58 BULLETIN OF THE BUREAU OF FISHERIES. 
light, and estimated that in good weather it would be possible to do this at depths 
of 7 or 8 meters. 
Although his flash-light apparatus proved to be unnecessary in shallow water 
and was subsequently abandoned as cumbersome and dangerous, it merits a 
word of description. His figure of it is reproduced in figure 8. In its final form it 
consisted of a cask of about 200 liters capacity closed at both ends, but with 
the lower end perforated by holes to permit the entrance of sea water. A bell jar 
of 5 or 6 liters capacity is held tightly against the upper end of the cask by means 
of the adjustable frame shown in the figure. The cavity of the jar communicates 
freely through many openings with that of the cask, and both are filled with, air. 
Within the bell jar is an alcohol lamp, and at the 
side of this is a metal reservoir (not shown in the 
figure), covered with asbestos and filled with mag- 
nesium powder. One end of a metal tube opens 
opposite the middle of the flame of the alcohol 
lamp (shown lighted in the figure) and communi- 
cates freely with the reservoir above. The other 
end of the tube extends into the cask, and is there 
connected to a rubber tube which extends through 
the side of the cask (at Cin fig. 8) and ends in 
a large rubber bulb. To use the apparatus, the 
reservoir is filled with magnesium powder and 
the alcohol lamp lighted, then the bell jar is 
fastened in place and the cask, heavily weighted 
at the bottom, is lowered into the water and set 
wherever needed. The air in the bell jar and cask 
is enough to keep the alcohol lamp burning for 
some time. To produce the flash it is merely 
necessary to press the bulb, when the magnesium 
powder, which has fallen from the reservoir into 
the tube, is blown against the flame from the end 
of the tube and ignited. This operation may be 
Fia. 8.—Boutan’s apparatus for using a mag- a 
nesium flash-light under water. The reser- repeated as long as the lamp remains burning and 
voir for the magnesium powder, the rubber . at 2 ' ins o o is 
Deib ane the welts uscaliceteadcanenes the reservoir contains magnesium. It is of course 
paratus arenot showninthefigure. (Copy mecessary to operate the shutter of the camera 
SNee ee aes sae simultaneously with the flash. 
Boutan (1900) describes and illustrates another illuminating apparatus which 
consists of two powerful are lamps inclosed in water-tight jackets of heavy metal, 
designed to withstand the pressure of the water at a depth of 50 meters or more. 
Each jacket was pierced by an opening into which was fitted a condensing lens, 
by which the emerging light was concentrated upon the object to be photographed. 
The two lamps were rigidly attached to the camera support and were supplied, 
through a cable, with current from storage batteries on board the boat. The 
same cable carried also an insulated wire through which an electro-magnet 
actuating the shutter of the camera could be controlled. The camera with lamps 
attached was lowered into the water. When the camera was on the bottom the 
lamp circuit was closed by means of a switch on board the boat, and when it was 
