82 POPULAR LECTURES AND ADDRESSES. 

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kinetic unit. f It will simplify matters if we think 

 merely of a magnetic force, whether it be due 

 to a steel magnet, or to a wire conveying a 

 current ; and make no distinction so far as 

 measurement is concerned, through the range 

 of the science of magnetism, including electro- 

 magnetism. We shall find that we have the 

 two capital subjects ; electricity and electro-static 

 force one of them : magnetism and electricity 

 in motion through conductors, and magnetic 

 and electro-magnetic force, the other. The first 

 complete method of scientific measurement for 

 any of these subjects was that of Gauss, in his 

 system of absolute measurement for terrestrial 

 magnetism so splendidly realised by Gauss and 

 Weber in their Magnetic Society of Gottingen, 

 which gave the starting impulse for the whole 

 system of absolute measurement as we now 

 have it, throughout the range of electric science. 

 In fact, Weber himself, after realising absolute 

 measure in terrestrial magnetism in conjunction 

 with Gauss, carried it on through the field of 

 electro-magnetism in his Elektrodynamische 



