1800-1819
Early electric experiments were performed with DC. In 1800, Alessandro Volta published a description of a silver/zinc battery, acknowledging that he did not know how it worked. In 1807, Humphry Davy constructed a practical battery (the picture will be immediately familiar to anyone who works with UPS systems), and demonstrated both incandescent and arc light.
1820
Hans Christian Örsted (1777-1851) discovers that an electric current can cause a compass needle to change directions.
1831
Michael Faraday (1791-1867) builds the first electric generator, the "Faraday disk", proving that rotary mechanical power can be converted into electric power. The race for a practical generator begins.
1832-1860
Various generator schemes are tried, mostly employing permanent magnets to create the necessary magnetic field. Ampère and Pixii make the first hand-cranked version (1832); C.G. Page proposed a reciprocating analogue of the steam engine (1850); and H. Wilde made the commercially successful Alliance generator (1866) for powering arc lamps in lighthouses. (An interesting side note: much of the clever work to improve generators was done by instrument makers, such as E.M. Clarke of London, who used galvanic current to "cure" illnesses.) All of these generators employed permanent magnets.
1866
Werner Siemens (1816-1892) perfects the dynamo, a generator in which part of the generator's working current is used to power the field windings, eliminating both the need for permanent magnets and one of the basic limits to generating electric power. Several other inventors, including Wheatstone and Wilde, reached almost the same design at almost the same time, but there is no doubt that Siemens had priority.
1880-1890
Arc lamps were common by 1880, but were difficult to maintain. Thomas Edison (1847-1931) found a simpler solution: in 1879, he perfected a practical incandescent light. More importantly, he subsequently developed and marketed all the bits and pieces for a complete distribution system: underground cables, electric meters, wiring, fuses, switches, and sockets. Although Edison initially was a proponent of DC, when Westinghouse and Tesla promoted more efficient AC, he eventually switched. By 1882, Edison had installed three 125-horsepower "Jumbo" generators at the Pearl Street Station in New York, which fed power to 5,000 lamps in 225 houses. By 1895, electricity was widely available in commercial sections of large cities. |
