. Bulletin. Science. &0Ma' / Figure 90.—Two views of Siemens' self-excited alternator of 1882. From J. Dredge, Electric illumination, London, (about 1882), vol. I, figs. 274, 275. At first the Alliance machine was used to supply the power, and this allowed the now rather moribund Societe I'Alliance to continue its existence. However, it was soon found that the Gramme generators were more ;' In addition, with his usual in- genuity, in 1878 Gramme devised alternating current generators for 4, 16, and later 32 "candles" (fig. 86).""' One type d'atelier
. Bulletin. Science. &0Ma' / Figure 90.—Two views of Siemens' self-excited alternator of 1882. From J. Dredge, Electric illumination, London, (about 1882), vol. I, figs. 274, 275. At first the Alliance machine was used to supply the power, and this allowed the now rather moribund Societe I'Alliance to continue its existence. However, it was soon found that the Gramme generators were more ;' In addition, with his usual in- genuity, in 1878 Gramme devised alternating current generators for 4, 16, and later 32 "candles" (fig. 86).""' One type d'atelier dynamo was used to provide the current for the electromagnet field coils of one or more alternators. These last had a rotating field, with 8 radial poles, and a stationary armature. The coils were grouped on the stator so that a number of circuits (normally with four "candles" per circuit) could be taken off a single alternator. Each "candle" provided about 100 Carcel units, and, as the following tabulation shows, each consumed about 1 hp.: Cost Candles Length/width/ height {cm.) Weight (kg.) Hp. (£) (francs) 16 89 X 86 X 78 650 600 16 400 10. 000 6 70 X 40 X 52 280 700 6 200 5,000 4 55 X 40 X 48 190 800 4 100 2,500 i« Les Mondes, 1877, vol. 42, pp. 346-347; vol. 43, p. 779. 11* French patent 120649 (October 23, 1877; additions, December 3, 1877, and September 1, 1879); British patent 953 (March 9, 1878); Revue industrielle, 1878, vol. 7, pp. 222- 224; Engineering, 1878, vol. 26, pp. 63-66; 1881, vol. 32, pp. 251-253, 275-277, 299-302, 326-329, 353-355; Fontaine, op. cit. (footnote 19), pp. 161-166. Two years later, in 1880, Gramme devised his machine auto-excitatrice, which combined both the alternator of 1878 and a 4-pole dynamo within a single frame (figs. 87, 88)."-' Two sizes were manu- factured—a small model weighing 280 kg. and re- quiring 4 hp. to supply 12 "candles," and a large one weighing 470 kg. and requiring 8 hp. to
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