[Ital., from Galvani, the discoverer in 1791.] It consists of a number of zinc and copper plates connected together, their purpose being the production of a current of electricity. These are arranged in cells, the copper-plate of one being joined to the zinc-plate of the next, and the final copper connected by a wire to the zinc of the first cell. The cells contain a dilute acid, which acts chemically on the metals, and generates an electric current which flows around the circuit of cells and wires. ■ The connecting wire may be many miles in length, as in a telegraph line. The zinc of the first cell is called the negative electrode and the copper of the last cell the positive electrode, the current being supposed to flow from positive to negative. There are many varieties of galvanic batteries in use, and other metals than copper and zinc are employed. Formerly all electric currents were produced by the battery; now it is used only for weak currents, powerful currents being produced by the dynamo (q.v.) (See Electricity.)