THE PERCEPTION OF SPACE. 141 



two forefingers parallel and a couple of inches apart, and 

 transferring the gaze of one eye from one to the other. 

 Then the finger not directly looked at will appear to shrink^ 

 and this whatever be the direction of the fingers. On the 

 tongue a crumb, or the calibre of a small tube, appears 

 larger than between the fingers. If two points kept equi- 

 distant (blunted comjDass- or scissors-points, for exampl*^") 

 be drawn across the skin so as really to describe a pair of 

 parallel lines, the lines will appear farther apart in some 

 spots than in others. If, for example, we draw them hori- 

 zontally across the face, so that the mouth falls between 

 them, the person experimented upon will feel as if they^ 

 began to diverge near the mouth and to include it in a well- 

 marked ellipse. In like manner, if we keep the compass- 



FiG. 51 (after Weber). 



points one or two centimetres apart, and draw them down 

 the forearm over the wrist and palm, finally drawing one 

 along one finger, the other along its neighbor, the appear- 

 ance will be that of a single line, soon breaking into two, 

 which become more widely separated below the wrist, to 

 contract again in the palm, and finally diverge rapidly 

 again towards the finger-tips. The dotted lines in Figs. 

 51 and 52 represent the true path of the compass-points ; 

 the full lines their apparent j^ath. 



The same length of skin, moreover, will convey a more 

 extejusive sensation according to the manner of stimulation. 

 If the edge of a card be pressed against the skin, the dis- 

 tance between its extremities will seem shorter than that be- 

 tween two compass-tips touching the same terminal points.^ 



* The skin seems to obey a different law from the eye here. If a given 

 retinal tract be excited, first by a series of points, and next by the two 



