Battery Wall Set
Pattern No. B320
LOUD SPEAKING WALL SET
Comprises Loud Speaking Receiver, Pattern No. B75, and Induction Coil, the Receiver being mounted on, and the Coil enclosed in, a Walnut block as illustrated below ; also a Hand Transmitter, Pattern No. B10.
With this installation no bell is required, as in order to call attention the Transmitter is held to the mouth whilst the Battery Key is kept depressed, the person required being then called by name.
The primary object for which the Set has been devised, is for communicating between a private room, and an outer office. By its use the principal can send any message to his clerks without leaving his chair, and unless the key in the Hand Transmitter is pressed no conversation taking place in the private room can be heard in the outer office. With this Set conversation can only take place one a way.