Roller escapement switch, 1885
This is a quick break automatic switch (an early form of circuit breaker). It is held in position by a straight electro-magnet. When the attraction of the magnet reduces, the catch is released and the circuit is broken. This is important because direct current electricity needs to be switched on and off with a quick action to avoid drawing an arc across the contacts.
It was made by the Electric Power Storage Company, who were probably the first electric battery company in the world. The company specialised in the manufacture of storage accumulators for power stations supplying direct current to consumers. The accumulators provided a supply for the small overnight demand, allowing the steam-powered generators to be shut down. This switch was probably designed to be part of the company’s accumulator charging equipment for power stations.