10 OBSERVATIONS 



the man, round, or over the corner of the bank, 

 by the aid of the water above C, if both were 

 situated as respectively represented in the dia- 

 gram ; but if the surface of the water should be 

 at IK, (i.e.) about as low as the fish's eye, 

 then he could not see any part of the figure AB, 

 because a straight or unrefracted pencil of light, 

 ACB, would be obstructed by the bank. 



Increased obliquity in pencils of light falling 

 from an object upon a surface of water, is ac- 

 companied by still more rapidly increasing refrac- 

 tion : but the distinctness with which the object 

 is seen ^creases in an inverse proportion. 



The bending or refraction which a pencil of 

 light, as NEOFM (fig. 2), falling very obliquely 

 upon the surface of the water, undergoes before 

 arriving at the eye of a fish, at 0, is suffi- 

 cient to produce very great indistinctness and 

 distortion of the image of MP formed in his 

 eye. 



Perhaps indistinctness of vision may, on other 

 accounts, also take place in the eye of a fish look- 

 ing through air. The crystalline and various 

 other humours may not be capable of such com- 

 prehensive adjustment as would enable him to 

 see so distinctly through air as he can through 

 water. 



But long before a pencil of light as, N E L, 

 becomes horizontal, it will not enter the water at 



