Remarks on the Abbé Nollet's Letters to Benjamin Franklin on Electricity. By David Colden, of New York.* SIR, Coldenham, in New York, 4 December, 1753. In considering the Abbé Nollet's letters to Mr. Franklin, I am obliged to pass by all the experiments which are made with, or in, bottles hermetically sealed, or exhausted of air; because, not being able to repeat the experiments, I could not second any thing which occurs * The Abbé Nollet published in Paris a volume entitled, “ Lettres sur l'Electricité, dans lesquelles on examine les Découvertes qui ont été faites sur cette Matière depuis l'Année 1752, et les Conséquences que l'on en peut tirer." These letters were directed to various persons. One volume only was published originally, but the work was afterwards extended to three. In the first volume were six letters directed to Franklin. The author, having formed a theory of his own on electricity, attempted to confute the doctrines and hypotheses of the American philosopher. The following is an extract from the preface to the edition of the Abbé Nollet's work published in 1764. "Le Livre de M. Franklin est devenu célèbre par le goût qu'on a pris aux expériences curieuses qu'il contient, et par les nouvelles merveilles qu'il nous a fait découvrir; cet ouvrage est entre les mains de tout le monde, et, la doctrine qu'il renferme étant par bien des endroits opposée à celle que j'ai enseignée jusqu'à présent sur les mêmes matières, si je n'en disois rien, mon silence pourroit passer pour un abandon que je ferois de mes opinions. Ne fût-ce qu'en reconnoissance de l'honneur que l'Académie des Sciences m'a fait de les insérer dans ses Mémoires, et de l'accueil favorable que le public a bien voulu leur faire, je me suis cru obligé de les examiner de nouveau, et d'en prendre la défense, quand j'ai vu que je le pouvois faire par de bonnes raisons et malgré les prétentions de l'Ecole de Philadelphie. Voilà encore ce qui a donné lieu aux Lettres que je publie aujourd'hui; elles doivent moins passer pour une critique de la doctrine de M. Franklin, que pour une défense de la mienne; cet auteur n'a commencé à écrire qu'après moi. "Ce n'est pas que je croie que M. Franklin ait eu dessein de me critiquer; il ne savoit peut-être pas que j'existois; mais, quand il auroit connu mes ouvrages, et qu'il les auroit eu en vue en écrivant le contraire de ce qu'ils contiennent, je ne lui en saurois pas plus mauvais gré, s'il a cru, comme je n'en doute pas, opposer des vérités à des erreurs. Au reste, je ne me suis point borné à disputer contre ce physicien; j'ai to me thereon, by experimental proof. Wherefore, the first point wherein I can dare to give my opinion, is in the Abbé's fourth Letter, (p. 66,) where he undertakes to prove, that the electric matter passes from one surface to another through the entire thickness of the glass. He takes Mr. Franklin's experiment of the magical picture, and writes thus of it. "When you electrize a pane of glass coated on both sides with metal, it is applaudi très-sincérement aux endroits de son ouvrage qui m'ont paru solidement établis, ou ingénieusement pensés, et c'est ce que j'ai fait avec le plus de plaisir." Franklin never answered the Abbé's book, though he says, in a letter to Mr. Bowdoin, that he had collected and methodized short hints for that purpose. And in his autobiography he thus speaks of the subject, after alluding to the publication of his papers on electricity. "A copy of them happening to fall into the hands of the Count de Buffon, (a philosopher deservedly of great reputation in France, and indeed all over Europe,) he prevailed with Monsieur Dubourg to translate them into French; and they were printed at Paris. The publication offended the Abbé Nollet, preceptor in Natural Philosophy to the royal family, and an able experimenter, who had formed and published a theory of electricity, which then had the general vogue. He could not at first believe that such a work came from America, and said it must have been fabricated by his enemies at Paris to oppose his system. Afterwards, having been assured that there really existed such a person as Franklin at Philadelphia, (which he had doubted,) he wrote and published a volume of Letters chiefly addressed to me, defending his theory, and denying the verity of my experiments, and of the positions deduced from them. I once purposed answering the Abbé, and actually began the answer; but, on consideration that my writings contained a description of experiments, which any one might repeat and verify; and, if not to be verified, could not be defended; or of observations offered as conjectures, and not delivered dogmatically, therefore not laying me under any obligation to defend them; and reflecting, that a dispute between two persons, written in different languages, might be lengthened greatly by mistranslations, and thence misconceptions of one another's meaning, (much of one of the Abbé's letters being founded on an error in the translation ;) I concluded to let my papers shift for themselves; believing it was better to spend what time I could spare from public business in making new experiments, than in disputing about those already made. I therefore never answered Monsieur Nollet; and the event gave me no cause to repent my silence; for my friend, Monsieur Le Roy, of the Royal Academy of Sciences, took up my cause and refuted him." David Colden was a son of Cadwallader Colden, and devoted to the study of electricity. - EDITOR. evident, that whatever is placed on the side opposite to that which receives the electricity from the