WHAT THE FISH SEES 



at the surface of the water and let a ray of light, 

 A-B, reach the surface at B. Draw a line parallel 

 to the surface of the water from A to the line 

 H-B, which is perpendicular to the surface of the 

 water. Divide this line into three equal parts. 



FIG. 13. REFRACTION OF LIGHT ENTERING WATER 



Extend the line H-B to intersect the circle below the 

 surface of the water. Take a length equal to two 

 of the parts into which A-H was divided and draw 

 a line parallel to the surface of the water from the 

 circle to the extended line H-B, equal in length to 

 two of these parts. This is the line C-G. Join 

 C and B. This will give the direction of the beam 

 of light after it has entered the water. The relation 

 of the length of the line A-H and C-G to each other 



[ 47 ] 



