Mining and Engine House Telephones
Pattern No. B365 & B370
This pattern is of entirely new design, and is constructed to withstand very rough handling.
The Transmitter, Induction Coil, and Switch Springs are mounted on a substantial black fibre slab, the whole being enclosed in a water-tight and gas-tight cast iron case.
The mouthpiece is of gun-metal, and the receiver is fitted in an exceedingly strong gun-metal outer case.
Pattern No. B365 - with extra receiver
Pattern No. B370 - without extra receiver