PHOTOGRAPHY OF AQUATIC ANIMALS. 53 



order to bring the camera to bear on the object to be photographed, it was then 

 necessary to provide a way to determine when the image of the object appeared in 

 the desired position in the finder. This was accomplished by using a metal tube open 

 at both ends, one end of the tube being placed over the ground glass of the finder 

 and the other, which extended above the water, being applied to the eye. The tube 

 excluded the light from the space between the eye of the observer and the finder, 

 while at the same time the water within it was protected from agitation. By this 

 means it was possible to see clearly the image on the ground glass of the finder. 

 It was necessary merely to manipulate the handle controlling the shutter in order 

 to begin and end the exposure. The plate could then be changed by manipulat- 

 ing the rod at the back of the box and another exposure made at once without 

 taking the camera from the x water. Where it was possible to operate near shore, 

 it was unnecessary for the operator to put on the diver's suit or to enter the water. 

 He could set the camera in place from the shore and adjust it or make the exposure 

 while lying upon the bank. Boutan, indeed, made satisfactory photographs of 

 fixed animals in aquaria by immersing this apparatus in an indoor aquarium and 

 operating it by means of a string. By using a very small diaphragm he was able 

 to get clear images of objects at a distance of 15 centimeters from the lens, but 

 this required an exposure of three minutes. He obtained photographs of fish and 

 other mobile forms in the same manner by inclosing the animal to be photographed 

 in a glass globe, which was then immersed in the aquarium at a suitable distance 

 from the lens. The globe served to restrict the movements of the animal. When 

 working in shallow water, he found that the algae which appear everywhere in the 

 submarine landscape were in constant motion whenever there was any movement 

 of the water. It was therefore necessary to restrict operations to those days on 

 which it was perfectly calm. 



In order to obtain photographs at depths at which it was impossible to wade 

 Boutan made use of the diver's outfit. He describes the outfit in detail and the 

 method of using it in a very interesting section of his paper of 1898. The method of 

 procedure was briefly as follows: The boat containing the apparatus to be used 

 (diver's suit, air pumps, and photographic apparatus) was first firmly anchored at the 

 spot selected and held in place by means of cables stretched to the rocks on shore. 

 The photographer then put on the diver's suit and descended to the point selected as 

 the center of operations. He first signaled to an assistant to let down the photo- 

 graphic apparatus, which consisted of the tripod, the box containing the camera, and 

 a weight intended to steady the apparatus. He then sought out the view to be 

 taken and set up the apparatus at his leisure. This accomplished, he opened the 

 shutter of the camera and signaled to the assistant that the exposure was begun. 

 Since it was impossible to use a watch while under water it was necessary that the 

 assistant in the boat above should time the exposure. At the expiration of the 

 time agreed upon the assistant signaled and the photographer closed the shutter. 

 When the weather was good and the sun shining an exposure of ten minutes was 

 necessary with a small diaphragm at a depth of 5 meters. Boutan estimated 

 that at a depth of 10 meters this exposure would need to be more than doubled. 



