To the line, thus hastening the discharge and the return of the relay tongue to its insulated stop.
The Siemens polarized relay, shown in fig.
20, which is the most modern pattern of relay used by the British Post Office, known as the " Post Office Standard Relay."
The coils of the electromagnets are differentially wound with silk-covered wire, 4 mils (= 004 inch) in diameter, to a total resistance of 400 ohms. This differential winding enables the instrument to be used for " duplex " working, but the connexions of the wires to the terminal screws are such that the relay can be used for ordinary single working.