Switch, Automatic

A switch opened and closed by the electric current. It is used for lighting distant incandescent lamps. It includes one or two electro-magnets operated by two push buttons. In the usual arrangement one button is black and the other white, for extinguishing and lighting respectively. When the white button is pushed it causes a current to pa through one of the electro-magnets. This attracts its armature, thereby making a contact and throwing the lamps into the lighting circuit. Then they remain lighted until the black button is pre ed. This excites the other magnet, which attracts its armature, breaks the contact and extinguishes the lights. The object of the automatic switch is to enable distant lamps to be lighted without the nece ity of carrying the electric leads or wires to the place whence the lighting is to be done. A very small wire will carry enough current to operate the magnets, and open circuit batteries, such as Leclanché batteries, may be used as the source of current for the switch, but generally the lighting current is used for the purpose. A single magnet may do the work. When the lighting button is pre ed the magnet is excited, attracts its armature and holds it attracted, until by pre ing the black button the current is turned off from it. In this case the lighting current is used to excite the magnet.