LOOKING UPWARD IN DUSK AND DARK 45 



the artificial fly than on a bright day with full sunlight. 

 The dull day of milk-and-watery glare makes the water 

 look much clearer and full of light than does the bright day. 



We have seen from previous investigation that trout 

 have a strange power of drawing distinctions of colour, 

 and perhaps of texture, in the dusk and dark, and it may 

 be that the under-water world is then relatively better 

 lighted for the trout than the above-water world is for 

 man. If this were so, it would account for the trout being 

 able to distinguish colours from underneath. 



Years ago I picked up from a pedlar on Ludgate Hill 

 a square of plate-glass mirror about five inches by five, 

 in the hope that by means of it I might be able to get some 

 idea of how an artificial fly looked to a trout. I placed 

 it at the bottom of a large papier-mache basin, and floated 

 flies over it. But though no doubt it gave a fair idea of 

 how a fly looked in point of shape, I soon concluded that 

 its value from the point of view of colour was probably 

 largely discounted by the fact that the mirror reflected on 

 to the underside of the fly light which in quantity greatly 

 exceeded and in quality of colour greatly differed from 

 that which would be reflected by rock or gravel, or sand or 

 green weed. I therefore carried the matter no further, 

 and the mirror went the way of all mirrors. 



Recently, however, a friend in the medical profession 

 procured and sent me a laryngeal mirror, one of those 

 little circular mirrors on a long metal bar, like those by 

 the aid of which dentists manage to see the interiors of the 

 hollow teeth on which they are working, while they are 

 working on them; and he suggested that by means of the 

 mirror I might readily see how the artificial fly looked 

 to the trout. Though it seemed to me that this experiment 

 must be subject to much the same objection as the former 

 one, yet, seeing that the mirror could be adjusted to get 



