390 FAB SIGHT. 



Q. What is the use of DOUBLE CONCAVE 

 SPECTACLE glasses ? 



A. Near-sighted spectacles cast the 

 reflection further back; and the image 

 (being thrown upon the ret'ina) becomes 

 visible. 



Q. Why are OLD people FAB-SIGHTED ? 



A. Because the humours of their eyes 

 are dried up by age, and the COR'NEA 

 sinks in, or becomes flattened. 



Q. Why does the FLATTENING of the COR'NEA 

 prevent persons seeing objects which are NEAR ? 



A. As the cor'nea is too flat, the 

 image of any near object is formed behind 

 the RET'INA of the eye, and is not seen 

 at all. 



The reflection is made at DE, 

 instead of at AB C (the retina). 



Q. What sort of GLASSES do OLD people 

 WEAR ? 



A. As their cor'nea is not sufficiently 

 convex, they must use double convex 



