Extension Bell Call

A system of relay connection, q. v., by which a bell is made to continue ringing after the current has ceased coming over the main line. It is designed to prolong the alarm given by a magneto call bell, q. v., which latter only rings as long as the magneto handle is turned. A vibrating electric bell (see Bell, Electric,) is connected in circuit with a local battery and a switch normally open, but so constructed as to close the circuit when a current is pa ed and continue to do so indefinitely. The distant circuit is connected to this switch. When the magneto is worked it acts upon the switch, closes the local battery circuit and leaves it closed, while the bell goes on ringing until the battery is exhausted or the switch is opened by hand.