50 BULLETIN OF THE BUREAU OF FISHERIES. 
be floated over the object to be photographed and a screen set up independently 
of it, or the screen may be attached to the glass itself. For the latter purpose a 
piece of half-inch band iron may be bent to form the three sides of a rectangle, 
8 by 12 inches, and this may be riveted as a bail (fig. 1, pl. rv) to the inside of the 
frame, about 8 inches from one side. The bail should turn on the rivets so that it, 
may be depressed into the frame when not in use. A screen may be formed by 
raising the bail and tying a piece of black cloth from it to the opposite side of the 
frame. In shallow, running water it is desirable to support the water glass from 
the bottom in order that it may not sink so much as to displace or distort the 
object to be photographed. It may be supported on four iron rods which run 
through metal sleeves soldered to the four corners of the frame. The rods may 
be fixed in any position in the sleeves by means of set screws, and may project 
upward far enough to support the upper edge of the screen. A water glass 
arranged in this way is shown in figure 2, plate rv, where it is being used for observa- 
tion, but with the same glass photographs were obtained of lamprey eels in the act of 
spawning. Such a photograph is reproduced in figure 2, plate m1, where the rough 
surface of the running water made the use of the water glass imperative. The 
white bands across the picture are the edges of the frame of the water glass. Outside 
this frame at the right, where the water is rough, little is visible. The screen was 
almost as necessary as the water glass. 
The writer has used water glasses of this type varying in size from 1 to 3 feet 
square. Those of 1 foot square are of use chiefly for observation, and even for 
this purpose the screen is a valuable addition. Those of 3 feet square are so 
unwieldy that a vehicle of some sort is needed to carry them. The size most suitable 
for field photography is 2 feet square, since this may be transported by hand. 
The method described in this section is suited only to shallow water, where 
the camera may be supported from a firm substratum. In deeper water the 
unsteadiness of the boat would interfere with the manipulation of a water glass or 
a screen. It might be possible, however, to construct a boat of which the water 
glass and the screen should form constituent parts. The method described permits 
only of views at angles of from about 48° to 90° to the water’s surface. Since it is 
not practicable to place the camera far above the water at these angles or to use 
screens of very large size, the pictures that may be taken are of near objects and 
the field covered by them is of limited extent. If a water glass is used, the camera 
must be near it and the field is limited by its frame. The method is, however, the 
only one known to the writer for certain kinds of work. Often, as in the case of 
the bass nest shown in figure 3, the objects to be photographed are in water so 
shallow that the camera must be placed above its surface; there is not room for it 
beneath. Often, though the object may be in deeper water, it is so surrounded 
by vegetation that it can not be seen from a little distance except from above. It 
must then be photographed from above. Where the water is both shallow and 
disturbed, as in small streams, the use of a water glass is essential. There are there- 
fore many objects about the borders of lakes and in streams to which this method 
may be applied when no other known method is available. On the other hand, 
wherever it is possible to use a submerged camera, results may be obtained with 
greater ease and certainty in the manner shown in the section which follows. 
