334 Dr. C. William Siemens [March 12, 



WEEKLY EVENING MEETING, 



Friday, March 12, 1880. 



The Ddke of Northumbekland, D.C.L. LL.D. Lord Privy Seal, 

 President, in the Chair. 



C. William Siemens, Esq. D.C.L. LL.D. F.E.S. MM.I. 



Tlie Dynamo-Electric Current and some of its Applications. 



(Abstract.) 



The lecturer commenced with a reference to Faraday's great dis- 

 covery of the magneto-electric or induced current, which was first 

 shown to the members of the Koyal Institution in 1831. So slight 

 and instantaneous was the current, that although Faraday had from 

 a priori reasoning arrived as early as 1824 at the conclusion that such 

 a current must be set up in a coil surrounding an armature, when the 

 latter was forcibly severed from a permanent magnet, seven years 

 elapsed before he could detect that current with the instruments then 

 at his command. 



It was further shown that although each induced current was feeble 

 and only instantaneous in its action, it differed from a galvanic current 

 in the important particular that it was the immediate outcome of the 

 expenditure of mechanical force, and that by repeating the operation of 

 severance by suitable mechanical arrangements a rapid succession and 

 an aggregation of these currents could be directed through a metallic 

 conductor, and produce in it all the phenomena of a continuous current 

 of great magnitude. The single current revealed by Faraday's original 

 experiment might be likened to the single drop of rain, which, though 

 impuissant by itself, was, when repeated often enough in its fall upon 

 an elevated plateau, capable of giving rise to streamlets and streams, 

 until at last a mighty river and a source of power, such as the Falls 

 of Niagara, might be produced. It was shown by experiment that the 

 single current resulting from the forcible severance of an armature 

 from its magnet was capable, if directed through the coils of another 

 armature in contact with its own magnet, of effecting its severance 

 from the same ; and that the force expended bore a definite relation 

 to the force obtained in moving the second armature. In viewing 

 this experiment by the light of advanced science it followed that in 

 this way the conversion of mechanical force into electric current, and 



