52 BULLETIN OF THE BUREAU OF FISHERIES. 
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 serew-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 reetan- 
eular 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 difliculty, 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, 
» 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 
z my 
SS 
~ 
Fig. 8.— 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 of glass with parallel surfaces. The one at 
hk fronting nan plate Mller, 0D" the center was opposite the lens; the two 
controlling the shutter; V, front finder; OV, lateral above it were for the finder. A similar 
finder. (Copy of fig, Lin Boutan, 1898.) opening on one side was also closed by 
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 imner end extended, through a 
stulling 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 tron. 
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 
