Telegraph works bridge with galvanometer. London Telegraph Works Silvertown early 20th c Brass, glass, a.o. Contained in a purple velvet lined mahogany cabinet, 20,5 x 19,5 x 14,5 cm, with hinge lid and brass lock (key missing). Unusual example of a Wheatstone bridge with a gutta-percha (?) bed marked "N° 518 Telegraph works Silvertown London Patent", bridge terminals and contact points. The Silvertown Telegraph Works, a subsidiary of the India Rubber, Gutta Percha and Telegraph Works Company, was founded by Stephen William Silver in March 1864 and continued making telegraph equipment until 1930.