137 



stated in his paper respecting the effect of joining the poles 

 with a good conductor), and it is only when the machines 

 are employed for the production of electric light, or other 

 purpose, where the external resistance is considerable that 

 this electro-mechanical function of the current comes into 

 useful operation. 



The author, before concluding his description of this 

 further development of the principle of electro-magnetic 

 accumulation, considers it a duty he owes to himself as well 

 as to science, that he should not allow to pass unnoticed the 

 views and statements of certain writers respecting the place 

 and value of his investigations in the history of natural 

 knowledge. The peculiar good fortune which enabled him 

 to follow up the discovery of a great principle to such 

 brilliant results has contributed, accidentally in some 

 instances, to establish the idea, that these results are an 

 expansion of Faraday's discovery of magneto-electricity 

 rather than a distinct step in electricial science. A brief 

 glance at the history and progress of electricity and magnet- 

 ism will suffice to show the erroneousness of this view, and 

 also that his discovery bears only the same kind of relation 

 to that of Faraday as that philosopher's discovery does to 

 those of Galvani, Yolta, and Grove in galvanic electricity; 

 and of Oersted, Ampere, Arago, and Sturgeon in electro- 

 magnetism. That the discovery of the indefinite increase of 

 the magnetic and electric forces from q^uantities indefinitely 

 small is a fundamental advance in electrical knowledge, and 

 not simply an expansion of kn own prin ciples or an improvement 

 in a machine, as it has been made to appear by some, is evident 

 from the fact that the principle since its enunciation in 18G6, 

 together with the author's invention of minor and major mag- 

 neto-electric circuits, has been embodied in the machines of 

 different forms constructed by Ladd, Holmes, d'lvernois, 

 Gramme, and others. Moreover, Faraday himself, while on 

 the threshold of his discovery, distinctly negatived its possi- 



