ILLUSIONS OF THE SENSES 



153 



Thus, in Fig. 25 a thin vertical line stands upon a thick hor- 

 izontal one ; although the two lines are of precisely the 

 same length, the vertical one 

 seems to be considerably longer 

 than the other. 



In Figs. 26 and 27 a series 

 of vertical and horizontal lines 

 are shown, and in both forms the 

 space that is covered seems to 

 be longer one way than the other. 

 As a matter of fact the space in 

 each case is a perfect square, 

 and the apparent difference in 

 width and height depends upon whether the lines are ver- 

 tical or horizontal. 



Advantage is taken of this curious illusion in dec- 

 orating rooms and in selecting dresses. Stout ladies of 

 taste avoid dress goods having horizontal stripes, and 



Fig. a S . 



Fig. 26. 



Fig. 27. 



ladies of the opposite conformation avoid those in which the 

 stripes are vertical. 



But the greatest discrepancy is seen in Figs. 28 and 29, 

 the middle line in Fig. 29 appearing to be much longer 

 than in Fig. 28. Careful measurement will show that they 

 are both of precisely the same length, the apparent differ- 



