Pattern No. B30
Comprises Granular Carbon Transmitter, Breastplate, Battery Switch, Elastic Web,
Receiver Cord, 5-way Plug, Cord, and 5-way Jack.
This apparatus is made use of in conjunction with a Headgear Receiver, Pattern No. B65. (See also Patterns Nos. B60 and B70.)
This Breastplate Transmitter is largely employed for Switchboard work, and is also particularly useful where letters are dictated through the telephone, as, used by a clerk in conjunction with a Headgear Receiver, it enables the principal while still sitting in his private room to dictate to the former (whose hands are free for writing shorthand notes, typewriting, etc.) the fact of the clerk being in a distant office making no difference. The Transmitter is so arranged that when the mouthpiece is turned downwards the speaking battery is disconnected, thereby obviating wastage of battery energy.
The most convenient description of Desk Set to be used for dictating purposes in connection with a Headgear Receiver and Breastplate Transmitter is Pattern No. B345.