« PreviousContinue »
as our moral governor and judge, could be fo effectually preferved by the punishment of the penitent finners, as by rewarding the merits of Chrift with these God-like powers, which were neceffary to conftitute him a Prince and a Saviour."
The defign of the 6th letter is to fhew, that the christian fcheme, founded on the principles already established, is a regular, confiftent and rational plan of divine ceconomy, from the beginning to the end of the world; and for this purpose, our Author undertakes to prove the three following propofitions. 1. That the original defign of God from the beginning was, to bring all good men to falvation; that is, to eternal lite and happiness, by his fon Jefus Chriß: and the first cause and mover in this gracious defign, was the free grace and love of God.
2. That the method in which this falvation hath been car◄ ried on through all difpenfations from the beginning, hath been conducted by the miniftration of Jefus Chrift, under different names and characters; either immediately in perfon, or by his angel or angels.
3. That the efficient caufe or means, by which the falvation of man will be completed, will be the exercise of those God-like powers of raifing the dead, forgiving fin, and giving eternal life; which were conferred on Jefus Chrift by the Father, in reward of his humiliation, fufferings, and death.'
The feventh letter contains a collection of differtations on various fubjects; the opinions of several very respectable writers on the nature and end of the fufferings of Chrift are particularly examined: and, the Author having exploded the notion both of imputed fin and of imputed righteousness, inquires in what fenfe Chrift died for us, and what is to be understood by the terms ransom and facrifice, whereby he is defcribed in the New Teftament. He then digreffes into a comparison of the facrifice of Christ with the Mofaic facrifices; and into other incidental inquirics, connected with his main object. He concludes with ftating and obviating the principal objections of the Deifts; with evincing the probability of a divine revelation, for the purposes already affigned; and with an elaborate proof of the fall deduced from prophecy and miracles, that fuch a revelation has been actually granted.
In a poftfcript to this letter, our Author has examined Mr. Hume's notion of miracles; and he has clearly fhewn, that all the fpecious reafoning of this fceptical Writer, founded on an erroneous definition, and pointed against a fpecies of miracles which are no where recorded in Scripture, is foreign to the purpose: for though conftant experience fhould affure us (as Mr. Hume expreffes it) that the laws of nature are firm and unalterable (as they certainly are) yet there would arife from
thence no proof against miracles, becaufe a miracle is no violation of them.'
But we must clofe this article with recommending the perufal of these several letters at large, to thofe who defire farther fatisfaction on the interefting fubjects difcuffed in them.
ART. XI. PHILOSOPHICAL TRANSACTIONS, Vol. LXII. 4to. 7 s. 6d. Davis. 1774.
PAPERS relating to ELECTRICITY.
Article 39. Of the Electric Property of the Torpedo. In a Letter from John Walsh, Efq; F. R. S. to Benjamin Franklin, LL. D. F.R. S. &c. &c.
Article 40. Anatomical Obfervations on the Torpedo. By John Hunter, F. R. S.
HE curious and well authenticated facts and obfervations contained in these two papers, induce us to place them in the front of the prefent article, and to beftow upon them a more particular degree of confideration.
The electric fluid is now found to act fo important and multifarious a part in the drama of the universe, as almost to justify the very whimfies of those who have had immediate recourse to it for the folution of every phyfical difficulty. But though fome philofophers have undoubtedly been too liberal in recurring to it as the cause of every phenomenon that they could not otherwife account for; others, it now feems, have been too fparing and cautious in queftioning its prefence and agency, in certain phenomena which appeared to them to be repugnant to the known laws, by which the electric matter had hitherto been obferved to be regulated. In this laft clafs of circumfpect, but probably mistaken, reafoners, we include ourselves; and voluntarily take this opportunity of atoning for our error, by reminding our Readers of it, and acknowledging it.
In our Review of Dr. Priestley's Hiftory of Electricity, after obferving that the Author had wholly omitted, in that copious work, to take notice of the fuppofed electrical properties of the torpedo, gymnotus, or anguille tremblante, we clofed a fhort abftract which we gave of the uncircumftantial, and, to us, unfatisfactory accounts that had been received from Surinam concerning it, by expreffing our incredulity with regard to its elec tric qualities; founding our opinion on fome of the circumftances attending the fhock given by this fish, which to us ap peared to be incompatible with the principles of electricity.But in philofophical as well as in other matters, it feems, la verité n'eft pas toujours du coté de la vrayfemblance.-Truth and probability do not conftantly go together.
In our 37th volume, December 1767, page 453.
The experiments related in the first of these articles were made partly at the ifle of Ré, and partly at Rochelle, in the prefence of the members of the Royal Academy of Sciences at that place. They were conducted in a scientific manner, and properly diversified, with a particular view to discover the identity or diverfity of the electric and torpedinal concuffions. The refult of the Author's experiments feems pretty fatisfactorily to eftablish the torpedo in the rank of an electrician, furnished with a power over the electric matter; by means of which he can, without any foreign machinery, and almoft in an inftantaneous manner, collect, condenfe, and at his will difpenfe it to neighbouring bodies, through any of thofe fubftances that are known to be conductors of the electric fluid.
The identity of the concuffions given in the common electrical experiments, and by the torpedo, feems to be fully ascertained by the following facts and obfervations, which we shall collect from different parts of this article. To render our ac count intelligible, we fhall premife that the torpedo is a flat fifh; and that from Mr. Hunter's accurate anatomical description of it, accompanied with two excellent drawings, it ap pears that the very confpicuous organs, by which it undoubt edly exerts its fingular powers, confift of a congeries of cylinders, or rather hexagonal columns, placed clofe and parallel to each other, and extending from the breaft, on both fides, perpendicularly upwards, to the back of the animal; suppofing it to lie on its breaft, or in a horizontal pofition.
