Mining and Engine House Telephones
POCKET TYPE OF MINING TAPPING TELEPHONE.
(For use in connection with Patterns Nos. B365, B370 and B375)
Pattern No. B380
This instrument is fitted with Ringing, and Speaking Keys. The line wires are run bare, and the expanding arms of the telephone are intended to hook one to each line, so establishing immediate connection. The Receiver is used both as Receiver and Transmitter, and although not so efficient as a Special Transmitter it still gives good results, and possesses the advantage of portability.