the shore, and therefore was in want of some support. The expe. riment was repeated several times, both then and afterwards, and electrical motion felt across the river. The length of this circuit, through which the electricity was propagated, was at least eight hundred yards, more than four hundred yards of which was formed by the stream of the river.

The observers on the Westminster shore not feeling the electrical the commotion equally strong with those of Surry, was judged to proceed from other causes besides that of distance. For it must be considered, that the conducting wire was almost throughout its whole length laid on Portland stone standing in water. This stone being in a great degree non-electric, is of itselfa conductor of electricity; and this stone standing in water, no more of the electricity was transmitted to the observers on the Westminster shore than that proportion, on which iron is more non-electric, and consequently a better conductor of electricity than stone. Whether the conducting wire on the bridge was broken or no, and, conse quently, whether the observers on the Westminster shore felt the electrical commotion or no, not only the observers on the Surry shore, who with their wire formed part of the line, felt the shock in their arms; but those persons who only stood on the stone steps there, and touched the wire with their fingers, felt the elec trical commotion in the arm of that hand which touched the wire. Hence, and from a person feeling the electrical commotion stand. ing on the wet stone steps of the Westminster shore, though not forming part of the line, but only touching the wire with his fin. gers, it was concluded, that besides the large circuit before spoken of, there were formed several other subordinate circuits, between the same steps of the Surry shore, and the bridge by means of the water; by which that part of the electrical power, felt by the ob servers on the Surry side of the river, and not by those on the Westminster side, was discharged.

Dr. Bevis having observed, that which was likewise tried here, that however well an electrified phial was charged, its iron hook would not fire the vapours of warm spirits of wine held in a spoon and applied to it, if the person who held the phial, and who held the spoon, did not take each other by the hand, or have some other non-electrical communication between them; it was there. fore thought proper to try the effects of electricity on some warm

spirit of wine through the large circuit before mentioned. Ac. cordingly the observers being placed as before, both on the Westminster and Surry shores, no other alteration was made in the beføre mentioned apparatus, than that the wire which connected the gun-barrel with the iron hook of the coated phial being laid aside, the coated phial itself was charged at the gun-barrel, and then brought in the hands of an observer near the warm spirits in the spoon, which was placed on the short iron rod beforementioned, which was connected with the wire which went to the observers on the Surry shore. On presenting properly the iron hook of the charged phial to the warm spirit, it was instantly fired, and the elec cal commotion felt by the observers on both sides of the river.

It was then thought proper to try the effects of the charged phial on the warm spirit, when the wire was divided which was laid over the bridge; on presenting the iron hook to the spirit, a sufficient snap was given to the spoon to fire the spirit, but nothing so smart as in the former experiment where the large circuit was completed.

It was then tried what effect would be on the spirit, if the charged phial was divested of its long wire which lay over the bridge, and was only held in the hand of an observer; while the spoon with warm spirit was placed in contact of the iron rod beforemen. tioned, to which the wire was connected, which went to the obser vers on the Surry shore; and the spirit was fired with much the same degree of smartness as in the last experiment.

In these and all the subsequent operations, wires were made use of to conduct the electricity preferable to chains, as by great numbers of experiments it had been fully proved, that whatever difference there was in the bulk of the conductor, viz. whether it were a small wire, or a thick iron bar, the electrical strokes communicated were equally strong; and it had been further observed, besides the difficulty of procuring chains of a requisite length for the present purposes, that the stroke at the gun-barrel, when the electricity was conducted by a chain, was cæteris paribus not so strong, as when that power was conducted by a wire. This was occasioned by the junctures of the links of the chain not being sufficiently close, which caused the electricity in its passage to snap and flash at the junctures, where there was the least separation; and these smaller snappings in the whole length of the chain lessened the great one of the gun-barrel.

Encouraged by the success of these trials, the gentlemen were desirous of continuing their inquiries, and of knowing whether the electrical commotions were perceptible at a still greater distance. The New River near Stoke Newington was thought most coveni. ent for that purpose; as at the bottom of that town, the windings of the river are such, that from a place which he calls A to another B, the distance by land is about eight hundred feet, but the course of the river is near two thousand. From A to another place C, in a right line is two thousand eight hundred feet, but the course of the water is near eight thousand feet.

Accordingly, on Friday July 24, 1747, there met at Stoke Newington the president of the Royal Society and several other gentlemen: when every being thing disposed as before, and the wire extended from A to B and C, over the meadow, without touching the water. When every thing was thus disposed, and the signals given, the charged phial was exploded several times, and the electrical commotion every time smartly felt by the observers both at A and B. In the like trials with the places A and C, the commotions were perceptible from A to C ; a distance not less than two thousand eight hundred feet by land, and near eight thousand by water.

