de cet événement dans toutes les occasions. | by wetting the apparatus, the electricity was Coiffier a été le premier qui a fait l'expéri- dissipated too soon to be perceived upon ence et l'a répétée plusieurs fois; ce n'est qu'à l'occasion de ce qu'il a vu qu'il m'a envoyé prier de venir. S'il étoit besoin d'autres temoins que de lui et de moi, vous les trouveriez. Coiffier presse pour partir.

only ones, that the last summer here has produced; and as they were made by persons worthy of credit, they tend to establish the authenticity of those transmitted from our correspondents.

I flatter myself, that this short account of these matters will not be disagreeable to you; and am, W. WATSON.*

COLDENHAM, in New York, Dec. 4, 1753.

ger 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 from 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 sur

Remarks on the Abbé Nollet's Letters to Ben-face from the conductor. If it be only drawn jamin Franklin, of Philadelphia, on elec-out by sparks, a vast number of them may tricity: by David Colden, of New York. 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 capa IN considering the Abbé Nollet's Letters ble of, and the outside will then be entirely to Mr. Franklin, I am obliged to pass by all destitute of its electric matter, and no spark the experiments which are made with, or in, can be drawn from it by the finger: here then bottles hermetically sealed, or exhausted of is a want of that effect, which all bodies chargair; because, not being able to repeat the ex-ed with electricity have. Some of the effects periments, I could not second any thing which of an electric body, which I suppose the Abbe occurs to me thereon, by experimental proof. has observed in the exterior surface of a Wherefore, the first point wherein I can dare charged phial, are, that all light bodies are atto give my opinion, is in the Abbé's 4th tracted by it. This is an effect which I have letter, where he undertakes to prove, that constantly observed, but do not think that it the electric matter passes from one surface to proceeds from an attractive quality in the exanother through the entire thickness of the terior surface of the phial, but in those light glass: he takes Mr. Franklin's experiment of bodies themselves, which seem to be attractthe magical picture, and writes thus of it: ed by the phial. It is a constant observation, "When you electrise a pane of glass coated that when one body has a greater charge of on both sides with metal, it is evident that electric matter in it than another (that is in whatever is placed on the side opposite to proportion to the quantity they will hold) this that which receives the electricity from the body will attract that which has less now, I conductor, receives also an evident electrical suppose, and it is a part of Mr. Franklin's virtue." Which Mr. Franklin says, is that system, that all those light bodies which apequal quantity of electric matter, driven out pear to be attracted, have more electric matof this side, by what is received from the con- ter in them than the external surface of the ductor on the other side; and which will con- phial has, wherefore they endeavour to attinue to give an electrical virtue to any thing tract the phial to them, which is too heavy to in contact with it, till it is entirely discharg- be moved by the small degree of force they ed of its electrical fire. To which the Abbé exert, and yet being greater than their own thus objects: "Tell me (says he,) I pray you, weight, moves them to the phial. The folhow much time is necessary for this pretend-lowing experiment will help the imagination ed discharge? I can assure you, that after having maintained the electrisation 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 electrised 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 effects 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 fin

*This is the sometime celebrated Watson, bishop of

Landaff

in conceiving this. Suspend a cork ball, or a feather, by a silk thread, and electrise 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, "that he can electrise 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 give; neither can it give as much to the part of the conductor, which I take to be the coating of the other phial as it is ready to take certainest sign that the phial has received all when one is only applied to me: but when the electric matter it can: after this appears, both are applied, the coating takes from me let the man, who before stood on the floor, what the hook gives: thus I receive the fire step on a cake of wax, where he may stand from the first phial at B, the exterior surface for hours, and the globe all that time turned, of which is supplied from the hand at A; I and yet have no appearance of being elec- give the fire to the second phial at C, whose trised. After the electric matter was spewed interior surface is discharged by the hand at out as above from the hook of the phial pre- D. This discharge at D may be made evipared for the Leyden experiment, I hung ano- dent by receiving that fire into the hook of a ther phial, in like manner prepared, to a hook third phial, which is done thus: in place of fixed in the coating of the first, and held this taking the hook of the second phial in your other phial in my hand; now if there was hand, run the wire of a third phial, prepared any electric matter transmitted through the as for the Leyden experiment, through it, and glass of the first phial, the second one would hold this third phial in your hand, the second certainly receive and collect it; but having one hanging to it, by the ends of the hooks kept the phials in this situation for a consi-run through each other: when the experiderable time, during which the globe was con- ment is performed, this third phial receives tinually turned, I could not perceive that the the fire at D, and will be charged. 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 his 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 themselves one on each side of me, while I stood on a cake of wax, and took hold of the hook of that phial which was held by its coating (upon which a spark issued, but the phial was not discharged, as I stood on wax) keeping hold of the hook, I touched the coating of the phial that was held by its hook with my other hand, upon which there was a large spark to be seen between my finger and the coating, and both phials were instantly discharged. If the Abbé's opinion be right, that the exterior surface, communicating with the coating, is charged, as well as the interior, communicating with the hook; how can I, who stand on wax, discharge both these phials, when it is well known I could not discharge one of them singly? Nay, suppose I have drawn the electric matter from both of them, what becomes of it? For I appear to have no additional quantity in me when the experiment is over, and I have not stirred off the wax: wherefore this experiment fully convinces me, that the exterior surface is not charged; and not only so, but that it wants as much electric matter as the inner has of excess for by this supposition, which is a part of Mr. Franklin's system, the above experiment is easily accounted for, as follows: When I stand on wax, my body is not capable of receiving all the electric matter from the hook of one phial, which it is ready to

