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Pandere tenuïculos; et Alabra ferentia venti
ART. LI. A Treatise on ELECTRICITY: wherein its
various phenomena are accounted for, and the cause of attraction and gravitation of solids, assigned, &c. By Francis Penrose, surgeon at Bicester. 8vo. Is. Owen.
from whence the electrical fire and force are produced ; and then makes some observations to ascertain how it acts upon the animal frame, and it what disorders it is likely to be of benefit.
As to the cause of electricity in any body, he thinks it wholly owing to the friction or attrition of the air surrounding that body, when put in motion, and by no means to any effluvia proceeding from the body itself, as is the commonly received opinion. His reasons for fo thinking are, that air, light, and fire, being of the same substance or effence, an attrition, dividing or breaking air, produces light, and, if that action is still encreased, it produces fire. To prove this, he brings the follow experiments, viz. if you slide a wax-thread, or small rope, through your fingers, it will burn them. So likewise fire is produced,
by rubbing two hard bodies together, as two sticks, a coachwheel, a cable, &c. From
the same principle, viz, the violent attrition of the particles of air, he accounts for the firey Aakes, balls, &c. feen at sea in tempestuous weather, and called, Helena, Caftor and Pollux.
He brings several other experiments, all tending to prove, that heat or fire is wholly owing to friction or violent motion: and in order to make it appear, that air itself is of the same substance with fire, he observes, that fire cannot fubfift without air, and in porportion of air forced into the fire, in such proportion will be the force of the fire. Again, fire can only act on the outside of bodies next the air; for even the most inflammable bodies can only catch fire on their outermost surface and fire in action, if immerged in a body of the most inflammable matter, will be so far from kindling the inflammable body, that itself will be extinguished.
These experiments, he thinks, prove, that, whenever air is sufficiently divided or broken to pieces, light is produced: so that thelight or heat in electricity is no other than what may be produced several other ways. For the air being violently rubbed or ground to pieces between your hand and the glass globe, whirled briskly about, it appears in the form of light, expanded or sent off from the glass globe in the fame manner as light from a candle; which emission is continually supplyed by the common air pressing in between the rays of light, emitted from the glass ball. That this is the method by which it acts, feems very clear; for you may not only hear the hilling noise of the air pressing towards the globe, but also plainly feel it with your
hand. This rarefaction of the air produced by a violent motion, and the pressing in of gross air to supply its place, gives a very clear idea, according to our author, in what manner the sun is supported, how this terraqueous globe and the rest of the planets are made to move, and continued in motion; and also what is the cause of the attraction of the sun, earth, moon, and the rest of the planets, Thus our author accounts for all the phænomena of nature, as attraction, gravitation, and even the solidity of bodies, by the pressure of the atmosphere.
What is called the attraction of the earth, continues he, seems to be performed in the same manner as that of the glass globe in electricity: the explaining of which will give us a clear idea by what means heavy bodies are forced towards the terraqueous globe. This he does from mr.
Hauksbee, who says, “ If by the heat and rarefaction, consequent upon the attrition, the medium contiguous to the glass be made specifically lighter; then of course, to keep up the balance, the remoter air, which is denser, must press in towards the tube, and so carry away in the torrent) the little bodies lying in its way, thither also. The various irregularities in the excitation, or the emission and dircharge of the electrical matter, or light, from the tube, (which will be followed by proportional irregularities, in the motion and tendency of the denser air, towards the glass globe, by the hydrostatical laws) may be sufficient to account for the various uncertain motions of the little bodies carried towards the glass globe."
Here our author observes, that, as this account of mr. Hauksbee's is so very clear, it seems strange that he should allow the power of attraction to matter, as in some places he does.
After this he explains the gravitation of bodies towards the earth, from the same principles. The sun-beams near the surface of the earth, being reflected by the terraqueous globe, must by that means be in a greater quantity there, than at a distance from it; and fo divide, rarify, and expand the air next the surface, which rarifyed or divided air is forced off from the earth on all sides, by the pressing in of the air from above, which must of consequence drive every thing before it towards the earth. Hence it appears, that the cause of bodies descending towards the earth is not from any property either of the earth, or of the descending bodies, but entirely to their being forced towards it, by the surrounded air, in its said motion.
Mr. Hauksbee's reasoning, in regard to what is called the attractive and repulsive power of electricity, is certainly very juft; but our author's application, ofit, appears to us forced, and carried farther than the thing will bear. That the rarefaction of the air near the surface of the earth, and the pressing in of the more dense air, may be the cause of winds, we allow; but can by no means admit this to be the cause of gravitation and the folidity of bodies.
