THE SENSES OF A TROUT 



91 



therefore, subtends an angle of 96 degrees in every upward 

 direction is confined the view of all objects within the 

 180 degrees vertically above the water. In other words, 

 the trout sees, as it were, all objects above the surface of the 

 water within an arc of about half that in which these 

 objects really exist, and consequently, the comparative 

 size of these objects must be relatively smaller in view of 

 their being cramped into its smaller field of vision. 



ZONE OF 

 I NVISIBI LITY 



40' 



DIAGRAM i. 

 A B C D, horizontal plane of trout's vision ; 



E T , trout ; 

 D A C B, horizontal zone of trout's sight. 



In order to make this perfectly clear to my readers, I 

 have shown two diagrams. 



In Diagram 2, E is the eye of the fish, from which rises 

 a vertical cone E A, E C, E B, E D, the sides of which cut 

 the surface of the water as shown at A B C D. 



All rays of light from objects above the water which 

 reach the trout at E must enter the water within the circle 



