EULOGY ON AMPERE. 141 



Another class of critics embarrassed our associate more seriously. 

 These last acted apparently in a charitable spirit. To believe them, they 

 juvoked with all their hearts, but without hope, the solution of a j^reat 

 difficulty ', it pained them deeply, they said, to see the glory with which 

 these new discoveries would have surrounded the name of Ami>ere 

 vanish so rapidly. This is somewhat the manner in which the insur- 

 mountable difficulty was formulated. Two bodies which separately 

 have the property of acting on a third cannot fail to act on each other. 

 The connecting wkes, according to the discovery of (Ersted, act upon 

 the magnetic needle, then two connecting wires ought to influence each 

 other reciprocally 5 hence, the movements of attraction and repulsion, 

 when brought together, are deductions, necessary consequences, of the 

 experiment of the Danish i^hysicist ; hence, it would be wrong to rank 

 the observations of Ami)^re among the i)rimordial facts which open to 

 science entirely new paths. 



Action and reaction are equal. There was in the phraseology just 

 cited a false air of that incontestible principle of mechanics which misled 

 many minds. Ampere replied by challenging his adversaries to deduce 

 with any degree of plausibility the resultant direction {le sens) of the mu- 

 tual action of two electrical currents ; although he made the demand with 

 much spirit, no one acknowledged himself defeated. 



The infallible means of reducing this violent opposition to silence, of 

 sapping its objections to their foundation, was to cite an example where 

 two bodies which would act separately on a third would, nevertheless, 

 not act on each other. A friend of Ampere remarked, that magnetism 

 exhibited a phenomenon of this kind. He said to the benevolent an- 

 tagonist of the great geometer : •' Here are two keys of soft iron ; each of 

 them attracts this compass ; if you cannot show that, placed near each 

 ther, these keys attract and repel each other, the point of departure of 

 all your objections is false." 



From that moment the objections were abandoned and the reciprocal 

 actions of electrical currents took definitely the place belonging to them 

 among the most beautiful discoveries of modern physics. 



Once disembarrassed of the charges of originality and priority, always 

 more painful when implied than when openly made. Ampere sought with 

 zeal a clear, vigorous, and mathematical theory, which would embrace, 

 under a common head, not only all the phenomena of ordinary magnetism, 

 but also those of electro dynamic phenomena. The investigation bristled 

 with all kinds of difficulties. Ampere overcame them with methods on 

 which the genius of invention shone at every step. These methods will 

 remain as one of the most precious models in the art of investigating 

 nature; of seizing in the midst of the complex forms of phenomena lh(j 

 simple laws which govern them. 



Dazzled by the eclaf, grandeur, and fertility of the law of univcrsa! 

 attraction — that immortal discovery of Newton — persons little conxeisani 

 with mathematics imagine that, in order to introduce the planetarji 



