Signedunsigned
FunctionSlide wire resistances, a form of potentiometer, are designed to produce a given electrical resistance depending on the points at which the electric contacts touch the wire.
In this particular one the resistance is varied by turning the crank. The scales on the track of the slides and on the crank give the number of turns and fractions of turns of wire that are currently part of the circuit.
It was probably shop-made at Harvard.
ProvenanceFrom the Jefferson Physical Laboratory. Possible made there.