This is a portable, D'Arsonval type moving coil reflecting galvanometer, contained in a painted grey wooden box, with two sets of terminals mounted on the exterior of the box, two for connection of a 6-volt AC or DC power source, and the other two for test connection.
The top of the box hinges back to show a horseshoe magnet lying horizontally. The galvanometer system is a light coil assembly with a pivotable mirror suspended between the poles of the horseshoe magnet.
D'Arsonval type galvanometers operate by means of a light coil of wire being suspended from a metal ribbon a few thousandths of a millimetre wide and less than 0.02mm thick. The light system comprises a lamp, lamp-holder and lens assembly. Mirror and light assembly operate in the same plane, to reflect the light beam on to a frosted glass panel on the front inside of the box. The glass panel is marked with a scale graduated in millimetres. The coil, which can freely rotate between the permanent magnet poles carries the small mirror which acts as the optical pointer, showing the coil position. Current is conducted to and from the coil by the suspension ribbons.
A galvanometer is an instrument for detecting and measuring electric current. It is an electromechanical transducer that produces a rotary deflection through a limited arc in response to electric current flowing through its coil.
Information on badge attached to lid 'LEEDS & NORTHRUP CO. / PHILADELPHIA PENNSYLVANIA / MADE IN U.S.A.'. Beneath this, 'CAT. NO. 2420 A', the Leeds and Northrup logo and 'SERIAL NO. 1114281'.