392 SIGHT. HAWKS. 



i 



Q. Why do OLD people HOLD objects FURTHER 

 OFF, in order to see them better ? 



A. As the distance between the front 

 and back of their eye is not great enough, 

 the reflection of near objects is thrown 

 beyond the ret'ina; therefore, they hold 

 objects a long way off, in order to bring 

 their images forward (so as to cast it on 

 the ret'ina). 



Q. Why are HAWKS able to see such an IM- 

 MENSE way off? 



A. Because they have a muscle in 

 the eye which enables them to flatten 

 their cor'nea, by drawing back the crystal- 

 line lens. 



This muscle is called the " marsupium:" 

 Q. Why can HAWKS not only see such a long 



way off, but also objects within half-an-inch of their 



eye? 



A. Because their eyes are furnished 



with a broad circular rim which confines 



the action of this muscle, and throws the 



cor'nea forward. 



Q. Into how many PARTS may a RAY of LIGHT 

 be DIVIDED ? 



A. Into three parts : BLUE, YELLOW, 

 and RED. 



