raising a smoke from dry resin dropped into a hot tea-spoon under the electrized body, which will be attracted and spread itself equally on all sides, covering and concealing the body. And this form it takes, because it is attracted by all parts of the surface of the body, though it cannot enter the substance already replete. Without this attraction it would not remain round the body, but be dissi. pated in the air. The atmosphere of electrical particles surround. ing an electrified sphere is not more disposed to leave it, or more easily drawn off from any one part of the sphere than from another, because it is equally attracted by every part. But that is not the case with bodies of any other figure. From a cube it is more easily drawn at the corners than at the plane sides, and so from the angles of a body of any other form, and still most easily from the angle that is most acute; and for this reason points have a property of drawing on, as well as throwing off the electrical fluid, at greater distances than blunt bodies can.

From various experiments recited in our author's treatise, the preceding observations are deduced. And the following are a few of the other most singular ones. The effects of lightning, and those of electricity, appear very similar. Lightning has often been known to strike people blind. A pigeon, struck dead to appear. ance by the electrical shock, recovering life, drooped several days, ate nothing, though crumbs were thrown to it, but declined and died. Mr. F. did not think of its being deprived of sight; but afterwards a pullet, struck dead in like manner, being recovered by repeatedly blowing into its lungs, when set down on the floor, ran headlong against the wall, and on examination appeared per. fectly blind; hence he concluded that the pigeon also had been absolutely blinded by the shock. From this observation we should be extremely cautious, how in electrizing we draw the strokes, especially in making the experiment of Leyden, from the eyes, or even from the parts near them.

Some time since it was imagined, that deafness had been relieved Dylectrizing the patient, by drawing the snaps from the ears, and by making him undergo the electrical commotion in the same man. ner. If hereafter this remedy should be fantastically applied to the eyes in this manner to restore dimness of sight, it will be well if perfect blindness be not the consequence of the experiment.

By a very ingenious experiment our author endeavours to evince

the impossibility of success, in the experiments proposed by others of drawing forth the effluvia of non-electrics, cinnamon, for in. stance, and by mixing them with the electrical fluid, to convey them with that into a person electrified; and our author thinks, that, though the effluvia of cinnamon and the electrical fluid should mix within the globe, they would never come out together through the pores of the glass, and thus be conveyed to the prime conduc. tor; for he thinks, that the electrical fluid itself cannot come through, and that the prime conductor is always supplied from the cushion, and this last from the floor. Besides, when the globe is filled with cinnamon, or other non-electrics, no electricity can be obtained from its outer surface, for the reasons before laid down. He has tried another way, which he thought more likely to obtain a mixture of the electrical and other effluvia together, if such a mixture had been possible. He placed a glass plate under his cushion, to cut off the communication between the cushion and the floor; he then brought a small chain from the cushion into a glass of oil of turpentine, and carried another chain from the oil of tur. pentine to the floor, taking care that the chain from the cushion to the glass touched no part of the frame of the machine. Another chain was fixed to the prime conductor, and held in the hand of a person to be electrified. The ends of the two chains in the glass were near an inch from each other, the oil of turpentine between. Now the globe being turned could draw no fire from the floor through the machine, the communication that way being cut off by the thick glass plate under the cushion: it must then draw it through the chains, whose ends were dipped in the oil of turpentine. And as the oil of turpentine, being in some degree an electric per se, would not conduct what came up from the floor, the electri. city was obliged to jump from the end of one chain to the end of the other, which he could see in large sparks; and thus it had a fair opportunity of seizing of the finest particles of the oil in its passage, and carrying them off with it; but no such effect fol. lowed, nor could he perceive the least difference in the smell of the electrical effluvia thus collected, from what it had when collected otherwise; nor does it otherwise affect the body of the person elec trified. He likewise put into a phial, instead of water, a strong purging liquid, and then charged the phial, and took repeated shocks from it; in which case every particle of the electrical fluid

must, before it went through his body, have first gone through the liquid, when the phial is charging, and returned through it when discharging; yet no other effect followed than if the phial had been charged with water. He had also smelt the electrical fire, when drawn through gold, silver, copper, lead, iron, wood, and the human body, and could perceive no difference; the odour being always the same, where the spark does not burn what it strikes ; and therefore he imagines, that it does not take that smell from any quality of the bodies it passes through.

Mr. Franklin, in a letter to Mr. Collinson some time since, men. tioned his intending to try the power of a very strong electrical shock on a turkey. He accordingly has been so obliging as to send an account of it, which is to the following purpose. He made first several experiments on fowls, and found, that two large thin glass jars gilt, holding each about six gallons, were sufficient, when fully charged, to kill common hens outright; but the turkeys, though thrown into violent convulsions, and then lying as dead for some minutes, would recover in less than a quarter of an hour. However, having added three other such to the former two, though not fully charged, he killed a turkey of about 10 lb. weight, and believes that they would have killed a much larger. He conceited, that the birds killed in this manner eat uncommonly tender.

