Beautiful model of an early electric motor fairly similar to the one invented by Giuseppe Domenico Botto and described by him in Notizia sopra l'applicazione dell'elettromagnetismo alla meccanica (Turin, c. 1834). The base has a drawer with 14 glass compartments for the electro-chemical battery (whose elements are missing). The rocking motion of a mobile coil between two fixed coils is transmitted to a large brass wheel on a wooden frame by a small pulley and crank. The to-and-fro motion is maintained by a commutator consisting of two rocking brass arms dipping into mercury contact cups. This arrangement alternates the direction of the current in the fixed coils. The earliest electromagnetic engines and motors converted electrical energy into mechanical energy by imitating the rocking motion of the steam engine, the pressure of the steam being replaced by the attraction of an electromagnet or armature. Provenance: Lorraine collections.