THE MONTHLY REVIEW, For MA Y 1791. ART. I. Memoirs of the Literary and Philofophical Society of Manchefter. Vol. III. 8vo. pp. 674. with Plates. 75. Boards. Cadell. 1790. WE VE obferve, with pleasure, that this laudable inftitution continues to flourish and increase, and produce valuable contributions to fcience, to arts, and to general literature. The first two volumes of thefe memoirs were publifhed together in 1785. The fociety make an apology for the delay of the prefent volume, and inform us that, in future, one volume of mifcellaneous papers will be publifhed at least every two years.' PHILOSOPHICAL and CHEMICAL Papers. In one of the memoirs of the former publication, feveral facts were stated by Dr. Percival, with a view to establish an active principle of repulfion between bodies, in cafes where no fuch power has hitherto been fuppofed to take place; as in the violent agitation, or waving motion, which water exhibits under oil, when the glafs containing them is fufpended and made to vibrate *. His reafonings were combated at the time by Dr. Wall; and are, in our opinion, completely overturned by a paper in the prefent volume, viz. A Letter on Attraction and Repulfion; from A. Bennet, Curaté of Wirksworth, to Dr. Percival.-This gentleman, to whom we are already obliged for fome ingenious experiments in electricity, fhews clearly, that the agitation of the water, in the circumstances above mentioned, does not proceed from repulfron, nor from the different gravities of the two fluids, but folely from the different velocities neceffarily impreffed on the upper and lower parts; for one homogeneous fluid, water alone, undergoes the very fame motion at the bottom, which is ren * See our Review for May 1786, vol. lxxiv. p. 353. VOL. V. B dered dered fenfible by impregnating the lower part of the water with fome colouring material, or by dropping a coloured powder, as yellow ochre, into the water during the vibration: even a cylinder of wood, fufpended by its axis in a bent wire, exhibited, in vibration, a motion fimilar to that of the fluids. The author explains, very fatisfactorily, how the difference in velocity produces the phenomenon in queftion, on the common principles of motion. That drops of water roll over a colewort leaf without adhering, which has been confidered as another inftance of repulfion, he attributes to a blue powder, with which the leaves of these, and fome other plants, are covered; for if the powder be wiped off, the water will adhere: the leaves of honeysuckle and barberry are blue on one fide only, and water does not ad→ here to that fide, but does to the green one. He mentions fome other analogous appearances, and confiders more particularlythe attractions and repulfions of corks floating on the water. : Two corks, or other light bodies, fwimming on water at a distance from the fides of the veffel, if both be dry or both be moift, feem to attract one another: but if one be dry and the other moift, they recede; and if a dry one be driven against the fide of the veffel, it is repelled in a manner very much refembling the re-action of elaftic bodies. Now, a dry cork makes a depreffion in the water round it, from the non-adhefion of the water; and a wet one is furrounded by an elevated circle of water, raifed by capillary attraction. If two corks, in this laft circumftance, be placed fo near together, that the two elevated circles of water may meet, thefe circles attract one another, and, uniting, endeavour to form one circle, as two bubbles or drops of water unite and form one larger: this brings. the two corks together, which would alfo unite and form one larger cork, were they not prevented by the ftrength of cohesion between their own particles. Mr. Bennet applies the fame principle to the other fituations of the corks; and adds an ingenious conjecture, that as, in these inftances, repulfion is accounted for by the attraction of intervening fluids, perhaps the elasticity of the air, electricity, and all other elaftic fluids, may be explained in the fame manner, that is, by fuppofing the mixture of a fyftem of fluids, of which fome are capable of permeating glass and other folids, as light, heat, magnetism, &c. fo that when air, for inftance, is condenfed in a veffel, the finer fluids are forced through the fides, and fuffer the particles of air to approach nearer together.' Remarks on the floating of Cork Balls in Water; by Mr. Banks, Lecturer in Natural Philofophy.-This gentleman first ftates the facts with precifion, and then explains them, as Mr. Bennet & Bennet has done, from the action of the water only, but refers that action to the common laws of hydrostatics. A moift cork, for inftance, with its elevated circle of water round it, remains at reft; because the elevation, and confequently the preffure, are equal on all fides: but if another cork, fimilarly circumftanced, be brought near it, the preffure, he fays, is diminished on that fide, and they are forced together, with an accelerated motion, by the fuperior preffure of the water on the oppofite fides. We do not well conceive how the preffure fhould be diminished on the two fides that are toward each other, unless it be from the mutual attractions of the two watery elevations; and, in that cafe, the two explanations are fufficiently confiftent. Conjectures relative to the Caufe of the Increase of Weight acquired by fome heated Bodies, during cooling; by Thomas Henry, junior.