PHOTOGRAPHY OF AQUATIC ANIMALS, 57 
front he made the exposure. The plate was then changed and several exposures 
made in succession. The screen was useful as affording a contrasting background 
but was not considered necessary, since very clear negatives were obtained of fish 
viewed against the sand or ooze bottom. One of the photographs of fish taken 
against a screen background is reproduced by heliograyvure in Boutan’s memoir of 
1898. Though the fish were in motion, the outlines of most of them appear sharp 
against the screen, evidence that the picture was instantaneous. The fish are, 
however, unfortunately almost wholly lacking in detail. The time of the exposure 
is not stated, but it was clearly too short to give detail in the shadows. 
In figure 7 is shown a method adopted by Boutan for operating the camera 
from a boat by means of a string. In this case the apparatus was first placéd in 
Fic. 7.—Showing Boutan’s method of operating his third apparatus froma boat by means 
of a string. A diver is being photographed. (Copy of fig.8 in Boutan, 1898.) 
position by the diver, who then withdrew to the distance for which the camera was 
focused. The operator, who could observe the procedure from the boat, then pulled 
the string. The resulting picture, which is reproduced in Boutan (1898), is excellent. 
Subsequently exposures were made from the surface by using a shutter controlled 
by an electro-magnet. 
BOUTAN’S METHODS OF ARTIFICIAL ILLUMINATION. 
Besides his camera, Boutan (1893) describes an apparatus for using a mag- 
nesium flash-light beneath the surface of the water. He succeeded subsequently 
in taking good instantaneous pictures at a depth of 3 meters without artificial 
