MOTION. 37 



may be said that the developement of electricity is greater 

 when the substances employed are broadly distinct in their 

 physical and chemical qualities, and more particularly in their 

 conducting powers ; but up to the present time the laws gov- 

 erning such developement have not been even approximately 

 determined. 



I have said, in reference to the various forces or affections 

 of matter, that either of them may, mediately or immediately, 

 produce the others ; and this is all I can venture to predicate 

 .of them in the present state of science ; but after much con- 

 sideration I incline strongly to the opinion that science is rap- 

 idly progressing towards the establishment of immediate or 

 direct relations between all these forces. "Where at present 

 no immediate relation is established between any of them, 

 electricity generally forms the intervening link or middle 

 term. 



Motion, then, will directly produce heat and electricity, 

 and electricity, being produced by it, will produce magnetism 

 a force which is always developed by electrical currents at 

 right angles to the direction of those currents, as will be sub- 

 sequently more fully explained. Light also is readily pro- 

 duced by motion, either directly, as when accompanying the 

 heat of friction, or mediately, by electricity resulting from 

 motion ; as in the electrical spark, which has most of the at- 

 tributes of solar light, differing from it only in those respects 

 in which light differs when emanating from different sources 

 or seen through different media ; for instance, in the position 

 of the fixed lines in the spectrum or in the ratios of the spaces 

 occupied by rays of different refrangibility. In the decom- 

 positions and compositions which the terminal points proceed- 

 ing from the conductors of an electrical machine develope 

 when immersed in different chemical media, we get the pro- 

 duction of chemical affinity by electricity, of which motion is 

 the initial source.. Lastly, motion may be again reproduced 

 by the forces which have emanated from motion ; thus, tho 



