252 THE WONDERFUL HOUSE THAT JACK HAS 



plains why many persons are obliged to put on glasses 

 at about the age of forty-five, for the lense of the eye 

 has become so inelastic it cannot be controlled by the 

 muscles as it formerly was. Complete rest from close 

 work will sometimes cure cases of nearsightedness at 

 the beginning, and glasses will usually correct those 

 that are not curable by rest. Whether the trouble is 

 temporary or permanent, an oculist should be con- 

 sulted, for the child's future comfort and working power 

 are deeply concerned. 



Farsightedness is a defect of the eye exactly the op- 

 posite of nearsightedness. In this the eyeball is so 

 flat or shallow that, in spite of the assistance of the 

 muscles of accommodation, the rays of 

 light reach the retina before being fo- 

 cused, as seen in the cut. On this 

 account, vision is blurred and indistinct. 

 A farsighted person does not see clearly 

 and easily at any distance. Street signs 

 are not discerned readily, written work 

 on the blackboard is made out with 



Parallel Rays fo- 8 reat difficult y> Sma11 ^P 6 Cannot be 



cased behind the re ad quickly or accurately, nor can dis- 



Retina. . 



tant objects be seen as well as by 

 others who have properly formed eyes. In farsighted- 

 ness the lines on the eye-test cards in common use 

 cannot be read at the ordinary distances. If convex 

 glasses placed before such a person's eyes improve the 

 vision, that is good evidence of farsightedness. 



