Images(2)

high resistance plug box

Datecirca 1920

Inventory Number1997-1-0402

ClassificationResistance Box

Subject

Maker Hartmann & Braun AG 1879 - 1999

Cultural Region

Place of Origin

Dimensions18 x 26 x 16 cm (7 1/16 x 10 1/4 x 6 5/16 in.)

Material

DescriptionRectangular wooden resistance box consisting of 8 brass blocks arranged in a rectangle with two short arms extending to one side. There are six removeable plugs placed between the brass blocks, and six binding posts placed along these blocks, with the plugs in the center, and the binding posts at the two ends.

These elements are mounted on a hard rubber panel over a rectangular wooden case.

Signedon top of wooden case: HARTMANN & BRAUN / FRANKFURT A.M. / No.4528

Inscribedstamped into side of hard rubber panel: 1 Ohm = 106,3 cm/mm² Hg. 0°C stamped on top of rubber panel, inside rectangle of blocks: Richtig bei 20°C resistances marked: 1000, 10000, 10000, [infinity] 30000

Curatorial RemarksVery similar to 1997-1-0402. May have a 3-digit #--has a Wheatland tag, but no visible number.

FunctionSuch an instrument is used to control the resistance of electric conductors. For a short general description and other images, go to the following website.

The series of brass blocks are connected to one another with the coils underneath. When the plugs are all in, the resistance is negligible. When one or more plugs are removed, the resistance of that or these plugs are introduced into the electric current passing through the box.