GO 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, pi. iv) 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 hi 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 iv, 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 HI, 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 mariner shown in the section which follows. 



