vince, A.M.--The object of this very ingenious author was to determine

"If, Whether fri&ion be a uniformly retarding force. • zdly, The quantity of friction.

• zdly, whether the friction varies in proportion to the prefe fore or weight.

4thly, Whether the fri&tion be the same on which ever of its surfaces a body moves.

It is well known how much philosophers have difered on this subject, and experiments have been scarcely more conclufave. Those of Mr. Vince are less exceptionable than many others, though fome doubts may still be raised. They are, however, inconsiderable ; and his conclusions may be fafely kooked on as a very near approximation to troth. In the first experiments it was found, that in hard bodies, fri&ion really was an uniformly retarding force. When the bodies were covered with cloth, woollen, &c. the retarding force increased with the velocity ; when covered with paper, it was again uniform. From the event of these experiments, the quantity of friction is easily determined by the laws of motion.

To determine the third queftion, the experiments are very properly directed, and it appears very conclusively, that the quantity of friction increases in a lefs ratio than the quantity of matter, or weight of the body. This determination en

tirely decides the latt queftion; for if the quantity of friction increases in a less ratio than the weight, there must be less friction on any given portion of the fmaller furface. But, as this opinion was very different from that generally received, it was put to the teft of experiment; and it appears very clearly that, with a given weight, the smallest surface has the least fiction. Mr. Vince thence thews the fallacy of his predecessors' experia

ments,

ments; and, as the proportional increase of friction, to the increase of weight, was different in different bodies, he purposes to examine the subject by future experiments, to determine the law of the increase. The paper concludes with five propofitions to establilh a theory on the former principles: Even to mention these more generally, would lead us too far,

[To be continued.]

FOREIGN ARTICLES. Histoire de l'Academie Royale des Sciences Année 1781, avec les

Memoires de Mathematique & de Physique pour la même Année,

Paris, 4to. 1784. A.

Ś we have lately added to our Journal an account of the

more remarkable and useful foreign publications, it would be inexcusable if we omitted the public transactions of the Royal Academy, and the Royal Society of Medicine. The object of the former inftitution is well known; and though we now again resume it, after a long series of successive publicacions, yet we need not go back to explain its origin, or to trace its progress. We purpose to follow the academy in their ensuing volumes; and where it may be necessary, shall explain any particular subject, by an account of what has been done in the former parts of this extensive series. The volume before us is not the last; but accounts only of that published about a month fince, have reached England. We shall not fail to attend to it as soon as we receive it.

In the department of General Physics, the first article is by M. Tillet, on the proportional Prices of Wheat, Meal, and Bread. This subject indeed belongs rather to æconomics than to physics; and we need not enlarge on it, because though some of the facts may be applied generally, yet a great part of the memoir is local.

The second essay, on the Comparison of Combustibles, is nearly of the same kind; but it is the work of Mr. Lavoifier, and deserves attention. He examined the heat produced, by the time which a given quantity of any combuftible would support the ebullition of a given quantity of water, to which fresh water was continually added, to supply what was lost by evaporation; or, fecondly, by the quantity of the combustible employed. Each' method produced the same results : foffil charcoal was the strongeit, charred wood next in order, and then wood itself.

The state of every body, with respect to its principles, is attended with a change of its state of temperature and electricity. In separating inflammable and nitrous air from metals, and fixed air from chalk, the remainder acquires a very sen

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fible negative electricity. Water in evaporation is almost always positive.

This is the only memoir on the subject of electricity.

In lighting public theatres, Mr. Lavoisier recommends elip.tical reverberators in the cięling, that no light may be loft, and the view of the stage not impeded.

In Anatomy, the first memoir, by Mr. Vicq d'Azyr, con tains a description of the brain, fpinal marrow, and origin of the nerves, in man. This will be a most important work : it is now only begun, and is illustrated by plates ; but it cannot be abridged. In the future Numbers, the brains of different animals will be described. In Italy, consumptions are considered as infectious, and no body, to whom this disease has proved fatal, is allowed to be dissected in the public schools. Mr. Portal, with much reason, opposes this opinion, and contends, that the complaint is rather hereditary than infectious. He makes a distinction between accidental and hereditary phthisis, which we believe to be juft : in the first the bronchial glands are primarily affected, and the pulmonary ones in confequence : the hereditary phthisis probably first appears with an affection of the glands of the lungs. The same author opposes the usual distinction of apoplexy into fanguine and ferous. He very properly urges physicians to overlook it, and treat the patient according to the circumstances in which they find him.

On the Natural History of Animals, M. Daubenton describes the trachea arteria' of birds. This memoir we have already noticed in our review of Mr. Latham's Synopsis. In the fwan the trachea paffes through the sternum; in cranes it rises, and is turned back through this bone twice, so that it has four curvatures. In the Paragua, an American bird, it pafies through the whole length of the sternum, and rises to the top of it again, before it passes into the lungs. In the stone-bird, so called from a hard excrescence at the beginning of its beak (the cushew bird of Edwards) the trachea rises and finks twice on the outside of the same bone. . This configuration is not to allift the voice, for herons and cranes are not remarkable in this respect; it is not to facilitate their diving, for the stonebird never dives. We must wait for the explanation, till we have received more observations on the subject.

