Peltier's Cross

A bar of bismuth and a bar of antimony soldered centre to centre at right angles, being notched or halved there to receive or to set into each other. It is used to demonstrate the Peltier effect, q. v. To one pair of ends are connected the terminals of a battery circuit; to the other pair are connected the terminals of a galvanometer. The galvanometer by its deflections in one and then in the other direction indicates that the junction is heated when the current pa es from antimony to bismuth and vice vers a. It thus illustrates the heating and cooling of a thermo-electric junction by a current of electricity. The current from the battery by the Peltier effect either heats or cools the junction, as the case may be. This heating or cooling them produces a thermo-electric current in the galvanometer circuit. The battery has no direct influence on the galvanometer.