tangent galvanometer?
Date1870-1890
Inventory NumberDW0071
ClassificationGalvanometer
Subject
Maker
Eugène Deschiens
1866 - 1894
Cultural Region
Place of Origin
Dimensions17 × 12 × 12 cm (6 11/16 × 4 3/4 × 4 3/4 in.)
Material
DescriptionA small compass needle with long wire pointer encased in cylindrical brass case with glass top. The compass and case are surrounded by a coil of wire in a brass ring on a short post and a round brass base. The silvered dial under the glass scale is a graduated half circle from 0 to 90 degrees in both directions, divided in single units.
Signedunder glass case: E. Deschiens / Paris
FunctionA tangent galvanometer is a device used to measure the strength of an electric current. It uses a compass needle to compare a magnetic field generated by the unknown current to earth's magnetic field. The instrument is first rotated until the earth's magnetic field is parallel with the plane of the coil, then an unknown current is sent through the coil, generating a magnetic field that causes a deflection in the compass needle that can be measured on a scale. The tangent of the angle of deflection is proportional to the strength of the current.
A thorough explanation about the basics of this instrument is found here.
A thorough explanation about the basics of this instrument is found here.
ProvenanceDavid Wheatland purchased from Roux-Devillas Paris, March 29, 1966 (lot 4/51).
Department of Physics, Harvard University
Date: circa 1893
Accessories: extra scale (0190b)
Object number: 0190a