-This paper does not contain any new experiments, nor any attempt to reconcile the apparently contradictory refults of fome that have been made on the fubject by others. The author confiders only thofe of Dr. Roebuck and Mr. Whitehurst, published several years ago, in the Philofophical Tranfactions (vol. lxvi.); the fubftance of which is, that large maffes of wrought iron, heated to a welding heat, and weighed in that ftate, were found afterward to gain, as they cooled, fucceffive augmentations of weight. Mr. Henry attributes this increase of weight to the calcination, and confequent abforption of air, continuing to proceed after the removal of the mafs of metal from the fire; for fome metals, he obferves, copper in particular, are found to calcine more rapidly in a moderate heat than in one which is more intense. This conjecture, as the author modeftly calls it, is one of those which commands affent as foon as it is propofed, and muft, one would think, occur to every perfon who understands the terms: it is alfo more extenfively applicable than the ingenious author feems to have perceived. He fays that the experiment of Buffon, in which an iron ball, weighed when cold, then heated to a white heat and weighed again, was found to have received a confiderable increafe, is directly contradictory to the preceding experiments, and that therefore fome fallacy mult have happened in it; whereas, it is not only confiftent with them, but is the neceffary confequence of his own principle; for it is impoffible to heat iron to a white heat, and remove it * We do not know that this is more remarkably the cafe in copper than in other metals: but it prevails in them all, and in a fufficient degree to deferve the notice as well of the operator as of the philofopher. B 2 from Land from the fire to the balance, without calcination and of courfe an increase of weight take place on the surface. Obfervations on the Knowlege of the Ancients refpecting Electricity; by William Falconer, M.D. F.R.S.-In this curious paper, Dr. Falconer has fhewn, at confiderable length, that the ancient philofophers knew more of the properties of electricity than is generally imagined; that they were not only acquainted with the attractive power of amber, and the lapis lyncurius, (fuppofed to be our tourmalin,) but likewife with the electric troke, communicated by the torpedo, and fome other fishes. They had accurately obferved the nature of this extraordinary influence, though they knew not to what general principle it ought to be afcribed. They notice the ufe which the fish makes of this property for its defence and fupport, and its power of tranfmitting the froke through wood, metals, hemp, flax, and water: they even defcribe the organs in which the power is lodged; and recommend the ftroke, imparted by the living torpedo, for the cure of feveral difeafes. Inftances are recorded of inveterate head-achs, and the gout, being cured by it. The learned author makes it probable, that even the method of drawing down the electrical fire from the clouds was known in ` very early times, particularly to Numa Pompilius, the fecond King of Rome; and that his fucceffor, Tullus Hoftilius, perished by unskilful management of fo dangerous a process. Numa was an Etrufcan; and the Etrufcans, we learn from Diodorus Siculus, applied themselves very eagerly to the study of natural history, and investigated the circumftances relative to thunder, more than all other men. Pliny alfo fpeaks of the calling down and repreffing of thunder, and of its having been brought down by King Porfena in Etruria, by means of fome facred rites. Numa himself was undoubtedly a man of science: he rectified the calendar, and, by intercalation, brought the lunar and folar years to correfpond. he was acquainted with the power of a concave fpeculum in concentrating the fun's rays, and it was in this way that the vestal fire was kindled : he inftituted religious ceremonies, and, among other acts, as Livy tells us, he erected an altar, on the Aventine mount, to Jupiter elicius, whom, it was faid, he had a power of drawing down from heaven, to explain what was portended by thunder and lightnings, &c. According to Plutarch, Numa, not being acquainted with the means of procuring thunder, which knowlege he was defirous to acquire, applied to the goddess Egeria, who taught him the method of drawing Jupiter, that is, thunder, down from heaven.-With regard to the death of Tullus Hoftilius, Livy fays, "on examining the commenta ries of Numa, and finding there certain occult and folemn facrifices performed Jupiter elicius, he fet himself to execute thefe in private but, from fome improper management, he not only failed of being favoured with any celeftial appearance, but was, through the wrath of Jove, excited by fuch improper rites, ftruck with lightning, and confumed, together with his palace." Pliny gives a like account, that Tullus Hoftilius, "while he was imitating, in an unfkilful manner, the process of Numa for drawing down lightning, was ftruck with a thunderbolt." All the hiftorians agree, that he perifhed in a ftorm, and during the performance of a private religious ceremony; and confidering the intent of these rites, which probably confifted of some proceffes that exhibited appearances of an electrical nature, the author thinks it is at least probable, that he really loft his life by his unfkilful management. Dr. F. takes notice of a remarkable paffage in Lucan, relative to this fubject. Arruns, a learned Etrurian, whom he had before defcribed as "fkilled in the motions of lightning," is faid to have collected the fires of lightning that were dif perfed through the sky, and to have buried them in the earth *." What is this, fays the Doctor, but the description of the use of a conductor, to fecure buildings from being ftruck by lightning? The author next proceeds to fome conjectures concerning the means or inftruments employed in thefe operations. He fhews that the Etrurians worshipped fpears, and were the inventors of that weapon :-that they might not employ a single fpear in fuch folemnities, but a number, or what Homer calls Jouponen, or a kind of forest of spears, (Odyf. i. 128.)—that the first places of worship were in the open air, and on mountains, or houfe-tops-that Numa did not build a temple to Jupiter elicius, but an altar, on a hill :—that if a number of spears, with the handles of dry wood, or of fome of the terebinthinate woods, which are bad conductors, were placed with the points upward, in an elevated fituation, they might exhibit a luminous appearance, and, in certain feafons, collect electrical fire fufficient to make a great difcharge. In fhort, no one, who is in the leaft acquainted with this fubject, can be at any lofs to conceive, how Numa might have produced, with fafety to himself, all the miraculous effects that are ascribed to him, and how Tullus might have loft his life by *Fulminis edoctus motus Arruns difperfos fulminis ignes to Lucan. Pharfal, i. 605, 607. |