THE CONQUEST OF NATURE 



ize the principle in question for commercial purposes. 

 Indeed the early experimenters did not at once get upon 

 the right track, as their efforts were influenced disad- 

 vantageously by an attempt to follow the principle of 

 the steam engine. Some interesting mechanisms were 

 devised whereby the motion of an armature in being 

 drawn toward an electromagnet could be translated 

 into rotary motion through the use of crank-shafts and 

 even of beams, precisely comparable to those employed 

 in the steam engine. Such devices worked with a com- 

 paratively low degree of efficiency and were totally aban- 

 doned so soon as the idea of getting rotary motion di- 

 rectly from the magnet or armature was made feasible. 

 The names of Saxton, Clarke, Woolrich, Wheatstone, 

 and Werner Siemens are intimately connected with the 

 early efforts at utilization of magneto-electric power. 

 The shuttle-wound armature of Siemens, invented in 

 1854, marked an important progressive step. 



PERFECTING THE DYNAMO 



The first separately excited dynamos were constructed 

 by Dr. Henry Wilde, F.R.S., between 1863 and 1865, 

 and this invention paved the way for rapid progress. 

 In 1866-7 Varley, Siemens, Wheatstone, and Ladd con- 

 structed machines with several iron electromagnets, 

 self -excited, which were described as dynamo-electric 

 machines, a term afterward contracted to dynamos. In 

 1867 Dr. Wilde improved the armature by introducing 

 several coils arranged around a cylinder; the current 

 from a few of the coils was rectified and used 



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