Scientific, Instrument, Physics, Electricity, Galvanometer, Antique, Boston, 1906

L.E. Knott Apparatus Co.
Reflecting Galvanometer with Moving Coil (D’Arsonval)
Boston, Massachusetts: c. 1906
Mixed metals, brass, and glass, on a wooden base
8 inches high, 6.5 inches wide, 5.75 inch diameter base
$900

A reflecting galvanometer (also called a mirror galvanometer), an electrical testing instrument used to determine the presence, direction and strength of an electric current in a conductor. This model is of typical form, with a moving coil of many turns of fine wire encased within a permanent magnet, contained within a rectangular case with two opposing mirrors, on a circular turned wood base with three leveling screws and two binding posts. The first galvanometers had a magnetic needle that moved in response to the flow of current in a nearby conductor. Reflecting galvanometers such as this one improved the accuracy of these devices by using a moving beam of light that reflects off the mirrors and onto an external scale. The Harvard University Collection of Historical Scientific Instruments has the same model in its collection, which they say was used in the 1910s for classroom demonstrations in physics and electrical engineering laboratories to measure very small electrical currents and voltage differences.

Product description continues below.