WHAT THE FISH SEES 



eighty-three degrees. It is as if he saw out 

 through a port-hole surrounded by a mirror. 



The diagram (Figure 14) shows this clearly. 

 F represents a fish near the bottom. He can see 

 out till he reaches the hne AF or A' F. Beyond 



98/2% Light Entera Water j. 



•A 



Fig. 14. DIAGRAM OF FISH'S WINDOW 



these lines he sees the reflected bottom. Suppose 

 there is an object at B. The fish can see this di- 

 rectly through the water in a straight line, but he 

 will also see this at B' reflected against the under 

 side of the surface. The same is true of an object 

 at A. A fly below the surface beyond A or ^4' is 

 seen directly and also its reflection against the 

 surface. 

 Light entering the water at different angles does 

 [ 49 ] 



