In this machine, represented here, a is the glass cylinder, and b b are the wheels by which it is made to turn round. These wheels are worked by the handle which you see on the lower one. The rubber is pressed against the glass cylinder on the side of it that you do not see. You can see the standard that holds the rubber. At c is a piece of oiled silk that is fastened to the rubber, and lies upon the glass cylinder, serving to keep it free from dust. At d you see a receiver, as it is called, which receives the electricity as fast as it is produced. This is made of brass, and has a glass standard, e. Now, as the machine is worked, the electricity excited by the rubber and the glass passes off continually to this receiver, and there it stays collected on the surface of it, for it can not go down the standard. Why is this? you will ask. It is because glass, though a very good thing to make electricity with, is very slow to let the electricity pass over it. I shall tell you more about this soon.
Electricity in the receiver.
Well, here is the electricity all over this receiver. It stays there because it can not get away. It is ready to go whenever it can get a chance. You would find this out if you should put your finger near that knob that you see on the end of the receiver. Almost all of the electricity in the receiver would pass through your finger into your body, and give you a shock; and if there was much electricity in the receiver, the shock would be harder than you would wish to bear.
How a person can be a receiver.
Now a person can act as a receiver and be charged with electricity just as this brass receiver is. It can be done in this way. The person stands on a stool, such as you see here. The top of this, a, is wood, and the legs, c, c, are glass. These glass legs answer for him as the glass standard does for the receiver of the machine. They prevent the electricity that he gets from passing off. If he stood on the floor, it would pass to the floor as fast as it came to him. As he stands on this stool, he holds in his hand a chain that is fastened to the knob on the end of the brass receiver. You can see now what will happen when the machine is worked. The electricity that goes from the glass cylinder to the receiver does not all stay there, but most of it goes on through the chain to the person on the stool. It can not get from him to the floor, for the glass legs prevent this. Therefore, after working the machine some time, he becomes filled with electricity, just as the brass receiver does on its glass standard, and you can receive a shock from him, for he is now a receiver. If you put your finger to his nose, or chin, or any other part, the electricity will pass to you with a spark, and will give you a shock.
How electricity affects the hair.
A curious effect is produced on the hair when one is thus charged with electricity. The hair stands out straight. This effect is seen in a very amusing way by having a figure of a head with hair on it fastened to the receiver. The hair will stand out as you see here.