PONDS. 



33 



The cross-bars also keep the eggs from being carried down by 

 the current. By using two small bevelled cog-wheels the front 

 roller can be turned by a handle. As the roller is turned for- 

 ward, the endless apron moves with it, and the eggs, as they come 

 to the edge of the roller, will fall off. The pan is placed in front 

 of the roller, and receives the eggs as they fall. The box need 

 not be more than two feet deep ; the depth depending upon the 

 size of the rollers, which in a short race may be quite small, and 

 the box not more than eighteen inches deep. The box is set 

 directly in the raceway, and intended to fill it completely. The 

 water may either enter with a fall over the top of the box, or the 

 top of the box may be cut down until the water will enter on the 

 level at which it is intended to stand over the screens. 



Fig. 2 is an enlarged view of the front of the same box. 



FIG. 2. 



A is a double row of coarse wire screens ; B apron of fine wire cloth ; 

 C pan to receive the eggs ; D screen ; E catch to hold screen D when raised. 



A screen, intended to prevent the fish from running beyond the 

 race or getting into the lower part of the box, may extend to the 

 bottom, or be arranged differently ; a screen placed at the front of 

 the box is also intended to prevent the fish from getting below. 

 When the eggs are to be taken, this screen is raised on hinges to an 



