Campbell vibration galvanometer
Date: 1900-1919
Inventory Number: 0262a,b,c,d
Classification: Galvanometer
Subject:
Maker: Robert W. Paul Instrument Company (1891 - 1919)
Supplier: James G. Biddle Company (fl. 1890 - 1950)
User: Harvard Engineering School (1918 - 1951)
Cultural Region:
Place of Origin:
City of Use:
Dimensions:
28.6 × 27.8 × 27.8 cm (11 1/4 × 10 15/16 × 10 15/16 in.)
Description:
Campbell's type galvanometer with bifilar suspension above and below small coil, mirror and spring in fixed circular magnet. Cylindrical brass cover (b) with circular viewing window. Brass suspension tube with horizontally-mounted brass knob for adjusting vibrational wires. Round, black brass base (a) with three brass leveling screws and two binding posts. Similar to instrument 0225 in this collection.
Signedon top of case: Rob. W. Paul / London. N. / CAMPBELL VIBRATION GALVANOMETER / No. 36
on plaque on front of case: IMPORTED BY / JAMES G. BIDDLE / PHILADELPHIA, U.S.A.
on plaque on front of case: IMPORTED BY / JAMES G. BIDDLE / PHILADELPHIA, U.S.A.
Inscribedon case: H.U. 104-A
FunctionThis Campbell's vibration type galvanometer was used in the Engineering School at Harvard. The instrument is equipped with 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.
Primary SourcesPaul Instrument Catalog - pg. 691-693
ProvenanceFrom the Harvard Engineering School, 12/19/1956.