Rheostat

Astronomy

Accession Number: 2019.ast.171

Description:

This rheostat consists of a hollow long cylindrical coil, mounted horizontally. Suspended above this there is a triangular metal rail along which a metal carriage can be slid. This has a plastic top, with a label on the top, and a rectangular base that drops to be within a centimeter of the coil. Beneath this there is a block of metal that contacts the coil surface. At both ends of the coil, brackets emerge perpendicularly; these have screw connectors that can be used to firmly attach electrical wires. The apparatus stands on four metallic legs with holes in the feet, where the instrument be screwed into a surface.

Alternative Name: Variable Resistor

Primary Materials:

Metal: Iron Alloy, Metal: Copper Alloy?, Plastic

Markings:

“MADE IN U.S.A.
CENTRAL SCIENTIFIC CO.
AMP 2.2
OHM 8.9
CENCO RHEOSTAT
BOSTON TORONTO
NEW YORK LOS ANGELES”

Dimensions (cm):

Length = 36.5, Width = 11.3, Height = 12.6

Function:

A rheostat can be used to adjust the resistance in a circuit smoothly and without interruption. The carriage can be slid along the coil to stop the current’s flow along the coil, thus decreasing on increasing the current. The cover is intended to reduce sudden changes in temperature.

Condition:

Good: The instrument is dirty and dusty, but intact. There is some blue-green corrosion at each end of the coil close to where the electrical connectors are. This extends around the bands which hold the connectors in place. The label on top of the sliding carriage is slightly warped and discoloured around the small nails which hold it in place, but in good condition.

Associated Instruments: 2019.ast.170

Manufacturer: Central Scientific Company (Cenco)

Date of Manufacture: Mid-20th Century; before 1968

Provenance:

This object was likely moved from the David Dunlap Observatory in Richmond Hill in 2008, upon the sale of the observatory. It was stored at the Department of Astronomy and Astrophysics until 2017, when it was moved to a new storage location in McLennan Physical Laboratories.