1879.] on the Eleclric Lhjlit. 5 



facts aiul new rciliitions dcpciulont on niagncto-olcctric induction tliau 

 of exalting the force of tliose already obtained ; being assured that tho 

 latter would tind their full development hereafter." 



This fuller development was aimed at by Pixii, Clark, Saxton, 

 and others, who caused magnets to rotate near coils of wire, or coils 

 of wire surrounding iron cores to rotate near the poles of powerful 

 steel magnets. The presence of the iron cores, as shown by Faraday, 

 greatly intensified the action, the play of which was this : — When the 

 coils aj^proached the poles of the permanent magnets, currents were 

 excited in one direction : when they retreated from the poles, currents 

 were excited in the opposite direction. On passing a pole, therefore, 

 a reversal of the current always occurred in the coil. To gather up 

 these opposing currents, and send them in a common direction, an 

 arrangement called a commutator was associated with the magneto- 

 electric machine. I have here a model of an old Saxton machine 

 with which Faraday used to illustrate what were then considered tho 

 larger phenomena of induced currents. It was considered a great 

 result when half an inch of exceedingly thin platinum wire, inclosed 

 in a glass tube to protect it from air currents, was caused to glow. 

 In 1853 I had the pleasure of witnessing, in company with M. Biot 

 and Professor Magnus, the performance of the first Euhmkorff's 

 machine, which you know is a generator of Faraday's electricity, and 

 I well remember the ecstasy and surprise of the grand old man, evoked 

 by eifects which we should now deem utterly insignificant. Thus 

 science grows. Forgetting, as it were, the things which are behind, 

 it reaches ever forward to the things which are before. In connection 

 with the development of the Kuhmkorff coil, besides Euhmkorff 

 himself, Apps in this country, and Ritchie in America, are especially 

 deserving of honourable mention. 



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 discovered and api^lied to intellectual ends, its 

 api)lication to practical ends being still to be realized. 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 the decomposition of water by a powerful magneto- 

 electric machine constructed by M. Nollet, the oxygen and hydrogen 

 necessary for the lime light. The experiment failed, but the apparatus 

 by which it was attempted suggested to Mr. Holmes other and more 

 hopeful applications. Abandoning the attempt to produce the lime 

 light, with persevering skill Holmes continued to improve the appa- 

 ratus and to augment its power, until it was finally able to yield a 

 magneto-electric light comparable to that of the voltaic battery. 

 Judged by later knowledge, this first machine would be considered 

 cumbrous and defective in the extreme ; but judged by the light of 

 antecedent events, it marked a great step forward. 



Faraday was profoundly interested in the growth of his own 



