ON THE PSYCHO-PHYSICAL VIEW OF NATUEE. 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 19. 



Fechner'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 anatomicse et physiologicsc,' in 



Weber, see the references given which, in 1831, there appeared bis 



above, vol. i. p. 196, also the present celebrated treatise "Tastsinn und 



volume, p. 31, note. Gemeingefiihl." Joh. Miiller's 'Ver- 



- E. H. Weber published in 1817, gleichende Auatomie des Gesicht- 



' Auatomia comparata nervi sym- sinnes ' appeared in 1826. 

 pathici ; ' in 1820, ' De aure et , 3 By Fechner in his ' Elemente 



auditu hominis et animalium ; ' der Psychophysik' (2 vols., Leipzig, 



from 1827 onward, ' Annotationes 1860). 



