454 FRAGMENTS OF SCIENCE 



of February a paper from Sir Charles Wheatstone was re- 

 ceived, bearing the title, **0n 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 in- 

 teraction 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 small beginning Siemens and Wheatstone have 

 taught us to rise by a series of interactions between mag- 

 net and armature to a magnetic intensity previously un- 

 approached. Conceive the Siemens armature placed be- 

 tween the poles of a suitable electro- magnet. Suppose 

 this latter to possess at starting the faintest trace of mag- 

 netism; when the armature rotates, currents of infinitesi- 

 mal 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, aug- 

 menting 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 immedi- 

 ately brings its enhanced power to bear upon the coil. 



of the dynamo-electric machine, but some years elapsed before he made any- 

 thing public. His brother, Mr. Cromwell Varley, when writing on this subject 

 in 1867, does not mention him (Proc. Eoy. 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. 



