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side it a greater portion of electricity than its natural share, and hold it in my hand, or place it on any conducting substance, as a table, a part of the electric fluid, that naturally belongs to the outside, will make its escape through my body, on the table.

Charles. Let me try this.

Tutor. But you must be careful that you do not break the glass.

Charles. I will hang the chain on the conductor, and let the other end lie on the bottom of the glass, and James will turn the machine.

Tutor. You must take care that the chain does not touch the edge of the glass, because when the electric fluid will, by that means, run from one side of it to the other, and spoil the experiment.

James. If I have turned the machine enough, take the chain out, and try the two sides with the insulated pith-ball.

Charles. What is this? Something has pierced through my arms and shoulders.

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Tutor. That is a trifling electrical shock, which you might have avoided, if you had waited for my directions.

Charles. Indeed it was not trifling: feel it now.

Tutor. This leads us to the Leyden phial: $0 called, because the discovery was first made at Leyden, in Holland, and by means of a phial or small bottle.

James. Was it found out in the same manner as Charles has just discoverd it?

Tutor. Nearly so. Mr. Cuneus, a Dutch philosopher, was holding a glass phial in his hand, about half filled with water, but the sides above the water, and the outside was quite dry, a wire also hung from the conductor of an electrical machine into the wa. ter.

James. Did that answer to the chain ?

Tutor. Just so : and, like Charles, he was going to disengage the wire with one hand, as he held the bottle in the other, and was surprised and alarmed by a sudden shock in his arms, and through his breast, which he had not the least expected.

Charles. I do not think there was any think to be alarmed at.

Tutor. The shock which he felt was, probably, something severer than that which you have just experienced: but the terror was evidently increased by its coming so completely unexpected.

When M. Muschenbroeck first felt the shock, which was by means of a thin glass bowl, and very slight, he wrote to M. Reaumur, that he felt himself struck in his arms, shoulders, and breast, so that he lost his breath, and was two whole days before he recovered from the effects of the blow.

Charles. Perhaps he meant the fright.

Tutor. Terror seems have been the effect of the shock: for he adds, “ I would not take a second shock, for the whole kingdom of France."

Mr. Ninkler, an experimental philosopher, at Leipsic, describes the shock as having gi. ven him convulsions, a heaviness in his head, such as he should feel if a large stone were on it, and he had reason to dread a fever, to prevent which he put himself on a course

of cooling medicines. “ Twice," says he, “ it gave me a bleeding at the nose, to which I am not inclined : and my wife, whose cu. riosity surpassed her fears, received the shock twice, and found herself so weak, that she could scarcely walk. Nevertheless, in the course of a few days, she received an. other shock, which caused a bleeding at the nose."

James. Is this called the Leyden phial?

Tutor. It is. They are now made in this manner (Plate vii. Fig. 6.) B A is a glass jar, both inside and out are covered with tin foil about three parts of the way up, as far as X.

Charles. Does the outside covering an. swer to the hand, and the inside covering to the water?

Tutor. They do. The piece of wood z is placed on the top, merely to support the brass wire and knob v, to the bottom of which hangs a chain that rests on the bottom of the jar. I will now set the jar in such a situation that it shall be within two or three

inches of the conductor, while I work the machine.

James. The sparks fly rapidly from the conductor to the knob v.

Tutor. By that means, the inside of the jar becomes charged with a superabundant quantity of electricity: and as it cannot contain this, without, at the same time, driving away an equal quantity from the outside, the inside is positively electrified, and the outside is negatively electrified. To restore to the equilibrium, I must make a communication between the outside and inside with some conducting substance. That is, I must make the same substance touch, at the same time, the outside tin foil, and that which is within, or, which is the same thing, another substance that does touch it.

Charles. The brass wire touches the inside: if I, therefore, with one hand touch the knob, and with the other the outside covering, will it be sufficient?

Tutor. It will: but I had rather you would not, because the shock will be more powerful than I should wish either myself VOL. III.

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