tion of our new planet be limited to 18" or 20", we may fully account for the lofs of the fatellites when they come within its reach; for they have very little light to lofe, or lofe it pretty fuddenly.-This contraft, therefore, between the condition of the Georgian fatellites and thofe of the brighter planets, feems to be fufficient to account for the phænomenon of their becoming invifible." The precife periods of the additional fatellites cannot be afcertained without a greater number of obfervations; but the author gives eftimates as the moft probable which can be formed by means of the data already determined. There are two other circumftauces, re lating to the Georgium Sidus, which the author's numerous and continued obfervations have enabled him to determine with accuracy and fatisfaction. Having fufpected that this planet was encompaffed with one or more rings, sefembling those of Saturn, he is now able to affirm, with confidence, that no fuch appendage exifts. Many obfervations, with different inftruments, af certain the flattening of the poles of the Georgian planet; whence we may conclude, without hefitation, that it has alfo a rotation on its axis of a confider able degree of velocity. "A new Method of computing the Value of a flowly converging Series of which all the Terms are affirmative. By the Rev. John Hellins, F. R. Š.” The Bakerian Lecture confifts of "Experiments upon the Refiftance of Bodies moving in Fluids. By the Rev, Samuel Vince, A.M. F. R.Ş."-Mr. V. confiders the action of water at reft on a body moving in it, and then the action of water in motion on the body at reft. The refult of his experiments in the former cafe, compared with the theory at different angles of inclination between the ftriking plane and the fluid, together with the correfponding powers of the fine of the angle to which the refiftance is proportional, is exhibited in a table. From this table it appears that the refiftance, which the theory fuppofes to vary as the cube of the fine, decreases from an angle of 90° in a lefs ratio than that, but not as any conftant power of the fine, nor as any function of the fine and co-fine, which Mr. V. has yet difcovered. Hence it follows that the actual refiftance is always greater than that which is dedu ced from the theory, affuming the perpendicular resistance to be the fame. In order to account for this difference, Mr. V. observes, that, in the theory, the whole of that part of the force which, after resolution, acts in a direction parallel to the plane, is neglected; whereas his experiments thew that part of this force acts on the plane. Befides, the refiftance of the Buid which efcapes from the plane into the furrounding fluid may probably tend to increase the actual refiftance above that which the theory gives. In the circumftances here recited, the former was found to exceed the latter nearly in the proportion of 3 to 2.-Mr. V. is not unapprifed that the refult of .numerous and accurate experiments, made by D'Alembert, Condorcet, and Boffut, very nearly coincided with the theory, as far as the abfolute quantity of the perpendicular refiftance is concerned:➡ but he obferves that, in his experi ments, the planes were immerfed at fome depth in the fluid; whereas, in theirs, the bodies floated on the furface; and he fuppofes that, at the furface of the fluid, the fluid from the end of the body may efcape more eafily than when the body is immerfed below the furface. He acknowledges, however, that this hypothefis does not afford fatisfactory folution of the difficulty.— Mr. Vince next proceeds to examine the refiftance of bodies in fluids. For this purpofe he made ufe of femis globes, and alfo of cylinders; and be infers, from calculations founded op his experiments, that the ayel scht. ance of a globe is to the refiftance 201 cording to the theory in the ratio of 4 to 3.-The fecond object of the author's investigation, in this papes, the action of a fluid in motion on i body at reft. After a description of the apparatus with which his experi ments were made, he subjoins a table, which thews the effect of a perpendicu lar force at every tenth degree of incli nation from 10 to 90, bath by experi ment and by theory. It appears from this table, that the refiftance varies as the fine of the angle at which the fluid Arikes the plane: the difference be tween the theory and experiment being only fuch as may be fuppofed to arile from the want of accuracy, to which the experiments muft neceffarily be fubject." Hence he deduced the proportion between the whole perpendicu lar refiftance by experiment compared with that by theory: and he found that the latter is to the former as 614 to is par 900. He then examines what this refistance is, compared with the refiftance of a plane moving in a fluid; and, from the data already affigned, he concludes that the refiftance of a fluid in motion on a plane at reft is to the refiftance of the fame plane, moving with the fame velocity in a fluid at reft, nearly as 6 to 5. Hence it will follow that "the refiftance of the planes, meving in the fluid with the velocity here given, is diminished about one-fifth part of the whole, by the preffure behind the body; but, with different velocities, this diminution muft increafe as the velocity increafes."