550 THE PRINCIPLES OF SCIENCE. [ch. xxtv. 



true diamagnet, with its head a north pole and its feet a 

 south pole. The same is certainly true of man as he stands 

 upon the earth's surface, for all tlie tissues of the human 

 body are diamagnetic." ^ The sun's light produces a very 

 quick and perceptible effect upon the photographic plate ; 

 in all probability it has a less effect upon a great variety 

 of substances. We may regard every phenomenon as an 

 exaggerated and conspicuous case of a process vk'hich is, in 

 infinitely numerous cases, beyond the means of observa- 

 tion. 



^ l'hiLosoj[)}M(d Transactions, \m1. cxlvi. j^. 249. 



