,^'^-:fj^' -^jj '.a*iJ-«^^fsCJ> 



iniHjNinuiUii^ 



Figure 65. — Gramme's first form of the type 

 d'atelier dynamo for electroplating. From 

 Revue industrielle, November 25, 1874, p. 407. 



Figure 64. — Gramme's arc-light dynamo, 1874 

 version. From Revue industrielle, November 

 25. 1874, p. 408. 



resistance with coarse wire on the armature for 

 electrochemical purposes, and one of high resistance 

 with fine wire on the armature for use with arc lights. 

 The high-current electrochemical machine had two 

 armatures on a common axis and four electromagnets. 

 It weighed about 750 kg., measured 0.8 meters 

 square by 1.3 meters high, and required 175 kg. of 

 copper wire. When driven by a 1-hp. engine at 

 300 r.p.m. it produced about 150 amperes at 2 

 volts, which implied an efficiency of about 40 percent. 

 The high-voltage arc-light machine used three 

 armatures and six electromagnets. It weighed about 

 1,000 kg. and measured 0.8 meters square and 1.25 

 meters high. The electromagnets required 250 kg. 

 of copper wire and the armature required 75 kg. 

 of copper wire. When driven by a 4-hp. engine at 

 300 r.p.m. the machine produced a light of about 

 850 Carcel units, about four times as much as the 



Figure 66. — Gramme's first form of the type 

 d^atelier dynamo for arc lights. From Revue 

 industrielle, November 25, 1874, p. 409. 



382 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY .\ND TECHNOLOGY 



