362 



GENERAL SCIENCE 



FIG. 244. If you fix your eyes on the two white spaces between the lines the 

 top space will seem to become wider at the ends, and the bottom space 

 wider in the middle. But both are perfectly straight. 



/r\ 



FIG. 245. Which line 

 is the longer? The 

 black line on the right 

 appears longer than 

 the line beside it, but 

 both lines are exactly 

 the same length. 



FIG. 246. This shows how a 

 circle appears to have sides 

 and' corners. These black 

 spots, if looked at intently, 

 seem to have six sides, like 

 a honeycomb, but they are 

 all quite round. 



FIG. 247. There is a blind spot in both your eyes that is to say, part of 

 the eye is blind. You can prove this by closing your left eye and looking 

 at the X witl? your right. Hold the paper a foot away and then draw it 

 towards you. While looking at the X you will see the spot too, but at a 

 certain point the spot will disappear. By drawing it still nearer to you 

 you will bring the spot into view again. 