To execute this, to the former wire, which was already conducted to B, another was added, which there crossed the river without touching the water; and reached almost to C, where the first of a line of gentlemen held as before the wire in one hand, and the last dipped the iron into the water. The wire from the ma. chine to A was as before. Its effects were plainly though but faintly perceived each time by some of the observers, but never by them all. The electrical commotion was always felt by that observer, who held the extremity of the wire, but never by him who held the iron rod in the water. It was in one experiment felt by the observer who held the wire, not felt by the next who held the hand of the former, and yet plainly perceived by the third who joined the second. Those who did not themselves feel the electrical commotion here, did as at B, see the involuntary motions of those who did. The observers at A felt the shocks in the same degree, whether the other observers were stationed at B or C.

This experiment further demonstrates the distance to which the electrical power may be conveyed: but the same difficulty occurs here as in the last, viz, whether the circuit was completed by the water of the river, or by the ground which was wet?

To resolve this doubt then, the gentlemen met again July 28, 1747: when the electrical commotion was first tried from A to B beforementioned, the iron wire in its whole length being supported, without any where touching the ground, by dry sticks placed at proper intervals, of about three feet in height. The observers both at A and B stood on originally-electrics, and, on the signal, dipped their iron rods into the water. On discharging the phial, which was several times done, they were both very much shocked, much more so than when the conducting wire lay on the ground, and the observers stood on it, as in the former experiments. The same experiment was tried with the observer at A, instead of the iron rod, dipping a narrow slab of Portland stone into the water of about three feet and a half in length; when the shock was felt, but not so severe as through the iron rod. This demonstrated, as was be. fore suggested, why the electrical commotion was not felt stronger by the observers on the western shore of Westminster bridge, viz. that Portland stone standing in water will conduct electricity very considerably.

The gentlemen then tried what would be the effect, if the observer at B stood on a cake of wax holding the wire as before, and touched the ground of the meadow with his iron rod at least a hundred and fifty feet from the water; and if the observer usually placed near the river at A, had his wire carried a hundred and fifty feet over the river as the former, stood on an originally-elec tric, and touched the ground with his iron rod. On the explosion of the charged phial, which was several times done, both the ob. servers were smartly struck. This demonstrated, that in these instances the moist ground of the meadows made part of the circuit. The observers were distant from each other about five hundred feet.

The observers then, stationed as in the last experiment, stood on the wax cakes as before, without touching the ground with the iron rods, or any part of their bodies, and the charged phial was exploded four times. These were not at all felt by the observer next to B, and without the greatest attention would not have been perceived by him next to A; and then only in some of the trials, the feeling of the electricity was like that of a small pulse between the finger and thumb of that hand which held the wire. The loaded phial was again discharged four times more, without any other al

teration in the disposition of the apparatus than that the observer next to B stood on the ground; when the electrical commotion was perceived by the observer, though not so sharp as when the other observer at the same time stood on the ground. The observer next to A felt the tingling between his finger and thumb as before.

The gentlemen were desirous of trying the electrical commotion at a still greater distance than any of the former through the water, and where, at the same time by altering the disposition of the apparatus, it might he tried whether that power would be perceptible through the dry ground only at a considerable distance. Highbury Barn beyond Islington was thought a convenient place for this purpose, as it was situated on a hill nearly in a line, and almost equi.distant from two stations on the New River, somewhat more than a mile asunder by land, though following the course of that river their distance from each other was two miles. The hill between these stations was of a gravelly soil; which, from the late continuance of hot weather without rain, was dry, full of cracks, and consequently was as proper to determine whether the electricity would be conducted by dry ground to any great dis tance, as could be desired. Accordingly, on Wednesday, August 5, 1747, they met at Highbury Barn. The electrifying machine being placed up one pair of the stairs in the house there, a wire from the coated phial was conducted on dry sticks as before to that station by the side of the New River, which was to the northward of the house. The length of this wire was three furlongs and six chains, or 2376 feet. Another wire fastened to the iron bar, with which, in making the explosion, the gun-barrel was touched, was conducted in like manner to the station on the New River to the southward of the house. The length of this wire was four furlongs five chains and two poles, or 3003 feet. The length of both wires, exclusive of their turnings round the sticks, was one mile one chain and two poles, or 5379 feet. For the more conveniently describing the experiments made here, we will call the station to the northward D, and the other E.

At this distance the gentlemen proposed to try, first, whether the electrical commotion was perceptible, if both the observers at D and E. supported by originally-electrics, touched the conducting wire with one band, and the water of the New River with an iron