-Having eftablished that part of the force which as in a direction perpendicular to the plane, Mr. Vince proceeds to enquire what part of the whole force, which as parallel to the plane, is effective. The refuit of a variety of experiments at different angles of inclination is ticularly noted, for which we must refer to his own account. While the water flowed perpendicularly against the plane of the apparatus at different depths, the refifiances were always found to be proportional to the depths, and, confequently, proportional to the fquare of the velocity; as is alfo the safe when the body moves in the fluid. "An Enquiry concerning the Source of the Heat which is excited by Fric tion. By Benjamin Count of Rumford, F. R. S. M. R. I. A.While this ingenious author was engaged in fuperintending the boring of cannon in the workshops of the military arfenal at Munich, his attention was attracted by the very confiderable degree of heat which a brafs gun acquires, in a fhort time, in being bored; and by the still more intenfe heat (much greater than that of boiling water) of the metallic chips feparated from it by the borer. "Whence comes the heat actually produced in the mechanical operation abovementioned? Is it furnished by the metallic chips which are separated by the borer from the folid mass of metal ? If this were the cafe, then, according to the modern doctrines of latent heat and of caloric, the capacity for beat of the parts of the metal, To reduced to chips, ought not only to be changed, but the change undergone by thema fhould be fufficiently great to account for all the heat produced. But no fuch change had taken place; for I found, upon taking equal quantities, by weight, of these chips, and of thin flips of the fame block of metal feparated by means of a fine faw, and putting them at the fame temperature (that of boiling water) into equal quanti- the flips of metal were put." From this experiment, which was fe- "Is it poffible that the very confiderable th This fuppofition is altogether impro bable and is contrary to other decifive experiments; which afcertain the fact that the capacity for heat of the metal, of 1 of which great guns are caft, is not fenhbly changed by being reduced to the form of metallic chips, in the operation of boring cannon. Befides, fuch change could only he superficial; and there fore, if the heat were produced by it, the cylinder would, by degrees, be exkaufted-but, in repeating the experiment feveral times, not the fmalleft fign of exhauftion in the metal could be difcovered, notwithstanding the large quantities of heat that were actually given off-As the heat generated or excited in thefe experiments was not furnished at the expence of the latent beat or combined caloric of the metal, the Count purfued his enquiries, in order to determine whether the air did or did not contribute any thing to the generation of it. He found that this was not the cafe; because the quantity of heat generated was not fenfibly diminished when the free accefs of the air was prevented. By the refult of another experiment it appeared that the generation of the heat was neither pre. vented nor retarded by keeping the apparatus immersed in water, This experiment exhibited fome very ftriking phænomena. The cylinder of the machine, which revolved at the rate of about 32 times in a minute, foon generated to much heat as to make the was ter that furrounded it fenfibly warm. In one hour its temperature was raised not less than 47 degrees, fo that it was 107 of Fahrenheit's fcale. In half an hour more it was 142°; at the end of two hours it was raised to 178°; at 2 hours 20 minutes it was 200°; and at a hours 30 minutes the water actually boiled It would be difficult (fays the Count) to defcribe the furprite and aftonishment expreffed in the countenances of the bye-ftanders on feeing fo large a quantity of cold water (i.. 2wine-gallons) heated, and actually made to boil, without any fire!" The event, however, he acknowledges (and in doing fo precludes every remark), could not be juftiy confidered as fur. prifing. By computations which are here recited it appears that the quantity of heat, produced equably by the fric tion of the blunt fteel borer against the bottom of the hollow metallic cylinder in the preceding experiment, was greater than that produced equably in the combuftion of nine wax candles, each of an inch in diameter, all burning at the fame time with clear bright fames. Thefe computations al fo fhew "how large a quantity of heat might be produced, by proper mecha nical contrivance, merely by the strength of a horfe, without either fire, light, combuftion, or chemical decompofition; and, in a cafe of neceffity, the heat thus produced might be used in cooking vic tuals."