Signedon plaque base: CAMBRIDGE / INSTR. CO., INC. / OSSINING, N.Y. / No. ________ ; CAMBRIDGE / INSTRUMENT CO., L.T.D. / ENGLAND / CAMPBELL VIBRATION / GALVANOMETER / No L-36255
Inscribedmarked on edge of base: 225
FunctionThis Campbell's vibration type galvanometer has a mirror supported by a pair of upper and lower strings. A small pulley sheave adjusts the vibrating length of the string and the sheave's position can be moved upwards and downwards with a horizontally-mounted lever that tunes the galvanometer to a resonance frequency that is equivalent to the optimal length of the string. A brass adjustment knob for string tension is mounted next to the lever, and there is a spring to load the tension of the vibrational strings next to the suspension tube. When current is introduced into the string (wire) in the presence of a magnetic field, the string moves.
ProvenanceFrom the Department of Physics, Harvard University, 1/8/1957.