Dated 1850-1870. From Scientific apparatus, musical instruments and telegraph equipment, [1834-1875].
Telegraph relay used for long distance lines by re-transmitting a signal to the receiver or other apparatus. Consists of a circular brass mechanism with a glass top, and brass knobs (labelled D, D, T, M, U, U) mounted on a circular wooden base. [See K/PP107/1/4/100 for a description of improvements for relay for automatic telegraph.]