Inventions in the Century

by William Henry Doolittle

2. The galvanic or voltaic battery by Volta in 1800.

3. The galvanic influence on a magnetic needle by Romagnosi (1802) Oersted (1820).

4. The galvanometer of Schweigger, 1820—the parent of the needle system.

5. The electro-magnet by Arago and Sturgeon—1820-1825—the parent of the magnet system.

Then followed in the third decade the important series of steps in the evolution, consisting of:—

First, and most vital, Henry’s discovery in 1829 and 1830 of the “intensity” or spool-wound magnet, and its intimate relation to the “intensity” battery, and the subordinate use of an armature as the signalling device.

Second, Gauss’s improvement in 1833 (or probably Schilling’s considerably earlier) of reducing the electric conductors to a single circuit by the ingenious use of a dual sign so combined as to produce a true alphabet.

Third, Weber’s discovery in 1833 that the conducting wires of an electric telegraph could be efficiently carried through the air without any insulation except at their points of support.

Fourth, Daniell’s invention of a “constant” galvanic battery in 1836.

Fifth, Steinheil’s remarkable discovery in 1837 that the earth may form the returning half of a closed galvanic circuit, so that a single conducting wire is sufficient for all telegraphic purposes.