58 SUPPLEMENT TO THE BOOK OF THE BLACK BASS. 



by means of an ingeniously constructed tank Dr. Hodgkinson 

 showed not only what the angler looked like to the fish when he 

 waded, but how his aspect was affected by the color of the bot- 

 tom of the river, and that of such cover as there might be on 

 the bank. The rather startling announcement was made and 

 demonstrated, that while the wader was duplicated so far as his 

 legs were concerned, another pair appearing upside down on the 

 actual legs, the man's body, if visible at all, was far away from 

 the legs, and overhead, where, if we put ourselves in the position 

 of the fishes, we should expect to see nothing but sky. No fish 

 then ever saw a wader with his two halves united, and whether 

 its feeble brain can ever connect together the two distinct objects 

 the body up in the air and the legs down in the water is ex- 

 tremely doubtful. 



' ' The tank by which Dr. Hodgkinson was enabled to demon- 

 strate his theories was made so that from one end the observer 

 could, by directing his vision from various depths of water, al- 

 ways look through a slip of glass placed at right angles to the 

 point toward which he looked. In this way, and by use of a lit- 

 tle figure to represent a man, the point where invisibility begins 

 (four degrees) could be clearly seen, as well as the effect which 

 the water has of apparently lifting the object much above the 

 position which it occupies." 



SENSE OP HEARING. 



It is the rule among physiologists to say, that while fishes 

 can hear sounds produced in the water, they are incapable 

 of hearing those produced in the air, and even to limit their 

 capacity for hearing accurately those produced in the water. 

 Take this, for example, from Mr. Hugh Owen, in " Land 

 and Water : " 



" It is exceedingly doubtful if fish possess the faculty of hear- 



