HENRY AS AN ELECTRICAL PIONEER 331 



The start of commercial electric light and power systems and of 

 electric traction came shortly after the beginnings of the telephone 

 about 1880. These, likewise, built upon Henry's work. Powerful 

 electromagnets are the basis of every generator and of every electric 

 motor and it would be difficult for any one today to construct either 

 a generator or a motor and avoid the ideas which were contributed by 

 Henry. Commutators which appear first in Henry's motor are 

 essential parts of every direct current generator or motor. 



Henry's electric motor was not the first one to be built. Faraday 

 built the first electric motor and it was interesting because it was a 

 continuously rotating device. However, it had no commutator and 

 did not employ electromagnets. Henry's motor was interesting 

 because, while it was a reciprocating device, it was the first to employ a 

 commutator and an electromagnet. A combination of these principles, 

 that is, a rotating motor, electromagnets and commutation gives the 

 basis of the modern electric motor of today. 



Henry's comments in 1831 on his electric motor are interesting. 

 "Not much importance, however, is attached to the invention, since 

 the article, in its present state, can only be considered a philosophical 

 toy; although, in the progress of discovery and invention, it is not 

 impossible that the same principle, or some modification of it on a more 

 extended scale, may hereafter be applied to some useful purpose." ^ 

 Much later, in 1876, he writes: " I soon saw, however, that the applica- 

 tion of this power was but an indirect method of employing the energy 

 derived from the combustion of coal, and, therefore, could never 

 compete, on the score of expense, with that agent as a means of pro- 

 pelling machinery, but that it might be used in some cases in which 

 expense of power was not a consideration to be weighed against the 

 value of certain objects to be attained." * Certainly a prophecy, when 

 we consider today the extent to which this "indirect method of 

 employing the energy derived from the combustion of coal" is utilized 

 because of its convenience for lighting and because of its flexibility for 

 the operation of power units through electric motors. 



Modern electrical systems for power and light would be inoperative 

 without the use of auxiliary circuits and equipment for their proper 

 control. In these, extensive use is made of relays and also of other 

 electromagnetic devices using Henry's magnet principle. 



While every branch of the electric power art is indebted to Henry, 

 the alternating current system now in such general use and universal 

 for long distance power distribution owes him a peculiar obligation. 



* "Scientific Writings of Joseph Henry," 1886, Vol. I, p. 54. 



* "A Memorial of Joseph Henry," 1880, p. 149. 



