PHOTOGRAPHY OF AQUATIC ANIMALS. 



55 



of screws against a rubber packing on the end of the box, so that the joint between 

 cover and box is made water tight. The rubber bag used in the first apparatus 

 seems to have been found unnecessary and is at any rate omitted. At the back 

 of the cover there projects a handle (M) by the manipulation of which the plates 

 may be changed. On the top at V is a sight by means of which the camera may 

 be directed at the desired object. Within the box at the back is a magazine plate 

 holder for six plates. This is represented at the left at C H in figure 9. It is so 

 arranged that when a plate has been exposed it may be made to fall forward by 

 turning the handle shown at M in the central figure. A second plate is at the 

 same time pushed into place by springs. When this has been exposed a second 

 turn of the handle allows the plate to fall and a third plate comes into place. Six 

 plates may thus be exposed without opening the box. On each side of the plate 

 holder are two cleats (gl) . These glide upon two rails on the inside of the box, one 

 on either side, so that 

 the plate holder may be 

 moved back and forth 

 on the rails away from 

 the lens or toward it. 

 By means of a set screw 

 the plate holder may be 

 firmly clamped at any 

 point on the rail. The 

 camera is focused by 

 means of this movement 

 of the plate holder. To 

 prevent reflection of 

 light from the lower 

 side of the surface film 

 of the water into the 

 camera there is pro- 

 vided a semicylindrical 

 shade shown at A B on the right in figure 5. It may be attached to the front of 

 the box above the lens by the arrangement shown at X. 



It is not possible to focus after the box has been closed in order to immerse it. 

 Consequently one of the rails upon which the plate holder moves must be provided 

 with a scale. The divisions on this scale correspond to different distances between 

 the lens and the object to be photographed. When the plate holder is set at a 

 certain division of the scale the camera is in focus for objects at a distance of 4 

 meters; when set at another division for objects at 2 meters. It is therefore 

 necessary to determine before the camera box is closed at what distance the object 

 is to be photographed and to focus by setting the plate holder at the corresponding 

 division on the scale. While the box is immersed this focus cannot be changed. 

 The divisions to be marked on this scale were ob tamed by focusing on submerged 

 objects while the front of the camera was also submerged. This necessitated the 

 use of special devices, which need not be described here. 



FIG. 5. Boutan's third apparatus (1893). A, metal camera box; M, handle control- 

 ling the changing of plates; MO, handle controlling the shutter; O, opening for 

 the lens; P, feet for supporting the apparatus; V, sight; X, points of attachment 

 of the hood AB; CII, magazine holder for six plates; gl, cleats by means of 

 which the holder glides on a rail inside the box; p/, plates; /, pin which holds the 

 front plate in place. (Copy of fig. 3 in Boutan, 1898.) 