In making these experiments, he found that a man could, with out great detriment, bear a much greater shock than he imagined; for he inadvertently received the stroke of two of these jars through his arms and body, when they were very near fully charged. It seemed to him an universal blow throughout the body from head to foot, and was followed by a violent quick trembling in the trunk, which went gradually off in a few seconds. It was some minutes before he could recollect his thoughts, so as to know what was the matter; for he did not see the flash, though his eye was on the spot of the prime conductor, from whence it struck the back of his hand; nor did he hear the crack, though the bystanders said, it was a loud . one; nor did he particularly feel the stroke on his hand, though he afterwards found that it had raised a swelling there the size of a swan-shot or pistol-bullet. His arms and the back of his neck felt somewhat numbed the remainder of the evening, and his breast was sore for a week after, as if it had been bruised. From this expe riment may be seen the danger, even under the greatest caution, to

COMMUNICATION & VELOCITY OF ELECTRICITY.

275

the operator, when making these experiments with large jars; for it is not to be doubted, but that several of these fully charged would as certainly, by increasing them, in proportion to the size, kill a man, as they did before the turkey.

SECTION 11.

[Phil. Trans. 1751.

1. Communication and velocity of Electricity.

By W. Watson, Esq.

In a former paper Mr. W. took notice, that among the many surprising properties of electricity, none was more remarkable, than that the electrical power, accumulated in any non-electric matter contained in a glass phial, described on its explosion a cir. cuit through any line of substances non-electrical in a considerable degree; if one end of it was in contact with the external surface of this phial, and the other end on the explosion touched either the electrified gun barrel, to which the phial in charging was usually connected, or the iron hook always fitted in it. This circuit, where the non-electric substances, which happen to be between the outside of the phial and its hook, conduct electricity equally well, is always described in the shortest route possible; but if they conduct differently, this circuit is always formed through the best. conductor, how great soever its length is, rather than through one which conducts not so well, though of much less extent.

It has been found, that in proportion as bodies are susceptible of having electricity excited in them by friction, in that proportion. they are less fit to conduct it to the other bodies; in consequence, of all the substances we are acquainted with, metals conduct best the electrical powers; for which reason the circuit before spoken Water likewise is an of is formed through them the most readily. excellent conductor; for the electrical power makes no difference between solids and fluids as such, but only as they are non-electric

matter.

Mons. le Monnier the younger, at Paris, in an account transmitted to the Royal Society, takes notice of his feeling the stroke of the electrified phial along the water of two of the basins of the Thuilleries, the surface of one of which is about an acre, by means

of an iron chain which lay on the ground, and was stretched round half their circumference. On these considerations it was conjec tured, as no circuit had as yet been found large enough so to dis sipate the electrical power as not to make it perceptible, that if the non-electrical conductors were properly disposed, an observer might be made sensible of the electrical commotion quite across the river Thames, by the communication of no other medium than the water of that river. In any other part of natural philosophy, as we should draw conclusions only from the facts themselves, it was determined to make the experiment.

The making this experiment drew on many others, and as the gentlemen concerned flatter themselves that they were made with some degree of attention and accuracy, they thought it not improper to lay a detail of all the operations before the Royal Society. To try this experiment, it was absolutely necessary that a line of non-electric matter, equal in length to the breadth of the river, should be laid over it, so as not to touch the water in any part of its length; and the bridge of Westminster was thought the most proper for that purpose, where the water from shore to shore was somewhat more that four hundred yards.

Accordingly on July 14, 1747, several members of the Royal Society met to assist in making the experiment. A line of wire laid along the bridge, not only through its whole length, but likewise turning at the abutments, reached down the stone steps on each side of the river low enough for an observer to dip into the water an iron rod held in his hand. One of the company then stood on the steps of the Westminster shore, holding this wire in his left hand, and an iron rod touching the water in his right; on the steps facing the former on the Surry shore, another of the company took hold of the wire with his right hand, and grasped with his left a large phial almost filled with filings of iron, coated with sheet-lead, and highly electrified by a glass globe properly disposed in a neigh. bouring house. Athird observer standing near the second dipped an iron rod held in his left hand into the water, and touching the iron hook of the charged phial with a finger of his right hand, the electricity snapped, and its commotion was felt by all the three observers, but much more by those on the Surry shore. The third observer here was no otherwise necessary, than that the river being full, the iron was not long enough to be fixed in the mud on