56 



BULLETIN OF THE BUREAU OF FISHERIES. 



This apparatus, which used plates 18 by 24 cm. (approximately 7 by 9 inches), 

 was so heavy that it required three men to handle it easily in air. On shipboard it 

 was handled by a tackle and swinging boom. It was first lowered into the hold, 

 which could be closed light tight. There the plates were put into the plate holder and 

 this was set at the division of the scale previously decided upon. The box was then 

 closed water-tight by screwing the cover in place. To remove the moisture from 

 the air within the box and thus prevent its condensation on the lens and other parts 

 within, a wide-mouthed bottle containing quick lime was kept in the box during 

 the intervals when it was not immersed. The apparatus was then hoisted from the 

 hold, swung outboard and lowered to the operator, who had meantime descended in 

 the diving suit and selected the point at which the photograph should be made. It 

 was not very difficult for the operator to handle the apparatus w r hen it was sub- 



FIG. 6. Showing Boutan's method of obtaining instantaneous photographs of fish with his third ap- 

 paratus. (Copy of fig. 7 in Boutan, 1898.) 



merged, since it was then buoyed up by the water. It was found easier to move it 

 about when it was suspended by means of a rope to a cask floating at the surface. 

 The method of using the camera for photographing fish is shown in figure 6. 

 The camera, previously set for objects at a distance of 2.5 meters, was placed on 

 a sand bottom at a depth of 3 meters. Here it was either allowed to rest on 

 the bottom on the legs attached to it or was supported above the bottom on a 

 heavy, four-legged iron frame. The camera rested on a platform within this frame 

 and the platform might be so adjusted that the camera could be set at various 

 heights and pointed at various angles up or down. At a distance of 2.8 meters 

 from it was set up obliquely a large white screen of painted canvas stretched on an 

 iron frame provided with feet. This screen served as a background for the fish. 

 To attract the fish the operator then placed in front of the screen at a distance of 

 about two meters a bait of crushed sea-urchins and annelids. He then pointed the 

 camera by means of the sight on top and waited until the fish, attracted by the 

 bait, were in such a position as to be in focus, when by means of the handle at the 



