NATIONAL TELEPHONE COMPANY
Mining and Engine House Telephones
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.
Last revised: July 07, 2020