Siemens Galvanometer

Round wooden base 8” in diameter; made in three pieces and set on three leveling screws; apparatus pivoted and revolving on base; slate disc, 6 1/2” in diameter and graduated, 0 to 140, on each side “A & B”, with German silver bridge wire set in the edge; movable arm carrying sliding contact with bridge wire; suspended astatic needle enclosed in round glass case 3” in diameter; 5 binding post connections, marked “I II III IV V”, and three resistance coils marked, “10, 100, 1000.” Marked, “Siemens Brothers, London, No. 780.” Suspension fibre missing. This form of galvanometer was introduced into this country about 1870 and for ten or fifteen years was extensively used in testing telegraph lines, etc., et.,. Exhibition label: "This instrument was used extensively as a sine galvanometer and as a Wheatstone bridge in testing early telegraph lines."

Currently not on view