NATIONAL TELEPHONE COMPANY
Pattern No. B27
Comprises - Granular Carbon Transmitter, Double Pole Receiver, Cord, Automatic Switch-Hook, Induction Coil, Lightning Arrester, Magneto Generator, Bell, Special Key, Battery Box and Writing Desk with Paper Clip.
This is a larger make of the same form of instrument B26 and the generator also provides extra ringing power; further, there is ample space for large batteries.
The Key placed in the centre of the apparatus. behind the paper clip, may be depressed to improve the hearing (especially on long lines) when receiving a message, but must not be when speaking. It cuts out the bell while ringing and the secondary of of the induction coil when receiving a message. This arrangement prevents sounds near the instrument from being overheard at the other end and reduces the resistance.
The set is a very efficient one suitable for exceptional circumstances.
Taken from the 1903 Catalogue.
Last revised: July 07, 2020