ON THE PSYCHO-PHYSICAL VIEW OF NATURE. 493 



the centre of the Leipzig school of Anatomy, Physiology, 

 and Physics. 1 After having been among the first to 

 import the exact methods of research into physiology, 

 and having carried on a variety of investigations refer- 

 ring to physiological optics and acoustics, 2 he approached 

 the subjective phenomena of sensation : recording, for 

 example, with what degree of accuracy different parts 

 of the surface of the skin on face, arm, leg, &c., per- 

 ceive the distance between two points which touch the 

 skin say the two points of a pair of compasses ; 

 recording also the relation of the smallest increase 

 of any given sensation to the corresponding increase 

 of stimulus. In the latter series of experiments, he 

 arrived at what has been termed 3 Weber's Psycho- 

 physical law. He did not call it so himself ; he simply 

 showed by experiment that in a variety of cases the 

 stimulus had to increase in proportion to its own initial 

 intensity in order to produce a just perceptible increase 

 of sensation. These experiments did not attract much is*. 



Fech tier's 



attention till Gustav Theodor Fechner took them up, Psycho- 

 physics. 



building upon them his celebrated " Principles of Psycho- 

 physics." Before referring more in detail to these, I 

 must mention a third line of reasoning which, as stated 

 above, had a considerable influence on the Leipzig school 

 of Psycho - physics, though probably it had as little 



1 On the labours of the brothers 

 Weber, see the references given 

 above, vol. i. p. 196, also the present 

 volume, p. 31, note. 



2 E. H. Weber published in 1817, 

 ' Anatomia comparata nervi sym- 

 pathici ; ' in 1820, ' De aure et 

 auditu hominis et animalium ; ' 

 from 1827 onward, ' Annotationes 



anatoinicac et physiologicac, ' in 

 which, in 1831, there appeared his 

 celebrated treatise " Tastsinn und 

 Gemeingefiihl." Joh. Miiller's ' Ver- 

 gleichende Anatomic des Gesicht- 

 sinnes ' appeared in 1826. 



3 By Fechner in his ' Elemente 

 der Psychophysik ' (2 vols., Leipzig, 

 1860). 