It had before been obferved that the fenfation attending the action of the torpedo was perfectly fimilar to that which accompanied the concuffion produced on the discharge of the Leyden vial. In order to receive a fhock from the torpedo, it is now likewife found to be requifite, that a metallic or other proper line of communication fhould be formed, between the breaft and the back of the animal, or between the oppofite furfaces of, what are here called, the electric organs; in the fame manner, and formed of the fame conducting materials, that are neceffary to convey the electric fhock, on forming a circuit between the infide and outfide furfaces of the Leyden vial. We fhall illuftrate this fimilarity by an example.
One extremity of an infulated wire, 13 feet long, being in contact with the breaft of the fifh, lying on a table, the other end was immersed in a bason of water, into which a person put a finger of one hand, while he plunged a finger of the other hand into fome water contained in another bafon. Four, and fometimes feven, more perfons extended the line, not by joining hands, but by dipping a finger of each hand into a bafon of water placed between each of them. In the laft bafon, one extremity of another wire, 13 feet long, was immerfed, while
its other end was laid hold of by Mr. Walsh, and brought in contact with the back of the torpedo. All the eight, who were in the line, felt commotions fimilar to that given by the Leyden vial; while Mr. Walth, who only prefented the wire, and was not within the circuit, was not affected.
Thus it is evident that the action of the torpedo is communicated through metals and water, or, in general, through the fame media that tranfmit the electrical concuffion. It follows likewife that the upper and under parts of the animal, like the upper and under furfaces of an electrified plate of glafs, are in different ftates: for a perfon who touches only the upper or the under furfaces of the electric organs will not receive the torpedinal concuffion. Further, thofe fubftances that will not conduct the electric matter, as glass, fealing wax, &c. were found equally to intercept the action of the torpedo.
This action evidently depends on the will of the animal, who however scarce exhibits any other fenfible motion or effort at the time of exerting it, than a depreffion or winking of his eyes. This motion is obferved likewife to accompany his fruitless attempts to tranfmit a fhock through non-conductors. The stock of elec trical or other matter which the torpedo poffeffes, appears to be very confiderable. A torpedo, when infulated, has given to Mr. Walsh, infulated likewise, no less than 50 fhocks in the space of a minute and a half.
We have hitherto recited only fome of the operations of the torpedo that are performed when he is in air. When a large. fifh, very liberal of his fhocks, was held in water, with one hand on his breast, and another on his back, he gave the operator fhocks of the fame kind as before; but, as near as could be estimated, they were about one-fourth only of the ftrength of thofe which he gave in air. At the very instant of raifing him out of the water, he conftantly gave a very violent fhock; and another nearly as violent when his lower furface firft touched the water on dipping him into it. On brifkly and alternately plunging him a foot deep into water, and raising him an equal height into air, befides one or two shocks which he difpenfed during the fhort time he was wholly in the water, and those which he gave at the furface, he conftantly difpenfed at least two when he was wholly in air: fo that Mr. Walsh eftimates that he gave above 100 fhocks during the minute that the experiment lafted.
This exertion of the powers of the torpedo in fo conducting a medium as water, exhibits a modification of the electric matter, diffimilar, and even contrary, to any of the forms which the latter has hitherto ever been obferved to affume. It must not be diffembled likewife that Mr. Waith, in all his numerous experiments, could never perceive that the torpedinal fluid was capable of
forcing its way through the minutest lamina or portion of air fo as to jump, for inftance, from one link of a small chain, fufpended freely, to another; or even to, país over an almoft imperceptible interval or flit formed by cutting through a flip of tinfoil patted on fealing wax, which conftituted part of the circuit. Under thefe circumftances no fpark could ever be perceived, even in the most complete darknefs; nor was any snapping ever head; nor could any attractions or repulfians of the pith balls be obferved during thefe experiments.-All these difficulties, excepting the firft, Mr. Walsh very ingeniously attempts to folve, fomewhat in the following manner:
With respect to the pith balls particularly, he observes that it is not surprising that no motion could be difcovered in them, as all his experiments fully fhewed that here was no gradual accumulation of the electric fluid, as in the cafe of charged glafs but that it was collected or condensed in the very intant of the explofion, by a fudden energy of the animal. He explains likewife this and the other differences between the phenomena of the Leyden vial and of the torpedo, or the abfence of light and found in the experiments made with the latter, by the following confiderations:
In a large fifh, the number of the cylinders or columns abovementioned, contained in one electric organ, was found to be no lefs than 1182. This immenfe collection of cylinders Mr. Walsh confiders as fomewhat analogous to a large number of jars in an electric battery, and as containing a very large area in confequence of the great number, and extenfive furface, of the columns. Now it is known, from experiments made with artificial electricity, that though the electric matter violently condenfed or crowded into a very fmall vial highly charged, is capable of forcing a paffage through an inch of air, and that it will afford, in a very confpicuous manner, the phenomena of light, found, attraction, and repulfion,-yet if the quantity thus condenfed be expanded and rarefied, by communicating it to, or dividing it among ft, a large number of jars, whofe coated furfaces conftitute a fpace, for inftance, 400 times larger than that of the vial ;-this identical quantity of electric matter, thus dilated, will now yield only the fainter, or, if the expreffion may be allowed, the negative phenomena of the torpedo. It will not now be capable of paffing over the 100th part of that inch of air, which, in its condensed state, it before sprung through with eafe: it will not now be able to jump over the little gap made in its track, by cutting through the tinfoil: no fpark, found, or attraction of light bodies, will now be perceived and yet this portion of electric matter, in this dilated ftate, and with its elafticity thus diminished, will, like that of the torpedo, to effect its equilibrium, run through a confider