B

1

D

2

When this experiment is considered, I think, it must fully prove that the exterior surface of a charged phial wants electric matter, while the inner surface has an excess of it. One thing more worthy of notice in this experiment is, that I feel no commotion or shock in my arms, though so great a quantity of electric matter passes them instantaneously. I only feel a pricking in the ends of my fingers. This makes me think the Abbé has mistook, when he says, that there is no difference between the shock felt in performing the Leyden experiment, and the pricking felt on drawing simple sparks, except that of greater to less. In the last experiment, as much electric matter went through my arms, as would have given me a very sensible shock, had there been an immediate communication, by my arms, from the hook to the coating of the same phial; because when it was taken into a third phial, and that phial discharged singly through my arms, it gave me a sensible shock. If these experiments prove that the electric matter does not pass through the entire thickness of the glass, it is a necessary consequence that it must always come out where it entered.

The next thing I meet with is in the Abbé's fifth letter, where he differs from Mr.

in the same proportion that the other is filled: though this from experiment appears evident, yet it is still a mystery not to be accounted for.

Franklin, who thinks that the whole power retained by the glass. If after the spark is of giving a shock is in the glass itself, and not drawn from the conductor, you touch the in the non-electrics in contact with it. The coating of the phial (which all this while is experiments which Mr. Franklin gave to prove supposed to hang in the air, free from any this opinion, in his Observations on the Ley- non-electric body) the threads on the conductden Bottle, convinced me that he was in the or will instantly start up, and show that the right; and what the Abbé has asserted, in con- conductor is electrised. It receives this electradiction thereto, has not made me think trisation from the inner surface of the phial, otherwise. The Abbé, perceiving as I sup- which, when the outer surface can receive pose, that the experiments, as Mr. Franklin what it wants from the hand applied to it, had performed them, must prove his assertion, will give as much as the bodies in contact with alters them without giving any reason for it, it can receive, or if they be large enough, all and makes them in a manner that proves no- that it has of excess. It is diverting to see thing. Why will he have the phial, into how the threads will rise and fall by touching which the water is to be decanted from a the coating and conductor of the phial altercharged phial, held in a man's hand? If the nately. May it not be that the difference bepower of giving a shock is in the water con- tween the charged side of the glass, and the tained in the phial, it should remain there outer or emptied side, being lessened by though decanted into another phial, since no touching the hook or the conductor; the outer non-electric body touched it to take that power side can receive from the hand which touchoff. The phial being placed on wax is no ob- ed it, and by its receiving, the inner side canjection, for it cannot take the power from the not retain so much; and for that reason so water, if it had any, but it is a necessary much as it cannot contain electrises the wameans to try the fact; whereas, that phial's ter, or filings and conductor; for it seems to being charged when held in a man's hand, be a rule, that the one side must be emptied only proves that water will conduct the electric matter. The Abbé owns, that he had heard this remarked, but says, why is not a conductor of electricity an electric subject? This is not the question; Mr. Franklin never I am in many places of the Abbé's book sursaid that water was not an electric subject; prised to find that experiments have succeeded he said, that the power of giving a shock was so differently at Paris, from what they did in the glass, and not in the water; and this, with Mr. Franklin, and as I have always obhis experiments fully prove; so fully, that it served them to do. The Abbé, in making exmay appear impertinent to offer any more; periments to find the difference between the yet as I do not know that the following has two surfaces of a charged glass, will not have been taken notice of by any body before, my the phial placed on wax: for, says he, dont inserting of it in this place may be excused. you know that being placed on a body origiIt is this: hang a phial, prepared for the Ley-nally electric, it quickly loses its virtue? I den experiment, to the conductor, by its hook, and charge it; which done, remove the communication from the bottom of the phial: now the conductor shows evident signs of being electrised; for if a thread be tied round it, and its ends left about two inches long, they will extend themselves out like a pair of horns; but if you touch the conductor, a spark will issue from it, and the threads will fall, nor does the conductor show the least sign of being electrised after this is done. I think that by this touch, I have taken out all the charge of electric matter that was in the conductor, the hook of the phial, and water or filings of iron contained in it; which is no more than we see all non-electric bodies will receive: yet, the glass of the phial retains its power of giving a shock, as any one will find that pleases to try. This experiment fully evinces, that the water in the phial contains no more electric matter than it would do in an open bason, and has not any of that great quantity which produces the shock, and is only

* See pages 246 to 249, of this volume.

cannot imagine what should have made the Abbé think so: it certainly is contradictory to the notions commonly received of electrics per se; and by experiment I find it entirely otherwise: for having several times left a charged phial, for that purpose, standing on wax for hours, I found it to retain as much of its charge as another that stood at the same time on a table. I left one standing on wax from ten o'clock at night till eight the next morning, when I found it retain a sufficient quantity of its charge, to give me a sensible commotion in my arms, though the room in which the phial stood had been swept in that time, which must have raised much dust to facilitate the discharge of the phial.

I find that a cork-ball suspended between two bottles, the one fully and the other but little charged, will not play between them, but is driven into a situation that makes a triangle with the hook of the phials: though the Abbé has asserted the contrary of this, in order to account for the playing of a corkball between the wire thrust into the phial, and one that rises up from its coating. The

Relating a curious Instance of the Effect of Oil Others, more deeply skilled in those princi

was taken up with oil; the rest was left thy clergyman at Carlisle, whose great learn