342 GREAT MEN OF SCIENCE 



abandoned these mechanisms almost entirely, and only re- 

 tained the equations, whereby he reverted completely to the 

 mode of thought of Faraday, who regarded his lines of force 

 simply as pictures of unknown states of a medium filling 

 space. Hence Maxwell himself says that he has put Fara- 

 day's ideas into a mathematical form. In the two volumes 

 of his book On Electricity and Magnetism which appeared in 

 1873, he by no means put the special results of his own dif- 

 ferential equations in the forefront, but developed the then 

 existing body of knowledge of electricity and magnetism in 

 such a way that the statement of it is connected as far as 

 possible with Faraday's conceptions, and hence with his own 

 equations; which, however, only appear towards the end of 

 the work and are almost hidden from sight. The special 

 features of Maxwell's work could only take full effect after 

 their experimental confirmation by Hertz.^ 



Nevertheless, even before this. Maxwell's work resulted in 

 Faraday's idea of lines of force being everywhere accepted, 

 and hence also by technical workers. This was all the more 

 important, since Faraday's induction had found increasing 

 application in the production of strong electric currents, 

 particularly for lighting purposes; for the 'dynamo-electric' 

 principle of Siemens had shown us how to replace the 

 inconstant steel magnets of 'magneto-electric' machines by 

 electro-magnets, which were increased in strength by the 

 induced current itself (i860). What then was still wanting, 

 as compared with the present-day perfection of dynamos and 

 electric motors, was the means of finding the best shape for 

 the iron and copper circuits of these machines; and the way 

 to this, simple but long overlooked, was finally indicated by 

 Faraday's line of thought. The unnecessarily long limbs of 

 the electro-magnets disappeared, and the modern compact 



1 Hertz was also the first who was able to express clearly these special 

 features, together with the equations, free from all superfluous matter, 

 after the natural phenomena themselves had shown the way. 



