DESCARTES' THEORY OF MAGNETISM. 359 



the sun is obvious. The difference is the substitution of 

 Descartes' whirling matter, mechanically produced, for 

 Kepler's whirling filaments magnetically produced. 



Among the small filings which are ground from the 

 revolving spheres by friction, are many which are com- 

 pelled to escape through the interstices between the whirl- 

 ing particles, and these consequently are molded or shaped 

 into the form of spirals. To the movements of these spiral 

 particles through the pores or conduits of bodies adapted 

 to receive them are due magnetic and electric phenomena. 

 These conduits are shaped to receive the spiral particles, 

 and extend through the bodies possessing them in a direc- 

 tion parallel to an axis. The spirals which can enter at 

 one end of the conduits cannot enter at the other end 

 apparently on the principle that a right hand threaded 

 screw cannot enter a left hand threaded nut ; and also 

 because, in the conduits, there are delicate protruding 

 branches which allow the spirals to bend them freely, 

 while moving in one direction, but become rigid and op- 

 pose their passage while moving in the other something 

 like the converging wires in an old-fashioned mouse-trap. 

 The result is that the spirals, say from the North part of 

 the heavens, can enter the conduits suitable to them at 

 the South end of the stone, pass through these passages 

 to the North* end, and then returning enter the South end 

 again forming a whirlpool through and round the stone. 

 Similarly, the spirals from the South part of the heavens 

 can enter the conduits suitable to them at the North end 

 of the stone and, in like manner, form a whirlpool. 



In other words, Descartes plainly sees that there is a 

 force, not merely radiating from the magnet poles, as 

 Cabseus supposed, but traversing the stone from pole to 

 pole in one direction and then traversing the external 

 region around the stone from pole to pole, in the opposite 

 direction. His spirals whirling about under that in- 

 fluence, were merely a device to render its effect think- 

 able just as were Faraday's equally imaginary lines of 



