THIS ELECTRIC LIGHT. 671 



of February a paper from Sir Charles Wheatstone was 

 received, bearing the title, " On the Augmentation of the 

 Power of a Magnet by the reaction thereon of Currents 

 induced by the Magnet itself." Both papers, which dealt 

 with the same discovery, and which were illustrated by 

 experiments, were read upon the same night, viz., the 14th 

 of February. It would be difficult to find in the whole 

 field of science a more beautiful example of the interaction 

 of natural forces than that set forth in these two papers. 

 You can hardly find a bit of iron you can hardly pick up 

 an old horseshoe, for example that does not possess a 

 trace of permanent magnetism; and from such a email 

 beginning Siemens and Wheatstone have taught us to rise 

 by a series of interactions between magnet and armature to 

 a magnetic intensity previously unapproached. Conceive 

 the Siemens armature placed between the poles of a suit- 

 able electro-magnet. Suppose this latter to possess at 

 starting the faintest trace of magnetism; when the arma- 

 ture rotates, currents of infinitesimal strength are generated 

 in its coil. Let the ends of that coil be connected with 

 the wire surrounding the electro-magnet. The infinitesimal 

 current generated in the armature will then circulate round 

 the magnet, augmenting its intensity by an infinitesimal 

 amount. The strengthened magnet instantly reacts upon 

 the coil which feeds it, producing a current of greater 

 strength. This current again passes round the magnet, 

 which immediately brings its enhanced power to bear upon 

 the coil. By this play of mutual give and take between 

 magnet and armature, the strength of the former is raised 

 in a very brief interval from almost nothing to complete 

 magnetic saturation. Such a magnet and armature are 

 able to produce currents of extraordinary power, and if an 



Sabine's statement; still it would be dangerous in the highest 

 degree to depart from the canon, in asserting which Faraday was 

 specially strenuous, that the date of a discovery is the date'of its 

 publication. Toward the end of December, 1866, Mr. Alfred Varley 

 also lodged a provisional specification (which, I believe, is a sealed 

 document) embodying the principles of the dynamo-electric machine, 

 but some years elapsed before he made ' anything public. His 

 brother, Mr. Cromwell Varley, when writing on this subject in 1867, 

 does not mention him (Proc. Roy. Soc., March 14, 1867). It probably 

 marks a national trait, that sealed communications, though allowed 

 in France, have never been recognized by the scientific societies of 

 England. 



