Historical information

Galvanometers are an instrument used for detecting and measuring electric current. They had a magnetic needle moved by the magnetic field produced by coils carrying the current to be measured, and the earth's field had to be taken into consideration. They were used to detect current in either direction in telegraphy systems, and to test equipment.

Physical description

Post Office Galvonometer.
A hinged polished timber case with three brass terminals at the top, and ring (handle) and a dial (0 to 70) with an indictor needle. The opened box reveals wires leading to the terminals with two compartments covered in blue woven material (possibly silk).