THE EYE 



157 



until the plate is too near the lens even for the distant 

 landscape. There is this great difference between 

 near-sight and far-sight : that in the former accommodation 

 makes matters worse while in the latter it establishes 

 clear vision. 



The sufferer from far-sight gains a satisfactory picture 

 of the distance by using a moderate degree of accommo- 



FIG. 40. (A) suggests the normal eye, focusing parallel rays, that 

 is, rays of distant origin. 



(B) is a near-sighted eye, outline dotted ; it is too deep to focus such 

 rays but adapted to certain rays from near objects. 



(C) is a far-sighted eye, outline dotted, too shallow for any focus until 

 the accommodation power is used. 



dation effort. To read he must redouble the strain. 

 He accomplishes his purpose, but at a cost to his nervous 

 system which is likely to be evidenced through headaches, 

 indigestion, and other disorders. A convex glass sup- 

 plies the extra refraction needed by the far-sighted and 

 relieves him from the necessity of providing it constantly 

 by his own effort. Comparing the near-sighted and the 





