Figure 62. — Gramme's first commercial dy- 

 namo for electroplating. From Revue indus- 

 trielle, November 25, 1874. p. 406, fig. 5. 



consequences delayed the entrepreneurs for a time. 

 Instead the Societe commissioned the instrument- 

 maker Breguet to make magneto generators with a 

 ring armature in the early 1870's for laboratory and 

 small shop use.^' The experience gained by varying 

 the form of these small magneto generators served as 

 a guide in the later construction of the Gramme 

 dynamo. 



In 1871 Gramme presented to the Academic des 

 Sciences a generator based on Ladd's design but with 

 Gramme's ring armatures instead of Siemens' shuttle 

 armatures. A parallel pair of horizontal bar- 

 electromagnets, one above the other, had ring 

 armatures between the poles at each end of the pair. 

 One ring armature supplied current for the electro- 

 magnets and the other supplied the output current. 

 An article appearing in the Comptes renins brought 

 the new kind of armature to the attention of the 

 scientific world and served to stimulate several 

 investigators to try to determine how the current 

 was induced in it.'- 



Gramme patented in 1872 a machine that combined 

 the use of the ring armature, wire brushes to collect 

 the current from the armature, and field excitation 

 by a magneto, the armature of which was on the 

 same arbor as that of the electromagnet generator. 

 By the end of that year the first commercial Gramme 

 generator appeared on the market (figs. 62, 63). '' 

 While this machine was still based on the design of 

 Ladd's apparatus, the modifications considerably 

 improved the efficiency. Instead of using bar- 

 electromagnets arranged horizontally. Gramme used 

 cylindrical electromagnets and arranged them verti- 



inventions of the 1860's were based on magneto- 

 electric machines of the multiple-disk Woolrich type, 

 although one of the specifications in his patent of 

 February 26, 1867, implied self-excitation.^" As 

 mentioned previously, he patented the ring armature 

 in 1870. 



With the Count d'lvernois as financial backer, and 

 Hippolyte Fontaine as the director, the Societe des 

 Machines Magneto-electriques Gramme was founded 

 sometime during the winter of 1870-1871 to manu- 

 facture a generator with the new type of ring arma- 

 ture; however, the Franco-Prussian war and its 



«» French patent 75172 (February 26, li 

 November 21, 1868, and August 13, 1869). 



additions, 



91 Chromque de I'industrie, 1872, vol. 1, pp. 84, 179-180; 

 Du Moncel, op. at. (footnote 80), vol. 2, pp. 219-222; Alfred 

 N. Breguet, "Gramme's Electro- Magnetic Machine," Engi- 

 neering, 1872, vol. 13, p. 289. 



92 Z. T. Gramme, "Sur une Machine magneto-electrique 

 produisant des courants continus," Comptes rendus, 1871, vol. 

 73, pp. 175-178; Theodose du Moncel, op. cit. (footnote 80), 

 vol. 2, pp. 538-544; "Note sur les courants induits resultant de 

 Faction des aimants sur les bobines d'induction normalement 

 a leur axe," Camples rendus, 1872, vol. 74, pp. 1335-1339; 

 J. M. Gaugain, "Sur les Courants d'induction developpes 

 dans la machine de M. Gramme," Comptes rendus, 1872, vol, 

 75, pp. 138-141, 627-630, 828-831; Engineering, 1871, vol. 

 12, pp. 87, 173. 



93 French patent 87938 (addition of February 27, 1872); 

 Z. T. Gramme, "Sur les Machines magneto-electriques 

 Gramme, appliquees a la galvanoplastie et h. la production de 

 la lumiere," Comptes rendus, 1872, vol. 75, pp. 1497-1500; 

 Chronique de Vindusirie, 1873, vol. 2, pp. 86-87, 99, 223-224. 



380 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



