Nicholas Joseph CallanBorn 22 Dec 1799; died 10 Jan 1864 at age 64.Irish physicist who pioneered in electrical science. Heinvented the induction coil (1836) before that of better-known Heinrich Ruhmkorff. Callan's coil was built using a horseshoe shaped iron bar wound with a secondary coil of thin insulated wire under a separate winding of thick insulated wire as the “primary”coil. Each time a battery's current through the “primary”coil was interrupted, a high voltage current was produced in the electrically separate “secondary”coil. By 1837, Callan used a clock mechanism to rock a wire in and out of a small cup of mercury to interrupt the circuit 20 times/sec on a giant induction machine, producing 15-inch sparks (estimated at 600,000 volts).« |
