FISH PHOTOGRAPHIC EXCURSIONS 171 
a diving-suit, and conceal oneself in the water, as the 
Keartons conceal themselves on land; but even then 
the scope of sub-aquatie photography would be greatly 
limited by the question of light. 
As the nearest approach to fish photography in 
natural environments, I have referred, in the intro- 
duction, to the use of a specially constructed pond. 
Fish photography can also be undertaken with the 
camera above the water; but as the object of such 
work is essentially to see fish as they appear to each 
other, this bird’s-eye view of fishes is only interesting in 
the case of those which live near or on the bottom. 
The difficulty in this form of photography les in 
the fact that the light reflected by the surface of the 
water obscures the fish and fogs the plate. Every angler 
will have noticed that even in a clear, smooth-running 
stream, very little can be seen below the surface, except 
where a tree overhangs the banks. The tree cuts off 
the light from above and the weeds, stones, and fish 
beneath the water become visible. In the same manner 
every pebble on the bottom under a bridge can be 
counted. 
Under certain conditions, even when the light from 
above is not cut off, the observer is able to concentrate 
his attention upon the fish and ignore the light reflected 
from the surface. The camera cannot do this, and 
the greater amount of light reflected from the surface 
fogs the plate before the lesser amount of light re- 
flected from the body of the fish can make any impres- 
