362 THE INTELLECTUAL RISE IN ELECTRICITY. 



The foregoing will suffice to show the remarkable and 

 novel character of the magnetic theory of Descartes. 

 Apparently it seems to have had no other origin than the 

 "scientific use of the imagination," but this is not entirely 

 true. Induction from phenomena forced its way into his 

 reasoning, despite his belief that he was dealing solely with 

 his own intuitions. After he had explained, in his limpid 

 style, the accordance of his hypotheses and the various 

 phenomena of the magnet, which he sums up beautifully 

 in thirty-four aphorisms, he betrays the material mechan- 

 ism which really sets going all this speculation. I shall 

 let him reveal it for himself. 



u Now, if one should stop to consider how iron powder 

 or iron filings thrown about a magnet arrange themselves, 

 many things would be observed confirming the truth of 

 what I have just said." (Observe the fallacy, post hoc, 

 ergo propter hoc.) 4 'For,,,in the first place, it will be seen 

 that the little grains of this powder do not pack themselves 

 together confusedly, but that joining themselves together 

 lengthwise they form filaments, which are as many little 

 tubes, through which the spirals pass more freely than 

 through the air, and which, therefore, may serve to show 

 the path of the spirals after they have left the magnet. 

 But in order that the eye may recognize the curving of 

 these paths the filings should be strewn upon a smooth 

 surface, in which the globular magnet is half buried, so 

 that its poles are in the same plane, as globes are supported 

 in horizon circles; then on that surface the filings will 

 arrange themselves in lines showing exactly the paths 

 which the spirals take around the magnet and also around 

 the earth." 



Then he continues further and explains how the filings 

 group themselves around the poles of the two magnets 

 when attraction or repulsion takes place. 



He had seen all that Cabaeus did not see. He had recog- 

 nized the whole magnetic spectrum, the complete magnetic 

 curves, and that the lines of force or paths along which the 



