Silvanus P Thompson's 'valve' telephone, 1882-85.

 
Silvanus P Thompson's 'valve' telephone, 1882-85.
4 0 c m
 
30cm
actual image size: 22cm x 32cm

Description

The New Telephone Company, formed in 1885, offered these telephones for sale at £16 a pair, in competition with the United Telephone Company which, with acces to Edison and Bell patents, offered a year's rental for £16. The human voice was used to open or close a valve which regulated the electric current. The microphone, a carbon ball resting on three carbon points at the end of a speaking tube, resembled a mechanical ball valve. The receiver used a parchment diaphragm, which Bell had rejected. It was found to infringe the Edison and Bell patents and the New Telephone Company was forced into liquidation in 1889.

Image Details

Image Ref.
 
10212456

© Science Museum / Science & Society Picture Library

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