384 



FISHING IN AMERICAN WATERS. 



fore nearly all husbanded after it passes through the boxes 

 by catching it in a marble trough and sending it back to the 

 supply reservoir by a pipe from a hydraulic ram, or a turbine 

 like that by which many reservoirs are supplied from rivers 

 or springs. These plans of aeration enable fish-culturists to 

 run the same water several times over the hatching-boxes; 

 but it is thought by some professors that for perfect safety 

 to the ova the water should be continually renewed, and not 

 flow over them a second time. 



In establishments of fish-culture like the government one 

 at Huningue, they endeavor to imitate nature more perfectly 

 than it can be done by a tier of boxes. They therefore build 

 a race-way thirty feet long, a yard wide, and eight inches 

 deep, as the trout-brook, and the fountain of equal tempera- 

 ture feeding it by pipes is the spring. In this race-way are 

 placed crosswise numerous trays of terra-cotta, glazed inside 

 to prevent contact of confervse with the ova, and in which, to 

 a frame of wood, glass tubes are fitted, and called a grit, the 

 French name for gridiron. The tray is six inches wide, four 

 inches deep, and as long as the race-way is wide. Both the 

 tray and the grille may be moved with ease to another race- 

 way, or the grille may be moved to clean the bottom of the 

 tray or for other purpose. The following cut may help illus- 

 trate. 



Fig. 1. Terra-cotta Tray, to fit crosswise in race-way. Fig. 2. Grille of glass tube*, 

 made to fit in the tray. Fig. 3. Race- way, as wide inside as the length of the tray. 