In the Botanical department, Messrs. Fougeroux and Daubenton correct a common error, that some very old timber work is formed of chesnut, which was on that account supposed to be formerly more common than at present, as well as larger. They show, that it is composed of a peculiar species of oak, very hard, durable, and uncommon, but of flow growth.

In Mineralogy, Mr. Gentil gives the observations fuggefted by long journeys and extensive observations, on the formation of mountains. The principal novelty, in this memoir, is, that corresponding angles between two neighbouring mountains are Rever found, but where the valley seems to have been formed

by

by the course of a river. The inclination of the strata, he tells us, is sometimes so regular, that it may be employed to measure the height of the mountain with tolerable exactness.

The next memoir contains the observations on mines of coal inflamed by accident, by the imprudence of the miners, or heat raised by spontaneous fermentation. The author describes several of these, which burn as long as any fael remains. , When a brook has been conducted into the mine, to extinguith the fire, whose heat is very sensible on the surface, it occasions a little eruption, the nature of which we 'now very well understand, and fall explain in another part of this article..

Some Miscellaneous obfervations follow. ; The first is on calces of iron, found in the schistus that lies over coal. They resemble precipitations of that metal by acids, and one, produced by M. Sage, was like the precipitate obtained by the fac, charine. The second relates to the means of making fetid bitumens aromatic: asphaltum, exposed to a strong sun, in a close vessel (we suppose of glass), resembles in its odour bén-' zoin. In the last volume, M. Fougeroux defcribed fulphur found in the rakings near the gate Saint Antoine : the ground was that oh which a naughter-house formerly stood. M. Morand found the same in the ruins of a house situated near an old sewer.

The aventurine,'in M. Sage's opinion, is a kind of quartz. It is chiefly made up of small grains of this stone, and to it owes its peculiar property, which is found too in fome species of feld-spath. M. Daubenton thinks that the stone, formerly called aventurine, was rather of the latter species.

The Chemical part of this volume is very interesting, and we have often had occasion to hint at it; we must' therefore rest on it with unusual care. In the first article, • On Vegetable Analysis, count de Milli explains the method by which he intends to analyse vegetable substances, and afterwards to extend it to the animal kingdom. There is a candour and generosity in his conduct in explaining the method, which hews that he is more solicitous for the advantage of science than for the honour of discovery. He now only explains his apparatus, and may be followed by chemists of different nation's." We lately, in our review of Fourcroy's Lectures, mentioned how little we were really acquainted with animal substances ; but we recome mended an attention to the spontaneous changes, and an exa mination of the different parts, rather than to the more violent separation by means of heat: we know that in this field a rich harvest of discovery may be reaped. The count's plan is not, however, very different. He employs a lamp furnace, by which he gives the substance to be examined a constant heat, from the temperature of the air to that of boiling water. The degree is known by the number of threads in the wick, which must be near, but not very exactly reach to the truth. In this apparatus the subftances underwent the different fermentations;

a part

1

fible negative electricity. Water in evaporation is almost al. ways politive. This is the only memoir on the fabject of electricity.

In lighting public theatres, Mr. Lavoisier recommends elip.tical reverberators in the cieling, that no light may be loft, and the view of the stage not impeded.

In Anatomy, the first memoir, by Mr. Vicq d'Azyr, con tains a description of the brain, spinal marrow, and origin of the nerves, in man. This will be a most important work : it is now only begun, and is illustrated by plates ; but it cannot be abridged. In the future Numbers, the brains of different animals will be described. In Italy, consumptions are considered as infections, and no body, to whom this diseale has proved fatal, is allowed to be dissected in the public schools. Mr. Portal, with much reason, opposes this opinion, and contends, that the complaint is rather hereditary than infectious. He makes a diftin&tion between accidental and hereditary phthilis, which we believe to be juft : in the first the bronchial glands are primarily affected, and the pulmonary ones in consequence : the hereditary phthisis probably first appears with an affection of the glands of the lungs. The same author opposes the usual distinction of apoplexy into fanguine and ferous.' He: very properly urges physicians to overlook it, and treat the patient according to the circumstances in which they find him.

On the Natural History of Animals, M. Daubenton describes the trachea arteria of birds. This memoir we have already noticed in our review of Mr. Latham's Synopsis. In the fwan the trachea paffes through the iternum; in cranes it rises, and is turned back through this bone twice, so that it has four curvatures. In the Paragua, an American bird, it pasies through the whole length of the iternum, and rises to the top of it again, before it passes into the lungs. In the stone-bird, so called from a hard excrescence at the beginning of its beak (the culhew bird of Edwards) the trachea rises and finks twice on the outside of the same bone. . This configuration is not to affift the voice, for herons and cranes are not remarkable in this respect; it is not to facilitate their diving, for the stonebird never dives. We must wait for the explanation, till we have received more observations on the subject.

In the Botanical department, Meffrs. Fougeroux and Daubenton correct a common error, that some very old timber work is formed of chesnut, which was on that account supposed to be formerly more common than at present, as well as larger. They fhow, that it is composed of a peculiar species of oak, very hard, durable, and uncommon, but of flow growth.

În Mineralogy, Mr. Gentil gives the observations fuggefted by long journeys and extensive observations, on the formation of mountains. The principal novelty, in this memoir, is, that corresponding angles between two neighbouring mountains are never found, but where the valley scems to have been formed

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