Jablochkoff, Paul

SUBJECT AREA: Electricity, Public utilities

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b. 14 September 1847 Serdobsk, Russia

d. April 1894 St Petersburg, Russia

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Russian military engineer and inventor of an electric "candle", the invention of which gave an immense impetus to electric lighting in the 1870s.

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Jablochkoff studied at the Military Engineering College in St Petersburg. Having a scientific bent, he was sent to the Military Galvano Technical School. At the end of his military service in 1871 he was appointed Director General of the Moscow-Kursk telegraph lines for the Midi Railway Company. At this time he began to develop an interest in electric lighting, and in 1875 he left the Imperial Telegraph Service to devote his time exclusively to scientific pursuits. He found employment at the workshop of M Bréguet in Paris, where Gramme dynamos and Serrin arc lamps were being constructed. After some experimentation he found a means of producing a carbon arc that regulated itself without any mechanism. This lamp, the Jablochkoff candle, with two carbon rods placed parallel to each other and so close that an arc formed at the ends, could continue to burn until the rods were consumed. Plaster of Paris was used to separate the two electrodes and crumbled away as the carbon burned, thus exposing fresh carbon. These lamps were used in May 1878 in Paris to illuminate the avenue de l'Opéra, and later in Rome and London, and in essence were the first practical electric street lighting. Since there was no regulating mechanism, several candles could be placed in a single circuit. Despite inherent defects, such as the inability to restart the lamps after they were extinguished by wind or interruption of supply, they remained in use for some purposes for several years on account of their simplicity and cheapness. In 1877 Jablochkoff obtained the earliest patent to employ transformers to distribute current in an alternating-current circuit.

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Bibliography

11 September 1876, British patent no. 3,552 (Jablochkoff's candle).

22 May 1877, British patent no. 1,996 (transformer or induction coil distribution).

Further Reading

W.J.King, 1962, The Development of Electrical Technology in the 19th Century, Washington, DC: Smithsonian Institution, Paper 30, pp. 393–407 (a detailed account). W.E.Langdon, 1877, "On a new form of electric light", Journal of the Society of

Telegraph Engineers 6:303–19 (an early report on Jablochkoffs system).

Engineering (1878) 26:125–7.

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