. Bulletin. Science. , , n\ s\\\ â >^-\Vv\\\\\\\ , Figure 70.âGramme's 1877 type d'atelier dynamo as driven by a steam engine. From Revue industrielle, May g, 1877, p. 182. instead of 50 percent (fig. 72).'°" With such examples, a new phase in electrical technology seemed to be opening. The introduction of the Gramme dynamo into commerce and industry had repercussions in both Europe and America. As mentioned earlier, the firm of Siemens and Halske had exhibited the drum armature in a magneto detonator for mines and in an alternator excited by a separate magneto generator at the Vienna
. Bulletin. Science. , , n\ s\\\ â >^-\Vv\\\\\\\ , Figure 70.âGramme's 1877 type d'atelier dynamo as driven by a steam engine. From Revue industrielle, May g, 1877, p. 182. instead of 50 percent (fig. 72).'°" With such examples, a new phase in electrical technology seemed to be opening. The introduction of the Gramme dynamo into commerce and industry had repercussions in both Europe and America. As mentioned earlier, the firm of Siemens and Halske had exhibited the drum armature in a magneto detonator for mines and in an alternator excited by a separate magneto generator at the Vienna Exhibition of 1873 (fig. 74). A few units with a drum armature were made in the next few years for commercial use, but these, while comparing very favorably with the Gramme dynamo, did not really enter commerce until 1877, after the W" Fontaine, op. cit. (footnote 12), pp. 89, 109; op. cit. (foot- note 19), pp. 127-128; Alfred N. Breguet, "Notes of Experi- ments on the Electric Currents Produced by the Gramme Magneto-Electric Machine," Reports of the British Association for the Advancement of Science, 1874, vol. 44, pp. 33-34; L'Rlus- tration, 1933, vol. 186, p. 411; Engineering, 1879, vol. 28, pp. 416-418. reports of Tyndall and Douglass'"' were published. In the following two years the English Siemens firm sold more than £60,000 worth of these units.'"^ It was probably because of this increasing competition that Gramme countered with his new type d'atelier model. The commercial Siemens machine of the late 1870's (figs. 15-11) had about the same external appearance as the machine displayed at the Vienna Exposition.'"^ As with Gramme's early dynamos, it was based on the Ladd machine. A pair of flat bar-electromagnets was placed horizontally, and the axis of the armature was perpendicular to the plane of the electromagnets instead of lying in it, as in Gramme's type d'atelier. Since the electromagnets were placed close together, "1 Tynd
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