PHOYOGRAPHY OF AQUATIC ANIMALS. 49 
distant objects which would otherwise be reflected into the camera from the surface 
of the water are cut off. If the sunlight is permitted to fall on that face of the 
screen which is toward the camera, it is reflected from the screen to the surface of 
the water and thenge into the camera. _A picture taken under these conditions 
may show, besides the object under the water, also the screen itself, although this 
image of the screen is usually so faint that it does not interfere with the use of the 
picture for scientific purposes. 
When the screen has been properly set the operator has merely to adjust the 
camera and make the exposure in the customary way. If the subjects are fish they 
will usually have been frightened away, but if the fish are engaged in nest building 
or in some other occupation that attracts them to a particular spot, they will, in 
most cases, return after a time varying from five minutes to anhour. The operator 
has merely to remain quiet until this happens. The photographer may focus his 
camera on the spot to which the fish is likely to return and then withdraw and 
operate the camera from a distance by pulling a string or pressing a bulb when 
the fish returns. The method is of most use in securing photographs of the nests 
and habitats of fish in shallow water, yet the writer has succeeded by means of it 
in making some satisfactory photographs of fish on the nest. 
The result of using the screen is shown in figure 1 of plate m1, which is a photo- 
graph of the nest of a small-mouthed black bass. The screen in this case was stretched 
on aframe and was held by hand. Within the limits of the reflection of the screen 
in the water’s surface the bottom may be seen clearly. At the center are the larger 
stones which form the bottom of the nest, and these show sharply the details of 
their markings. Outside the limits of the reflection of the screen the bottom is not 
clearly visible; its image has been obscured on the sensitive plate by the bright 
light reflected from the surface of the water. The sun struck the back of the screen 
from the left, as is shown by the shadow which lies close to the screen. Within 
the limits of this shadow the plate was underexposed and details of the bottom 
are not visible. With a longer exposure as good a negative could have been made 
of what lay in the shadow. 
If the surface of the water is not smooth it may be made so by a water glass, 
which may be constructed as follows (fig. 1, pl. rv): A square frame is made of 
heavy galvanized iron, and measures 3} inches deep and 12 inches on each side 
within. One of its edges (the top) is turned outward three-fourths of an inch and 
then downward one-half inch to form a lip. This stiffens the frame and tends to pre- 
vent water from slopping into it. The lower edge of the frame is turned outward 
about half an inch to forma flat surface, against which the glass, 13 inches square, is 
bedded in aquarium cement. After the glass is in position four trough-shaped pieces 
are soldered to the sides of the frame and to one another in the manner shown in the 
figure. The free edges of these pieces project inward beneath the lower surface of 
the glass and support it. Before the pieces are soldered into place cement is placed 
between them and the lower face of the glass. The whole border of the glass is thus 
bedded in cement on both surfaces and at the edge. To protect the glass when not in 
use a flat cover is provided, which fits against its lower face. Such a water glass may 
