384 Fly-rods and Fly-tackle. 



the spectrum while the middle is to them a blank ; their 

 every action in reference to the color of flies negatives 

 this. 



The eye, whether of fish or flesh, is but a lens re- 

 fracting rays of light, and converging them to form a 

 picture on a screen the retina. In this respect, and as 

 far as the mechanical principles of construction are con- 

 cerned, it has its exact counterpart in the camera of the 

 photographer. 



Light is light, and by its aid all animated beings see, 

 and in its absence all alike are blind. The laws of nat- 

 ure operate equally and invariably both above and be- 

 neath the water; and until it is demonstrated to be 

 otherwise, I cannot think that trout see in any different 

 manner, or by different means than do we. There is 

 probably a difference in degree, but I cannot believe in 

 kind. 



Nor is this a matter of mere surmise unsupported by 

 evidence. The eye, whether of fish, flesh, or fowl, up to 

 the point where the image is formed upon the retina, is a 

 mere mechanical arrangement, the effect of which upon 

 light any good optician can compute. That a mechanical 

 arrangement is framed by the hand of Nature instead of 

 by that of man, is sufficient to induce many to believe, 

 and some to insist, that therefore its function must dif- 

 fer in some mysterious and abnormal manner, and un- 

 bridled license is given to the imagination. In this spirit 

 the extent of the visual powers of fish is not unfrequent- 

 ly discussed. 



But in point of fact a lever is a lever, whether it be a 

 crow-bar in the hands of a quarryman, a fly-rod wielded 

 by an angler, or a bone in a horse's leg ; and the action 

 of a lens upon light is but the action of a lens, whether 



