A switch for closing a circuit by means of pressure applied to a button.
The button is provided with a spring, so that when pushed in and
released it springs back. Thus the circuit is closed only as long as the
button is pressed. The electric connection may be made by pressing
together two flat springs, each connected to one of the wires, or by the
stem of the button going between two springs, not in contact, forcing
them a little apart to secure good contact, and thereby bridging over
the space between them.