Figure 12. — Use of the Duboscq arc light to 

 produce a rainbow for a scene in the opera 

 "Moses" at the Paris Opera House in i860. 

 From La Lumiere electriquc, July 15, 1880, vol. 

 2, p. 287. 



Versailles. '^ Nevertheless, neither the military nor 

 peacetime applications of the arc light took root in 

 contemporary technology. The problems of how to 

 make carbons for the arcs and of how to maintain 

 the carbons at the proper distance and in the same 

 place were more or less solved by 1860, but such 

 endeavors were premature and could have no lasting 

 results until an adequate source of electrical power 

 could be found. 



Chemical cells had ijeen used as a source of power for 

 the arc lamp but they were admittedly quite expensive. 

 A number of studies had been made showing just how 

 much greater was the cost of producing light by 

 Bunsen cells than by gas or oil, and E. Becquerel 

 concluded that, in Paris, the cost of such light was^at 

 least six times that of gas.-" Another factor that had 

 to be considered was that the acids used constantly 

 gave off noxious fumes and \vere dangerous for 



Figure 13. — A later version 

 Duboscq arc-light regulator. 

 January 28, 1864, vol. 24, p. 



(1864) of the 

 From Cosmos, 



" "Eclairage," La Grande Etwyclopedie, Paris, n.d., vol. 15, 

 pp. 341—346; Hippolyte Fontaine, Eclairage a Velectricite, Paris, 

 1879, ed. 2, p. 242 (this may refer to the use of electrically 

 detonated mines in the defense of Venice rather than to the 

 electric light; see Journal of the Telegraph, New York, 1868, 

 vol. 1, no. 25, p. 3); Joseph Henry to Alexander Bache, 

 August 21, 1863, in archives of the Smithsonian Institution; 

 Boston Daily Advertiser, August 8, 1863; American Journal of 

 Science, 1863, ser. 2, vol. 36, pp. 307-308. 



'-" Becquerel, op. cit. (footnote 13); Cosmos, 1857, vol 9, pp. 

 41 7-420. 



PAPER 30: DEVELOPMENT OF ELECTRICAL TECHNOLOGY IN THE 19TH CENTURY: III 



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