rotating slide wire
Date: 1893-1912
Inventory Number: 0416
Classification: Resistance
Subject:
Maker: Hartmann & Braun AG (1879 - 1999)
Supplier: Queen & Company (1893 - 1912)
User: Department of Physics, Harvard University (founded 1884)
Cultural Region:
Place of Origin:
City of Use:
Dimensions:
18.4 × 24.2 × 17.6 cm (7 1/4 × 9 1/2 × 6 15/16 in.)
Description:
A 4-inch rotating marble drum on fixed bearings, 10 turns of fine wire in contact with a sheave on wheel on a sliding rod. Mounted on hard rubber panel on box containing resistences of 1, 10, 100, and 1000 ohms, plugs and contacts.
Signedstamped on panel: HARTMANN & BRAUN FRANKFURT A/M NO 69
marked on oval plate: SOLE AGENTS FOR U.S.A. / JAMES W. QUEEN & CO. / PHILADELPHIA
marked on oval plate: SOLE AGENTS FOR U.S.A. / JAMES W. QUEEN & CO. / PHILADELPHIA
Inscribedstamped on panel: RICHTIG BEI 19 GRAD CELSIUS
FunctionSlide wires are a form of very precise variable resistances. Like most resistance boxes, it contains several resistances of increasing magnitudes that can be activated or bypassed, in order to add their values. In addition to these, they include a coil of wire through which the current will pass. The resistance will vary depending on the location of a point of contact with the wire. This allows for a continuous, rather than stepwise increase in the resistance. In this particular case, the resistance is changed by turning the spool handle.
Like other continuous devices for variable resistance, they were mostly used for the precise measurement and regulation of electric currents.
Like other continuous devices for variable resistance, they were mostly used for the precise measurement and regulation of electric currents.
Curatorial RemarksPart of Kirchoff Bridge.
ProvenancePhysics Department, Harvard University. (Lyman 238 April 6 1963).