Mr. Penrose, in the last place, briefly bints at the disorders in which electrical operations are likely to do good or harm, In fevers, and inflammations of all kinds, he thinks the worst and most pernicious consequences may be expected from the use of electricity. But, on the contrary, as the nerves act by a subtile fluid passing thro' them, and, by reason of the closeness of their pores, admit no fluid whole
particles are much larger than those of light; the consequence of such a make must often be obstructions ; which, as the light in electricity is forced thro' our bodies and nerves, may be broken and removed by its power: of which there are many instances, especially in palfies and other disorders of the nerves.
ART. LII. Observations on Tacitus. In which his cha
racter, as a writer and an historian, is impartially confidered, and compared with that of Livy, By the reverend Thomas Hunter, vicar of Garitang in Lancashire. 8vo. 49. bound. Manby.
E shall not detain our readers with a long account
of this performance, but leave them to judge of its author's critical talents from a few extracts. The whole is divided into two parts. In the first part
of which mr. Hunter endeavours to make it appear, that Tacitus is a vain, ignorant, credulous writer, void of judgment and candour; and brings a variety of passages from him in order to support this heavy charge.
He introduces his work in the following manner: 'To vanity, says he, may we not ascribe his tedious digressions and frequent excursions into remote ages and distant nations, which have little or no connection with the Roman ftory, or the times, which he proposes as the subject of his writings ? I remember not to have met with any objection to Tacitus on this account, which I am the more surprised at, as the affectation here is so very apparent. He lets slip no opportunity, but catches at any little bint, and makes forced connections to run back into antiquity, to give his work the more venerable air, and at the same time display his own deep erudition.'
Having considered Tacitus's vanity and affectation of dabbling in antiquity, as he calls it, our author proceeds to examine his descriptions; and these, he tells us, are overlaboured, unnatural, and sometimes even mean. "He describes, says he, not as things really are, but gives them undue proportions, and annexes unnatural circumstances, to strike and amaze the more. He leaves nothing to the reader to imagine. All is enlarged and magnified even beyond the bounds of nature and decency. Whether he describes the works of art, or the products of nature, actions, passions, or persons, they must have something strange or great to command more notice, and raise the merit of our
author's writings.-If Tacitus is any where happy in his description, it is in the display of guilty greatness. Luxury refined and high-flavoured, royal debauch, imperial whoredom, feem as much adapted to his pen, as Livy is charmed with the virtuous part, with the amiable glory of the temperate Scipio, or the illustrious poverty of the rural dictator. Never writer had a happier pen at describing wickedness than our author. It is the most natural part of his writings. Were we to give room to the suspicions we fhall have presently occafion to blame in Tacitus we should fay he might have been an adviser and an actor in every villainous design, and a party in every lewd scene he represents.—Sir H. Savil has more than once charged our author with negligence in his descriptions ; but I rather think his fault or his misfortune was ignorance.'
He tells us, that Tacitus is perpetually endeavouring to affect his reader with indignation, pity, or surprize. But then, says he, his study to affect you appears fo plain, that it defeats his design. His aim is to make himself the most conspicuous personage of the story; and so far he gains his aim, that you never lose fight of him : but then it fares with him, as with an affected beauty, who, not content with the charms which nature has given her, calls in the help of art to catch all eyes, and loses admirers by too apparent a passion to gain them.
• To this vanity of our author to display himfelf and amaze his reader, I ascribe his fondness for the miracu. lous, his mixing natural with civil history, his credulity and falfhood. As his descriptions are extraordinary, and his passions extravagant ; fo his lies are egregious ones, and his prodigies most prodigious.'
After this he proceeds to fhew, that there is a great deal of meanness in the writings of Tacitus ; and then observes, that there is one quality in him, for which no sufficient apology has been, or can be made ; and which renders him perhaps the most disagreeable writer that a reader of any humanity can peruse. "'Tis that perpetual malig , nity, says he, and ill-nature which disposes him upon all occafions to censure, blacken and defame, and to give the worst meaning to actions capable of a kinder interpretation and a more candid sense.'
He tells us, there is very little in Tacitus that comes under the character of pure history, and that his writings confist of conjecture, reflection, dissertation, debate, eloquence, politicks, proverbs, antiquity, affectation, satire, neer, far