52 



BULLETIN OF THE BUREAU OF FISHERIES. 



OB 



This camera was inclosed in a copper box (fig. 3). The top of the box was 

 open and was stiffened by a projecting rim against which a cover could be clamped 

 by means of eight metal screw-clamps. The joint between the rim of the box and 

 the cover was made water-tight by means of a heavy rubber gasket let into rectan- 

 gular grooves in both the rim and the cover. The box was intended to be used 

 at considerable depths. The pressure of the water on its outside would at 10 

 meters depth be one atmosphere plus the pressure exerted by a column of water 10 

 meters high, while the pressure on the inside of the box would be what it was when 

 the box was closed at the surface, one atmosphere. Under these circumstances 

 there was serious danger that the excess pressure on the outside of the box would 

 force the water through between the rim and the cover in spite of the most care- 

 ful construction of the joint between the 

 two. To overcome this difficulty, the cover 

 of the box was provided at its center with 

 an opening which extended upward into a 

 metal tube, and to this tube there was at- 

 tached an air-filled rubber bag of about 

 3 liters capacity. When the box was sub- 

 merged the pressure of the water on the 

 bag was communicated to the air within, 

 so that the pressure on the inner surface 

 of the box was exactly equal at all depths 

 to that on its outer surface. Thus there 

 was no excess pressure on the outer surface 

 of the box to force the water inward against 

 a less pressure within. 



The front of the box was provided with 

 three circular openings closed by plates 

 of glass with parallel surfaces. The one at 

 the center was opposite the lens; the two 

 above it were for the finder. A similar 

 opening on one side was also closed by 

 a glass plate and served for the finder. On the same side was a rod which 

 terminated at its outer end in a milled head. Its inner end extended, through a 

 stuffing box which was water-tight, to the interior of the box. By pulling the 

 rod in and out the shutter could be operated. A similar rod at the back of the box 

 could be slid in and out and served to change the plates. When in use the camera 

 was supported on a heavy tripod of iron. 



The apparatus was used either while the operator remained in shallow water 

 with his head and shoulders above the surface or when he had descended to the 

 bottom in a diver's suit. When working in shallow water, he put on the diver's 

 suit in order to be protected from the water, but omitted the casque covering the 

 head and the heavy weight ordinarily attached to the back and front of the suit. 

 Thus arrayed, he placed the tripod in position and attached the camera to it. In 



FIG. 3. Boutan's first apparatus. Box used in 1893 for 

 inclosing a detective camera to be used under water. 

 B, rubber balloon filled with air; D, handle at the 

 back for operating the magazine plate holder; O, open- 

 ing corresponding to the lens; OB, handle at the side 

 controlling the shutter; V, front finder; OV, lateral 

 finder. (Copy of fig. 1 in Boutan, 1893.) 



