The induction coil is mounted on a wooden board; the primary and secondary coils, which are isolated from each other, are wound around the same reel; a core made of iron wire can slide in a hole in the centre of the coil. The ends of the primary coil are connected to two clamps, as are those of the secondary coil.
Two small electromagnets are mounted on the board, above which there is an armature in a horizontal position with a return spring and a plate switch supported by two brass columns.

When the primary coil is connected to a battery, the current also passes through the switch, the electromagnet is magnetized and attracts the armature, and the circuit is broken. The electromagnet’s core is thus demagnetized and the armature rises, closing the circuit again and allowing the current to flow once more; the process is repeated. The repeated interruptions of the current cause an induced current to be generated in the secondary coil, which can be drawn from the clamps.

The instrument is signed by its maker, Alemanno – Gastaldi, Torino.

Devices of this type are widespread in physics laboratories; they illustrate the phenomenon of electromagnetic induction that was discovered in 1831 by the English physicist Michael Faraday (1791 – 1867), which forms the basis of electromagnetism.

Device on display.