38 THE WAY OF A TROUT WITH A FLY 



appreciate its colour, tone, or texture in any direction. 

 The light reflected from the bottom, gravel, rock, or weed, 

 might be enough. We do not know. 



I was given the privilege, some few years ago, by Dr. 

 Francis Ward, the author of " Marvels of Fish Life," of 

 spending some hours in his underground observation 

 chamber built below water-level on the side of an artificial 

 pond with plate-glass sides cutting off the water from the 

 chamber; and with the assistance of Mr. H. T. Sheringham, 

 the Angling Editor of the Field, I made some brief experi- 

 ments in the direction of trying to divine how trout see 

 the fly, whether floating or sunk. 



The pond was a cement construction, lined at bottom 

 with rock and pebble, but showing from the darkened ob- 

 servation chamber in one side a far side of bare cement. The 

 water came flush with the top of the glass window. The 

 first thing that struck me was that the whole cup of the 

 pond seemed reflected upside down except for a little semi- 

 circle of light just above my head, and as one looked up 

 into the semi-circle of light it seemed as if one were gazing 

 into a big ball of water with a little round hole of rainbow 

 light at the top, and except at this hole the sky was cut off 

 by a sort of mirror, like plate-glass. But the tank was full 

 of light, reflected from the bottom and no doubt back 

 again from the mirror made by the underside of the 

 surface. The semi-circle, of course, indicated by its edge 

 the margin beyond which rays from above proceeding in 

 the direction of the observer's eye ceased to penetrate the 

 surface. I believe that rays striking the water at an angle 

 of more than 48 degrees to the perpendicular above the 

 eye of the observer will be reflected back skywards and 

 substantially do not penetrate. In the same way if one 

 looks beyond the edge of the semi-circle — i.e., outside the 

 angle of 48 degrees — one does not see through the surface, 



