Images(2)

mirror galvanometer, type-P

Date1905-1910

Inventory NumberWJ0184

ClassificationGalvanometer

Subject

Maker Leeds & Northrup Company 1903 - 1995

Cultural Region

Place of Origin

Dimensions6 x 22.9 x 15.9 cm (2 3/8 x 9 x 6 1/4 in.)

Material

DescriptionThis is a type-P wall galvanometer, fixed by two mounting brackets at the top of the rectangular wooden base. Two electrical connectors are also found on the base. The central chamber is made of metal covered in black paint. Inside is a small circular mirror attached to a rectangular coil. The coil is set around a block of metal. The mirror and coil are suspended by a thin wire (missing) at the top and a spring at the bottom. The wire tension is adjusted by the rod above the instrument. The covering plate has a central window which allows a light beam to be reflected on the galvanometer mirror. The sensitivity of the instrument has been recorded on a plastic sheet lying at the bottom of the chamber.

Signedon cover: LEEDS & NORTHRUP CO. / PHILADELPHIA

Inscribedinside chamber: SENS. 0.002 uc/mm / C.D.R.X. 11,000 [ohm] / PERIOD 24.5 sec / RESIST. 2220 [ohm] on base, stenciled: HARVARD / PSYCHOLOGICAL / LABORATORY

Curatorial RemarksThese devices were manufactured by Elmer G. Willyoung & Co. of Philadelphia until 1893, when Willyoung sold his business to Morris E. Leeds. Starting in 1903 Leeds joined forces with Edwin Northup to form Leeds & Northrup.

FunctionElectrical apparatus used in measuring very low voltage potentials for calibrating equipment. When a current is applied to the galvanometer, a small variation will create a torque motion on the mirror. A light is then beamed on the mirror, which will be redirected away from the galvanometer towards a graduated scale. The position of the reflected light on that scale will indicate the variation of the current detected by the galvanometer.

ProvenancePsychology Department, William James Hall, Harvard University.