Hjorth, Soren

SUBJECT AREA: Electricity

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b. 13 October 1801 Vesterbygaard, Denmark

d. 28 August 1870 Copenhagen, Denmark

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Danish engineer and inventor who first proposed the principle of the self-excited dynamo.

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After passing a legal examination, Hjorth found employment in the state treasury in Copenhagen and in 1830 advanced to be Clerk of the Exchequer and Secretary. In 1834 he visited England to study the use of steam road and rail vehicles. Hjorth was involved in the formation of the first railway company in Denmark and became Technical Director of Denmark's first railway, a line between Copenhagen and Roskilde that opened in 1847. In 1848 he petitioned the Government for funds to visit England and have built there an electric motor of his own design with oscillating motion. This petition, supported by Hans Christian Oersted (1777–1851), was granted. A British patent was obtained for the machine, an example being exhibited at the 1851 Great Exhibition in London. Turning his attention to the generation of electricity, he conceived as early as May 1851 the dynamo electric principle with self-excitation that was incorporated in his patent in 1855. Unfortunately, Hjorth held the firm but mistaken belief that if he could use his dynamo to drive a motor he would obtain more power than was consumed in driving the dynamo. The theory of conservation of energy was being only slowly accepted at that time, and Hjorth, with little scientific training, was to be disappointed at the failure of his schemes. He worked with great perseverance and industry to the end of his life on the design of his electrical machines.

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Bibliography

11 April 1855, British patent no. 806 (Hjorth's self-excited dynamo).

11 April 1855, British patent nos. 807 and 808 (reciprocating and rotary electric motors).

Further Reading

S.Smith, 1912, Soren Hjorth, Copenhagen (the most detailed biography).

1907, "Soren Hjorth, discoverer of the dynamo-electric principle", Electrical Engineering 1: 957–8 (a short biography).

Catalogue of the 1851 Exhibition, 1851, London, pp. 1, 359–60 (for a description of Hjorth's electromagnetic engine with oscillating motion.

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