The Latest and Most Approved Instrument for communication on deck is the Pillar Telephone, represented by the above illustrations.
This Loud-speaking Instrument, which is generally fitted on the Forecastle, on the navigating Bridge, and on the Docking Bridge Aft, is of
Water tight Construction, and is mounted on a massive Polished Brass or Gun-metal Pillar.
A Special Switching Device, combining a Switch and Indicator with automatic replacement, can be fitted to the Apparatus. and is, generally supplied to the Bridge Apparatus communicating with the Forecastle, Crows’ Nest, Engine Room, and Poop.
Taken from the GEC Telephone Catalogue, K Section, 10th Edition, 1908