U N \ V . 



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 heliogravure 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 placed in 



FIG. 7. Showing Boutan's method of operating his third apparatus from a 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 



