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CONVERSATION XXVII.

INTRODUCTION.

The early History of Electricity.

TUTOR. If I rub pretty briskly with my hand this stick of sealing-wax, and then hold It near any small light substances, as little pieces of paper, the wax will attract them; that is, if the wax be held within an inch or more of the paper, they will jump up, and adhere to it.

Charles. They do; and I think I have heard you call this the effects of electricity, but I do not know what electricity is.

Tutor. It is the case with this part of science as with many others, we know it only by the effects which it produces. As I have not hitherto, in these conversations, attempted to bewilder your minds with useless theories, neither shall I, in the present case, attempt to say what the electrical fluid is : its action is well known; it seems diffused over every portion of matter with which we are acquainted, and, by the use of proper methods, it is as easily collected from surrounding bodies as water is taken from a river.

James. I see no fluid attaching to the sealing-wax when you have rubbed it. Tutor. You do not see the air which

you breathe, and with which you are surrounded, yet we have shown you* that it is a fluid, and may be taken from any vessel, as certainly, though not with so much ease, as water may be poured from this glass. With the exercise of a small degree of patience, you shall

* See Vol. II.

see such experiments as will not fail to convince you that their is as certainly a fluid, which is called the electric fluid, as there are such fluids as water and air.

Charles. Water must have been known since the creation, and the existence of the air could not long remain a secret, but who discovered the electric fluid, which is not at all evident to the sense either of sight or feeling?

Tutor. Thales, who lived six centuries before the Christian æra, was the first who observed the electrical properties of amber, and he was so struck with the appearances, that he supposed it to be animated :

Bright amber shines on his electric throne,
And adds ethereal lustre to his own.

DARWIN.

James. Does amber attract light bodies like sealing-wax?

Tutor. Yes, it does; and there are many other substances, as well as these, that have the same power. After Thales, the first person we read of that noticed this subject

was Theophrastus, who discovered that tourmalin has the power of attracting light bodies. It does not, however, appear that the subject, though very curious, excited much attention till about 200 years ago, when Dr. Gilbert, an English physician, examined a great variety of substances, with a view of ascertaining how far they might or might not be ranked among electrics.

Charles. What is meant by an electric?

Tutor. Any substance being excited or rubbed by the hand, or by a wooden cloth, or other means, and has the power of attracting light bodies, is called an electric.

James. Is not electricity accompanied with a peculiar kind of light, and with sparks?

Tutor. It is, of which we shall speak more at large hereafter: the celebrated Mr. Boyle is supposed to have been one of the first persons who got a glimpse of the electrical light, or who seems to have noticed it, by rubbing a diamond in the dark. But he little imagined, at that time, what astonishing effects would afterwards be produ

ced by the same power. Sir Isaac Newton was the first who observed that excited glass attracted light bodies on the side opposite to that on which it was rubbed.

Charles. How did he make the discovery?

Tutor. Having laid upon the table a round piece of glass, about two inches broad, in a brass ring, by which it was raised from table about the eighth of an inch, and then rubbing the glass, some little bits of paper which were under it were attracted by it, and moved very nimbly to and from

the glass.

Charles. I remember standing by a glazier when he was cementing, that is, rubbing over some window-lights with oil, and cleaning it off with a stiff brush and whiting, and the little pieces of whiting, under the glass, kept continually leaping up and down, as the brush moved over the glass. · Tutor. That was, undoubtedly, an electrical appearance, but I do not remember having ever seen it noticed by any writer on electricity. A complete history of this

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