-"What is heat? Is there any fuch thing as an igneous fluid? Is there any thing that can with propriety be called caloric?" The heat produced, in the author's experiments, by the friction of two metallic furfaces, was not furnished by fmail particles of me. tal, detached from the larger flid maffes on their being rubbed together. It was not fupplied by the air, becaufe the machinery in three experiments was kept undes water, and the access of atmospherical air completely pre vented. It was not furnished by the water which furrounded the machi nery, because this water was continu ally receiving heat from the machinery, and could not, at the fame time, be giving so, and receiving beat from, the fame body; and becaufe there was no chemical decompofition of any part of this water. After having examined fome other fuppofitions with regard to the poffible origin of this heat, and obs ferved that the fource of it appeared evidently to be inexhauftible, the au thor adds, that "any thing which any infulated body, or fyftem of bodies, can continue to furnish without limitation, cannot poffibly be a material fubfiance; and it appears to me to be extremely difficult, if not quite impofi.be, to form any diftin& idea of any thing ca• pable of being excited and communicated, in the manner the heat was excited and communicated in these exper riments, except it be MOTION." "Account of fome Endeavours to afcertain a Standard of Weight and Meafure. By Sir George Shuckburgh Evelyn, Bart. F. R. S."-A pendulum has been propofed as a very convenient inftrument for this purpose; but many difficulties occurred in determining the actual centre of motion and of ofcilla. tion. In order to avoid thefe, Sir George, fo long ago as the year 1780, conceived the idea of "a pendulum with a moveable centre of fufpension, capable of fuch adjustments as to be made to vibrate any number of times in a given interval; and, by comparison of the difference of the vibrations with the difference of the lengths of the pec dulum (which difference alone might be be the fandard measure), to determine its pofitive length, if that thould be thought preferable, under any given circumstances." While he was deliberating how fuch a pendulum might be connected with a piece of mechanifin, fo as to number the vibrations without affecting them, he learnt that Mr. Whitehurst had accomplished the object. He therefore directed his fubfequent attention towards verifying and completing the experiments of that ingenious philofopher; and, with this view, he procured an excellent apparatus adopted to his purpofe. Befides the machine with which Mr. Whitehurft had made his obfervations (of which he obtained a temporary ufe), his other inftruments were a beamcompafs, or divided fcale, made by Mr. Troughton, and furnished with microscopes and micrometer, for the moft exact obfervations of longitudinal meafure, and alfo a very nice beam or hydrostatic balance, fenfible with the Too of a grain, when loaded with 6lbs. Troy at each end; an admirable timekeeper conftructed by Mr. Arnold; a folid cube of brafs, whofe fides were 5 inches, a cylinder of the fame metal, 4 inches in diameter and 6 inches high, and a sphere of brafs, 6 inches in dia meter. The feveral parts of his appa ratus are defcribed, with the affiftance of figures. Sir George began his application of them with afcertaining the difference of the length of Mr. White. hurf's pendulums, vibrating 42 and 84 times in a minute, by Mr. Troughton's divided fcale. He then investigated the weight of a cubic inch of diftilled water, in a known fate of the atmosphere. His next object was, to determine the proportion of these weights and meafures to thofe that have been ufually confidered as the ftandard of this king. dom. The chief authoritative ftandards of longitudinal meature are thofe pre. ferved in the Exchequer, in the House of Commons, at the Royal Society, and in the Tower. Of the fe feveral ftand. ards the author has given a very parti cular account. He obferves, that the first alone bear legal authority, and have been in ufe for more than 200 years; the loft are confidered as a copy of them. The two others are of modern date, and bear no ftatuteable authority; but, as they were made by Mr. G. Graham and Mr. J. Bird, auifts of acknowledged reputation, they are held in high respect. The mean length of Mr. Graham's ftandard made in 1742, compared with the scale divided by Mr. Troughton, was found to be 35,9973 inches. The standard of Mr. Bird, made in 1758, compared. with Mr. Troughton's divifions, was 36,00023 inches, the thermometer being at 64°. From a table exhibiting a comparative view of the Exchequer ftandard of 1588 and of Mr. Trough. ton's fcale it appears, "thar the antient ftandards of the realm differ very little from those that have been made by Mr. Bird or Mr. Troughton, and, confequently, even in a finance view (if one might look fo far forward), nothing need be apprehended, of lofs in the culloms or excife duties, by the adoption of the latter."--The author proceeds to fhew the proportion of the weights which he ufed, compared with the ftandards that were made by Mr. Harris, affay-mafter of the Mint,, under the orders of the House of Commons, in the year 1758. The mean weight of the Troy pound, which was the fandard adopted by Mr. Harris, appeared to be 5763,715 grains by Mr. Troughton's weights, the barometer being at 29,72 inches and thermometer 67°; and the mean weight of the 2 lb. Troy, the thermometer being 68°, was 11527,70 grains, and 1lb. 5763,85 grains; confequently, the mean weight of 1b, is deduced from all the trials to be 5763,78 grains: fo that Mr. Troughton's weights are too light by 1 in 1523,92 grains. On the whole, our author concludes that the differ ence of the length of two pendulums, fuch as Mr. Whitehurft ufed, vibrating 42 and 84 times in a minute of mean time, in the latitude of London, at 113 feet above the level of the fea, in the temperature of 60°, and the barometer being at 30 inches, is 59,89358 inches of the