This is a 50cm sliding-wire Wheatstone bridge produced by Philip Harris of Birmingham. This example features a 50cm slide wire ruler across the centre, and surmounted by eleven brass terminal nut knobs. The ruler is engraved with Philip Harris & Co (1913) and the wood is in perfect condition. The copper plating has some scratching to it.
A Wheatstone bridge is designed to measure resistance in a conductor by comparing a wire with known resistance to one with unknown resistance. It is used to study the variation of resistance of a conductor with length, diameter and material.
