102 



Vermont agricultural report. 



Figure 6. Section of Hatching Trough, showing method of wedging a hatch- 

 ing tray and tail screen in place. 



Figure 7. Hatching Tray. Figures. Tail and Aerating Screens. 



For equipping a large hatchery it would be best to obtain for the 

 aeration screens a metal with coarser perforations than for the tail 

 screen, but in fitting up only a few troughs it will be cheaper to make 

 the two screens alike. To the one used as a tail screen, tack two 

 thicknesses of flannel or several thicknesses of cotton cloth on the 

 edge which comes in contact with the bottom of the trough. 

 This insures against escape of the alevins under the screen. If 

 you wedge the screen on the back side as shown in figure 6 at A, 

 A, pressing it firmly down at the same time, you will secure a 

 tight fit in the trough. 



The object of the aerating screen is to spread and aerate the 

 water and break its fall on to the fish in the trough. It also acts 

 as a cover for that portion of the trough where it is placed. 



Make the hatching trays, figure 7, 12*^ inches wide and 18 

 inches long, outside measure. Use for sides, pine, J-i inch by yi 

 inch and for ends, s/% inch by }i inch. Mortise together as shown 

 in figure 7. Cover with "galvanized wire cloth, 2x9 mesh, No. 

 24-23 double warp." This wire cloth is manufactured 24 inches 

 wide and can be halved to fit the trays. For a tray 12% by 18, 

 cut the cloth 12 by 17^. 



The wire cloth or perforated metals can be purchased of the 

 Clinton Wire Cloth Co., Clinton, Mass. Perforated metals are 

 also manufactured by the Harrington & King Perforating Co., 

 Chicago, 111. 



