96 FLY FISHING AND SPINNING 



man above the water. This is not so, however, for the rays 

 of light from the fisherman on the bank, say at forty feet 

 distance, would lose nothing in passing through the air till 

 they strike and enter the water (as at b B, Diagram 3) ; 

 they will then only have some two to four feet of water to 

 pass through before reaching the fish. A certain amount of 

 light will be undoubtedly lost, even in this small distance, 

 owing to the density of the water, but the vertical depth 

 of the fish below the surface of any trout stream will never 

 be sufficiently great to prevent all rays reaching it. This 

 density of the water will cause a very rapid diminution of the 

 rays from any sub-aqueous object, as horizontal or vertical 

 distance is attained ; and while objects may, in favourable 

 circumstances, be still visible to the fish twenty-five feet 

 away, in any horizontal direction within the zone of its 

 horizontal sight, they may in calm, still waters be taken as 

 being unnoticeable in ordinary circumstances at a distance 

 of about thirty feet. In rapid running water the rays from 

 any object will be still further lost or deflected by the eddies, 

 etc. 



From my own experience in a diving-dress in the clear 

 waters of the Torres Straits, which were undisturbed by any 

 ripples, eddies, etc., I found that all objects in the horizontal 

 plane were invisible to me beyond a distance of about twenty 

 feet : the head of a shark coming towards me would be 

 visible at about seventeen feet, while its tail would at the 

 same time be quite invisible and lost in the misty wall 

 surrounding me.* It may be, therefore, confidently assumed 

 that the wader, even when faced by the trout, will, as far as 

 his waders are concerned, be unnoticed by the trout at a 

 distance of from twenty-five to thirty-five feet. 



* While this limit to my range of sight may have been due, to a certain 

 extent, to the thick glass of the helmet through which I had to look, the greater 

 part of it would be due to the absorption of light by the water itself. 



