PHOTOGRAPHY OF AQUATIC ANIMALS. 67 
rapidly more distinct as they approach. Into them they vanish suddenly as they 
recede. 
Subaquatie photographs show the same lack of distance that so impresses the 
eye. Thus in the photographs shown on plate 1 the distance appears indistinct, 
partly because the objects in it are out of focus, but chiefly because they are enveloped 
in the bluish translucence mentioned above. It is therefore impossible under water 
to photograph objects at any considerable distance. To the photographer who 
is unfamiliar with the aspect of the subaquatic landscape this lack of distance in 
photographs of it seems a defect. But to the artist or naturalist who has seen things 
as they look to one beneath the water it is really a merit, since it shows these thin 
as they are. 
The source of this lack of distance is probably double. It is due in part to the 
fact that even the clearest water contains very many bodies in suspension, living 
organisms, and inorganic and organic particles. These, like dust in the atmosphere, 
interfere with distance vision. It is due also in part to the reflection of the light 
from the surface of the water. Light which has entered the water from above 
strikes upon and illuminates various bodies beneath the surface. From these a part 
of it is reflected to the surface of the water again. If it strikes the surface at an 
angle of more than 48° 35’ with the vertical it is totally reflected and passes again 
into the water. Here it again strikes some submerged body and is again in part 
reflected to the surface and here again in part re-reflected. Thus shallow water is 
traversed in every direction by beams of light which intercross at every angle. 
These illuminate the opaque particles floating in the water and are deflected by 
reflection. They are also deflected by refraction through the more transparent 
organisms. In this way probably is produced the background of bluish-white 
opalescence which characterizes the subaquatic landscape. To one who knows 
that landscape, the background, hiding many mysteries, adds to it character and 
beauty. A photograph that failed to show it would be lacking in character. Boutan 
(1893), who discusses this subject, made use of a blue color screen and believed that 
he obtained greater distance in his subaquatic pictures by this means. In his more 
recent work (1900, p. 283) he abandoned the use of the color screen. He obtained 
clear pictures of near objects by using a shade above the lens, as already described. 
Boutan appears never to have obtained clear pictures of more distant objects. The 
writer has made use of an ordinary yellow color screen (graphic no. 3) but is unable 
to say with certainty that it adds anything to the distance in his pictures. The 
subject needs further study. 
A second characteristic of the subaquatic photographs that strikes the photog- 
raphers unpleasantly is their flatness. Objects of all sorts appear lacking in thick- 
ness or rotundity and do not cast abrupt or heavy shadows. This peculiarity the 
writer believes to be due to the reflection of light from submerged objects into the 
water at the water’s surface. Light thus reflected on the subaquatic object from 
the bottom beneath and from the surface above and at all angles takes out of it 
much of its roundness. It takes out the shadows very much asa photographer in 
his studio may take them out by a suitable adjustment of reflecting screens. Along 
with this flatness of the individual objects in the subaquatic photograph there is 
abundance of contrast between different parts, as may be seen in plate 1. 
m4 
gs 