parliamentary ftandard, whence all the measures of fuperficies and capacity are deducible. He has alfo determined that, agreeably to the fame fcale of inches, a cubic inch of pure diftilled water, when the barometer is 29,74 inches, and the thermometer is at 66°, weighs 252,587 grains by Mr. Troughton's weights: or, on account of the correction above stated to be neceffary of in 1523,92 grains, 252,422 parlia mentary grains; whence all the other weights may be derived. The three objects which the author has accomplithed, by the elaborate inveftigation contained contained in this paper, are briefly as follow: "Firft, an invariable, and at all times communicable, measure of Mr. Bird's fcale of length, now preferved in the Houfe of Commons; which is the fame, or agrees within an infenfible quantity, with the an-, tient ftandards of the reaim. Secondly, A' standard weight of the fame character, with reference to Mr. Harris's Troy pound. Thirdly, Befides the quality of their being invariable (without detection), and at all times communicable, these standards will have the additional property of introducing the leaft poffible deviation from antient practice, or inconvenience in modern ufe." Sir George clofes this curious and elaborate paper of 50 pages with a table exhibiting the prices of various neceffaries of life, together with that of day-labour, in fterling money, and alfo in decimals, at different periods, from the Conqueft to the prefent time, derived from refpectable authorities; with the depreciation of the value of money inferred from them to which is added, the mean appreciation of money, according to a series of intervals of 50 years, for the first 600 years, and during the prefent century, at shorter pe riods, deduced by interpolation. This table is the refult of judgement and labour, and contains, in a mall compafs, much curious and interefting information. In an appendix we have an account of three other fcales, divided into inches or equal parts, and executed by the late Mr. Bird; one was the property of Gen. Roy, the fecond belonged to Mr. Harris of the Tower, and is now in the poffeffion of Alexander Aubert, Efq.; and the third was prefented by Mr. Bird's executors to the Royal Society. Thefe are compared with Mr. Troughton's fcale. We have also an examination of the ftandard-rod of Henry VII. conftructed about the year 1490, and a comparative view of the lengths of eight feveral ftandards and fcales, reduced to one and the fame measure, viz. that of Mr. Troughton. "Abstract of a Register of the Barometer, Thermometer, and Rain, at Lyndon, in Rutland, for the Year 1796, by Thomas Barker, Efq." and the Meteorological Journal of the Royal Society for 1797.” "Obfervations on the Foramina The befii of the Heart. By Mr. John A. bernethy, F. R. S."-By adverting to the circumstances under which the principal coronary vein terminates in the right auricle of the heart, we shall readily perceive that the flow of blood through that vessel must be occafionally impeded; and that the difficulty will be much increafed when the right fide of the heart is more than ordinarily dif tended, in confequence of any obfiruc tion to the pulmonary circulation. Such an obftruction, by diftending the right fide of the heart, and hindering the cir culation in its nutrient veffels, mut probably produce disease in it, if it were not prevented by that ftructure of the animal economy which the author explains in this paper. In the fequel of this paper the author explains another circumftance relating to the animal economy, which ferves to prevent difcafes of the heart that would otherwife inevitably fucceed obftruction in the pulmonary veffels. In fubjects who had been afflicted with pulmonary confump. tion for fome time previous to their dil cafe, the foramen ovale was found to be open; and, in several instances, the a perture was fufficiently large to admit the paffage of a finger. "As the feptum auricularum is almost con ftantly perfect in fubjects whose lungs art healthy (fays Mr. A.), I cannot but con clude that the renewal of the foramen ovalt is the effect of difeafe; nor will the op nion appear, on reflection, improbable; for the opening becomes cloted by the mem branous fold growing from one edge of it, till it overleaps the other, and their fimooth furfaces, being kept in clofe contact, by the preffure of the blood in the left auricle, they gradually grow together. But, fhould there be a deficiency of blood in the left auricle, and a redundance in the right, the preffure of the latter on this membraness partition will so stretch and irritate the uniting medium as to occafion its removal; and thus a renewal of the communicaties between the auricles will again take place." Hence the author concludes "that, in those men, or animals, who are cuftomed to remain long under water, this opening will be either maintained or renewed;" but the continuance of life does not depend on this circumfance alone; for, if the blood be not oxygenated in the lungs, it is not fit for fupporting the animal powers. Mr. Abernethy juftly controverts the truth of an experiment related by Buffo who fays that he caused a bitch to bring forth her puppies under warm water) and then fuddenly removed them int warm milk, in which flate he kept them for more than half an hour, and then took them out alive; and that the fubmersion |