tangent galvanometer
Date: circa 1870
Inventory Number: 2006-1-0015
Classification: Tangent Galvanometer
Subject:
Maker: Adolphe Gaiffe (1832 - 1887)
Maker: Buff & Berger (1871 - 1898)
User: Lehigh University (1865-present)
Cultural Region:
City of Use:
Dimensions:
galvanometer: 52.1 × 43.2 × 35.6 cm (20 1/2 × 17 × 14 in.)
dial: 2.9 × 27.6 × 27.6 cm (1 1/8 × 10 7/8 × 10 7/8 in.)
Description:
Helmholtz-style galvanometer with two identical current-carrying coils. Compass with double-pointed needle contained in removable circular glass-topped brass case with etched silver scale. Compass mounted on cylindrical brass support on circular steel tripod base with three leveling screws. Base has two small tubular spirit (bubble) levels and three brass binding posts.
Signedon instrument: A. Gaiffe / 40 rue St. André des arts / à Paris
on brass graduated circle: Buff & Berger
on brass graduated circle: Buff & Berger
Inscribedpainted in white on base: R318.
FunctionThis galvanometer was used by Isaac Adams and Barry MacNutt at Lehigh University in conjunction with a reversing switch in a series of experiments designed to try to measure the horizontal component of earth's magnetic field.
A tangent galvanometer measures the strength of an electric current. It has a circular coil with a turn of wire and a magnetic needle at the center that is either balanced on a point or suspended by a fiber of silk or quartz. The meter has to be first aligned in the north-south direction and thus the instrument takes into account the earth's magnetic field. When a current is sent through the coil, the needle is deflected according to the vector sum of the field produced by the earth and by the unknown current in the coil. The tangent of the needle's angle of deflection is proportional to the strength of the unknown current producing it.
For more information, go to the following website.
A tangent galvanometer measures the strength of an electric current. It has a circular coil with a turn of wire and a magnetic needle at the center that is either balanced on a point or suspended by a fiber of silk or quartz. The meter has to be first aligned in the north-south direction and thus the instrument takes into account the earth's magnetic field. When a current is sent through the coil, the needle is deflected according to the vector sum of the field produced by the earth and by the unknown current in the coil. The tangent of the needle's angle of deflection is proportional to the strength of the unknown current producing it.
For more information, go to the following website.
Historical AttributesDr Adams had Gaiffe make the galvanometer (his wife was related to Gaiffe). Used throughout Dr Adams career. Documentation (including photographs) relating to the experiment can be found in the instrument's file.
Curatorial RemarksBuff & Berger may have been called to replace the brass case with the graduated circle. This company was famous for its surveying instruments.
ProvenanceUsed by Professors Isaac Adams and Barry MacNutt at Lehigh University.