Leon Foucault initiated progress toward a solution 

 in 1844 with his photometric studies on the radiation 

 from a carbon arc. He discovered that an electrode 

 that was consumed more uniformly and more slowly 

 than charcoal could be made from the hard carbo- 

 naceous deposit formed in coke retorts. He then set 

 to work to devise an automatic regulator for the arc, 

 but, in 1 848, he was surprised to read that W. Edward 

 Staite of London had applied for a patent on a regu- 

 lator that appeared to be based on the same principle 

 as his.^ Upon invitation by Foucault, a committee 

 from the Academic des Sciences examined his 

 laboratory and verified that his work was independent 

 of Staite's. However, Foucault's automatic regulator 

 (fig. 2) for the arc was too delicate and too complicated 

 for use even in the laboratory, and it found little 

 application until it was modified by Duboscq. 



Staite had begun his work by demonstrating an 

 automatic arc light in a hotel at Sunderland, Durham, 

 in 1847. This light (figs. 3, 4) had finally worked so 

 well that it is said to have remained in use for several 

 years. Public exhibitions in 1848 and 1849 led to 

 what one might consider the first commercial success 

 of the electric light. In May 1849 a ballet called 

 "Electra," especially composed for the purpose, intro- 

 duced the arc light to the public at Her Majesty's 

 Theater in London (fig. 5). The ballet was an 

 instant hit, and a command performance was given 

 for Queen Victoria a few weeks later. A similar 

 application appeared about the same time across 

 the Channel, where Foucault's arc lamp was used to 

 simulate the rising sun in Meyerbeer's latest opera, 

 "Le Prophete." " 



Staite constantly improved his apparatus. In 1849 

 the average time for continuous operation was 45 

 minutes; two years later his arc light could run with- 

 out interruption for 5 hours. He even demonstrated 

 it to the Queen and to her court at the palace. Then 

 he obtained a request in 1852 that seemed to promise 

 a profitable commercial venture. The port of Liver- 

 pool asked him to set up a permanent installation 

 of his lamps on a high tower so as to permit work to 



^ V Illustration, 1849, vol, 13, p. 6; Leon Foucault, "Appareil 

 destine a rendre constante la lumiere einanant d'un charbon 

 place entre les deux poles d'une pile," Comptes rendus, 1849, vol. 

 28, pp. 68-69; Theodose du Moncel, Expose des applications de 

 VeUctricite, Paris, 1856-1862, ed. 2 (5 vols.), vol. 3, pp. 217-219. 



* Emile Alglave and J. Boulard, La Lumiere electrique, son 

 histoire, production et son emploi dans Peclairage public ou prive, 

 Paris, 1882, translated by T. O'Connor Sloane as The Electric 

 Light, New York, 1884, pp. 22-23; Mechanics Magazine, 1847, 



Figure 4. — Staite's arc light of 1848. From 

 Illustrated London News, November 18, 1848, 

 vol. 13, p. 317. 



vol. 46, pp. 621-622; 1848, vol. 48, p. 453; vol. 49, p. 382; 

 Illustrated London News, 1848, vol. 13, pp. 317, 343, 368, 378; 

 1849, vol. 14, p. 58; London Times, November 2, 1848; Illus- 

 trated London News, 1849, vol. 14, p. 293; Jules A. Lissajou, in 

 Bulletin de la Societe d' Encouragement pour VIndustrie Nationale, 

 1868, ser. 2, vol. 15, p. 59. Although the Illmtrated London 

 News asserts the device was copied in France, Lissajou claims 

 it was used on April 16, 1849, the opening date for Meyerbeer's 

 opera. 



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