conductor, receives also an evident electrical virtue." Which, Mr. Franklin says, is that equal quantity of electric matter, driven out of this side, by what is received from the conductor on the other side; and which will continue to give an electrical virtue to any thing in contact with it, till it is entirely discharged of its electrical fire. To which the Abbé thus objects; "Tell me," says he, (p. 68,) "I pray you, how much time is necessary for this pretended discharge? I can assure you, that, after having maintained the electrization for hours, this surface, which ought, as it seems to me, to be entirely discharged of its electrical matter, considering either the vast number of sparks that were drawn from it, or the time that this matter had been exposed to the action of the expulsive cause; this surface, I say, appeared rather better electrized thereby, and more proper to produce all the effects of an actual electric body." The Abbé does not tell us what those effects were; all the effect I could never observe, and those that are to be observed can easily be accounted for, by supposing that side to be entirely destitute of electric matter. The most sensible effect of a body charged with electricity is, that, when you present your finger to it, a spark will issue from it to your finger; now, when a phial prepared for the Leyden experiment is hung to the gun-barrel or prime conductor, and you turn the globe in order to charge it, as soon as the electric matter is excited, you can observe a spark to issue fron the external surface of the phial to your finger, which, Mr. Franklin says, is the natural electric matter of the glass, driven out by that received by the inner surface from the conductor. If it be only drawn out by sparks, a vast number of them may be drawn; but, if you take hold of the external surface with your hand, the phial will soon receive all the electric matter it is capable of, and the outside will then be entirely destitute of its electric matter, and no spark can be drawn from it by the finger; here, then, is a want of that effect which all bodies charged with the electricity have. Some of the effects of an electric body, which I suppose the I. Abbé has observed in the exterior surface of a charged phial are, that all light bodies are attracted by it. This is an effect which I have constantly observed, but do not think that it proceeds from an attractive quality in the exterior surface of the phial, but in those light bodies themselves, which seem to be attracted by the phial. It is a constant observation, that, when one body has a greater charge of electric matter in it than another (that is, in proportion to the quantity they will hold), this body will attract that which has less; now, I suppose, and it is a part of Mr. Franklin's system, that all those light bodies, which appear to be attracted, have more electric matter in them than the external surface of the phial has; wherefore they endeavour to attract the phial to them, which is too heavy to be moved by the small degree of force they exert, and yet, being greater than their own weight, moves them to the phial. The following experiment will help the imagination in conceiving this. Suspend a cork ball, or a feather, by a silk thread, and electrize it; then bring this ball nigh to any fixed body, and it will appear to be attracted by that body, for it will fly to it; now, by the consent of electricians, the attractive cause is in the ball itself, and not in the fixed body to which it flies; this is a similar case with the apparent attraction of light bodies, to the external surface of a charged phial. The Abbé says, (p. 69,) "that he can electrize a hundred men, standing on wax, if they hold hands, and if one of them touch one of these surfaces (the exterior) with the end of his finger." This I know he can, while the phial is charging; but, after the phial is charged, I am as certain he cannot ; that is, hang a phial, prepared for the Leyden experiment, to the conductor, and let a man, standing on the floor, touch the coating with his finger, while the globe is turned, till the electric matter spews out of the hook of the phial, or some part of the conductor, which I take to be the certainest sign that the phial has received all the electric matter it can ; after this appears, let the man, who before stood on the floor, step on a cake of wax, where he may stand for hours, and the globe all that time turned, and yet have no appear ince of being electrized. After the electric matter was spewed out as above from the hook of the phial prepared for the Leyden experiment, I hung another phial, in like manner prepared, to a hook fixed in the coating of the first, and held this other phial in my hand; now, if there was any electric matter transmitted through the glass of the first phial, the second one would certainly receive and collect it; but, having kept the phials in this situation for a considerable time, during which the globe was continually turned, I could not perceive that the second phial was in the least charged, for, when I touched the hook with my finger, as in the Leyden experiment, I did not feel the least commotion, nor perceive any spark to issue from the hook. I likewise made the following experiment; having charged two phials (prepared for the Leyden experiment) through their hooks, two persons took each one of these phials in their hand; one held his phial by the coating, the other by the hook, which he could do by removing the communication from the bottom before he took hold of the hook. These persons placed them |
