Text above from lecture notes of Henry Clay Cameron (1846) ….. “If we wrap a bundle of soft iron wires with a short thick wire, and wrap a long thin wire over this, and connect one end of the thick wire with a small battery, and make and break the connection of the other upon a file, a person who catches hold of the ends of the fine wire will receive a violent shock. We can regulate the shock by the size of the bundle of wire. We may thus combine electrical and magnetic inductions in the little machines. The shocks take place only at the moment of making and breaking contact.”