330 DYNAMO-ELECTRIC MACHINE. 



the foundation of a new and important branch of 

 industry, and has exerted and still continues to exert 

 a stimulating and transforming influence in all depart- 

 ments of technology, I mean the invention of the 

 dynamo-electric machine. 



As early as the autumn of 1866, when I was 

 intent on perfecting electric exploding apparatus with 

 the help of my cylindrical inductor, the question 

 occupied my mind, whether it would not be possible 

 by suitable employment of the so-called extra- current, 

 to considerably intensify the induction - current. It 

 became clear to me, that an electro-magnetic machine, 

 whose working power is very much enfeebled by the 

 induced currents arising in its coils, because these 

 induced currents considerably diminish the efficiency 

 of the source of electricity, might conversely strengthen 

 the force of the latter, if it were forcibly turned in 

 the opposite direction by an external force. This 

 could not fail to be the case, because the direction 

 of the induced currents was at the same time reversed 

 by the reversed movement. In fact, experiments 

 confirmed this theory, and it appeared that there 

 always remains sufficient magnetism in the fixed 

 electro-magnets of a suitably contrived electro-magnetic 

 machine to produce the most surprising effects by 

 gradually strengthening the current generated by the 

 reversed rotation. 



This was the discovery and first application of 

 the dynamo-electric principle underlying all dynamo- 

 electric machines. The first problem, which was 



