In 1858 Thomson patented his telegraph receiver, called a mirror galvanometer, for use on the Atlantic cable.
Mirror Galvanometer after Thomson - Szymanski; with astatic magnet system and directing magnet with wire connecting blocks for putting the coils in parallel in 2 groups and in series.
The 4 coils have a resistance of 4 ohms each. By removing the front wall the galvanometer can be opened and therefore easily and quicly adjusted. The case is mahogany.
The instrument is highly sensitive and is very suitable for experiments with thermo-electric currents and for demonstrating the currents on cutting the lines of force.