Page:Incandescent electric lighting- A practical description of the Edison system.djvu/43

 from the screw shell by the plaster of Paris, a non-conductor of electricity.

This is the coarse the electric current would take when the lamp is in operation.

In the socket is also arranged a screw shell, to receive that on the base of the lamp; while the button on the bottom of the lamp base, comes into intimate contact with a similar button in the lamp socket.

The socket has upon its bottom a threaded piece by which it may be arranged upon a gas fixture chandelier, or regular electric light fixture; and when thus arranged, has leading into it, two wires,—one permanently attached to a metal piece connected directly with the screw shell of the socket, while the other is attached to a metal piece which can be brought into circuit with the button in the socket, by means of a metallic connection carried on the shaft of a key arranged to rotate in the socket.

By rotating this key, shown projecting from the socket, the connection between