CHAPTER XVI 



PSYCHO-PHYSICS 



Boss, as we have seen, had gone to England in 1900 in 

 hopes of making over his researches on the borderland of 

 physics and physiology to the physiologists ; and he 

 expected to return to continue his physical work, with its 

 many opening perspectives. But the opposition of the 

 physiologists challenged him to his new course of investi- 

 gations. His physical turn of thinking had always repelled 

 him from metaphysical speculation ; and he had not 

 taken much, if any, interest in' experimental psychology. 

 But unexpected results in his investigations made him 

 realise that there were important analogies even in the 

 field of psycho-physics, and these parallels increasingly 

 compelled attention, though for a long time with some 

 reluctance. 



Bose's attention was first attracted to the responsive 

 peculiarities of various forms of ' artificial retina ' which 

 he had constructed. He found that the stimulus of light 

 has not only an immediate effect but also an after-effect ; 

 and that the after-effect of a strong stimulus persists for 

 a longer time than that of a feeble one. He describes very 

 interesting visual analogues where he was actually able to 

 see better when the eyes were shut. He had been observing 

 an experiment of Sir William Roberts-Austen on the 

 quick fusion of metals, where owing to the glare and dense 

 fumes it was impossible to see what happened in the 



