, , n\ s\\\ ■>^-\Vv\\\\\\\ , 



Figure 70. — Gramme'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 Tyndall, op. cit. (footnote 72) ; Douglas, op. cit. (footnote 72). 



^"•i Engineering, 1879, vol. 28, p. 102. 



i»3 British patent 2006 (June 5, 1873); Du Moncel, op. cit. 

 (footnote 80), vol. 5, pp. 525-532; Higgs and Brittle, op.' cit. 

 (footnote 72); Fontaine, op. cit. (footnote 19); Dredge, op. cit. 

 ("footnote 78), pp. 275-287. 



386 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



