The induction coil provids very high voltages (several tens of thousands of volts) from a DC source. The principle is based on a step-up transformer comprised of a primary winding, a few tens of turns, and a secondary winding, hundreds of thousands of turns. To produce permanent sparks, it is necessary to cut the current flowing in the primary winding with a shaker (electromagnetic bell).
The induction coil stands 6" tall, 11.5" wide and 7" long. Each spark rod measures 5.25" long and 2.25" wide