MAN'S CO-LABORER. THE DYNAMO 



America by Joseph Henry of Albany who made enor- 

 mous electromagnets, capable of sustaining great 

 weights. One of his magnets, operated by a single cell, 

 was able to lift six hundred and fifty pounds of metal. 



It was this apparatus which was subsequently to 

 make possible the utilization of electricity as a working 

 force, but as yet no one suspected its possibilities in 

 this direction. 



It remained for Michael Faraday, in 1831, to make 

 the final experiment which laid the secure foundation 

 for the new science of electrodynamics. Faraday con- 

 structed a tiny apparatus, consisting of a magnet 

 between the poles of which a metal disk was placed in 

 such a way that it could revolve on an axis, the disk 

 being connected with a wire conveying an electric 

 current. 



The details as to this most ingenious mechanism 

 need not be given here. Suffice it that Faraday demon- 

 strated the interrelations of magnetism and electricity 

 and the possibility of causing a metal disk to revolve 

 through this mutual interaction. In so doing he con- 

 structed the first dynamo-electric machine. In his hands 

 it was a mere laboratory toy, but the principles involved 

 were fully elaborated by the original experimenter, and 

 stated in precise language which modern investigators 

 have not been able to improve upon. 



Several decades elapsed after Faraday's initial ex- 

 periment before the phenomena of magneto-electricity 

 were proved to have any considerable commercial 

 significance. A vast amount of ingenuity was required 

 to devise a mechanism which could advantageously util- 



VOL. VI. 12 [ 



