446 FRAGMENTS OF SCIENCE 



mained separate, had no circuit through which it could 

 pass. The current here evoked subsides immediately as 

 heat; this heat being the exact equivalent of the excess 

 of effort just referred to as over and above that necessary 

 to overcome the simple weight of the coil. When the 

 coil is liberated it falls back to the table, and when its 

 ends are united it encounters a resistance over and above 

 that of the air. It generates an electric current opposed 

 in direction to the first, and reaches the table with a di- 

 minished shock. The amount of the diminution is accu- 

 rately represented by the warmth which the momentary 

 current develops in the coil. Various devices were em- 

 ployed to exalt these induced currents, among which the 

 instruments of Pixii, Clarke, and Saxton were long con- 

 spicuous. Faraday, indeed, foresaw that such attempts 

 were sure to be made; but he chose to leave them in the 

 hands of the mechanician, while he himself pursued the 

 deeper study of facts and principles. "I have rather," he 

 writes in 1831, "been desirous of discovering new facts 

 and new relations dependent on magneto-electric induc- 

 tion, than of exalting the force of those already obtained; 

 being assured that the latter would find their full devel- 

 opment hereafter." 



For more than twenty years magneto -electricity had 

 subserved its first and noblest purpose of augmenting our 

 knowledge of the powers of nature. It had been disco v 

 ered and applied to intellectual ends, its application to 

 practical ends being still unrealized. The Drummond 

 light had raised thoughts and hopes of vast improvements 

 in public illumination. Many inventors tried to obtain it 

 cheaply; and in 1853 an attempt was made to organize 

 a company in Paris for the purpose of procuring, through 





