THE STORY OF NINETEENTH-CENTURY SCIENCE 



stimuli of the sensations of sight and of hearing, the dif- 

 ferential stimulus bearing always a fixed ratio to the 

 total magnitude of the stimuli. Here, then, was the law 

 he had sought. 



Weber's results were definite enough, and striking 

 enough, yet they failed to attract any considerable meas- 

 ure of attention until they were revived and extended 

 by Fechner, and brought before the world in the famous 

 work on psycho-physics. Then they precipitated a veri- 

 table melee. Fechner had not alone verified the earlier 

 results (with certain limitations not essential to the pres- 

 ent consideration), but had invented new methods of 

 making similar tests, and had reduced the whole ques- 

 tion to mathematical treatment. He pronounced Weber's 

 discovery the fundamental law of psycho -physics. In 

 honor of the discoverer, he christened it Weber's Law. 

 He clothed the law in words and in mathematical for- 

 mulae, and, so to say, launched it full tilt at the heads 

 of the psychological world. It made a fine commotion, 

 be assured, for it was the first widely heralded bulletin 

 of the new psychology in its march upon the strongholds 

 of the time-honored metaphysics. The accomplishments 

 of the microscopists and the nerve physiologists had been 

 but preliminary mere border skirmishes of uncertain 

 import. But here was proof that the iconoclastic move- 

 ment meant to invade the very heart of the sacred ter- 

 ritory of mind a territory from which tangible objec- 

 tive fact had been supposed to be forever barred. 



Hardly had the alarm been sounded, however, before 

 a new movement was made. While Fechner's book was 

 fresh from the press, steps were being taken to extend 

 the methods of the physicist in yet another way to the 

 intimate processes of the mind. As Helmholtz had shown 



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