1899.] SELLERS — TRANSMISSION OF ENERGY BY ELECTRICITY. 55 



a misapplication of the word power, a pernicious error is perpetuated 

 *tong after the fallacy is understood." He gave a list of what could 

 be classed as the primary powers as used by man. ''First, water 

 power; second, wind power; third, tide power; fourth, the power 

 of combustion; fifth, the power of vital action," remarking that 

 '•'the power of volcanoes and the internal heat of the earth were 

 as yet unused powers." Beyond these few, he says, ''science gives 

 no indication of any other." He did not mention the direct heat 

 of the sun as a source of power. He, however, remarked that 

 "Gravitation, electricity, galvanism, magnetism and chemical 

 affinity can never be employed as original sources of power; they 

 ■ are at the surface of the earth forces of equilibrium, the normal 

 condition of which must be disturbed before they can manifest 

 power, and then the work they can do is only (approximately) 

 equal to the power which was communicated to them in disturbing 

 their state of rest." 



Electricity is not, he said, in itself a source of power, yet, what 

 is very important from his point of view, "electricity, from its 

 •extreme mobility and high elasticity, affords the means of trans- 

 mitting power with scarcely any loss and almost inconceivable 

 velocity to the greatest distance; a wave of disturbance starting 

 from the impulse given at the battery will traverse the circumfer- 

 ence of the earth in less time than I have been occupying in stat- 

 ing the fact." This is interesting, but we are yet far from lealizing 

 the consummation of this idea. When Prof. Henry uttered these 

 words the electric telegraph had become a public necessity, energy 

 had been transmitted over great distances and people had ceased 

 to wonder. 



"The telegraph," he said, "could not possibly have been in- 

 vented, the most ingenious synthetical mind could not have con- 

 trived the electro-magnetic telegraph, until Galvani and Oersted 

 had made their discoveries." The transmission of power by elec- 

 tricity, however, has been possible, in varying degrees of efficiency, 

 almost since 1832, and yet two years ago, as I said before, I felt 

 that in its highest degree of efficiency I had not the right to say it 

 could be presented, in a satisfactory way, to the American Philo- 

 sophical Society in a manner worthy of its founder, who of all 

 men of his day thought chiefly of the practical side of such a 

 subject. 



When Prof. Joseph Henry spoke of the possibility of transmitting 



