Foucault current demonstration device
Date: 1855-1890
Inventory Number: DW0329
Classification: Electromagnetic Apparatus
Dimensions:42 × 38 × 24 cm (16 9/16 × 14 15/16 × 9 7/16 in.)
Accessories: box of feet for base
4 feet consisting of brass strips with screw holes at either end and iron points
8 screws, somewhat rusted
DescriptionGear assembly mounted in trapezoidal iron frame driving a copper wheel mounted between two magnets. Entire assembly is mounted on a wooden base.
The gear assembly consists of a cast-iron crank with a wooden handle driving three coupled brass wheels with six spokes each. Each wheel is slightly smaller than the one below it and is coupled with the wheel above it through a small gear joined to the hub of the upper wheel.
The copper wheel spins between the magnets, which consist of two blocks of iron with semicircles at the ends straddling the wheel. The rear block has two screws in the top. The blocks are mounted on cores, most likely composed of soft iron, around which are wrapped coils of copper wire insulated with a material that may be gutta percha. Each coil is connected by a wire to a binding post on the left side of the base. They are mounted on a block of rusted iron.
Accompanying the instrument are four rusted iron spikes that look like bullets. They are mounted on strips of brass metal with screws in either side.
The wooden base has two levels. The top level is rectangular and smaller than the bottom. The bottom is in several parts glued together, the two sides wider than the middle.