INTELLIGENCE AM) SPECIAL SENSES. 57 



xVt a recent meeting of the Manchester Anglers' Associa- 

 tion, in Enghuul, Dr. A. Hodgkinson gave an address on 

 the " Optics of Angling," which is thus noticed by the 

 '' London Fishing Gazette :'' 



" In considering the subject of angling optics, we arc met, as 

 Dr. Hodgkinson pointed out, by the difficulty that we do not 

 know exactly what the sight of fishes is, but we must assume it 

 to be not much uulike our own, and we are not without grounds 

 for the assumption. By drawings on a blackboard, Dr. Hodg- 

 kinson showed how the eyes of both men and fishes were alike in 

 their main parts, the greatest divergence being that, whereas the 

 optic nerve in man occupies only a small portion of the bi'ain, in 

 fishes it occupies pretty nearly the whole brain ; and we may pre- 

 sume, 'thei-cfore, that the sight of fishes is more sensitive. 



" Dr. Hodgkinson then dealt with the phenomena of the pass- 

 age of rays of light from the rare medium air to the dense me- 

 dium water, and the change in direction that the incident ray 

 undergoes ; he pointed out the fact that under certain conditions 

 an angler on the bank might be invisible to a fish in the stream, 

 but the exultation of the gentlemen assembled was probably 

 damj)ed when they heard that, in order practically to discover 

 the distance they must stand from the water in order to be invis- 

 ible, they must take their height and multiply it by fourteen, 

 which, as an unfortunate angler who was present pointed out, 

 would require him, seeing that he is six feet high, to stand eighty- 

 four feet from the water's edge before he could take advantage 

 of the invisible mantle Dr. Hodgkinson had promised him. The 

 case, however, is not quite so hopeless as this, for, as the doctor 

 pointed out, the water in which the fly-fisher angles is not gener- 

 ally so smooth as a mirror, and in ripple or broken water it is 

 impossible for fish to see the object on two legs that may be on 

 the bank. 



" In fishing for trout, wading in many streams is a necessity, and 



