MIDDLETHIKD HATCHING-HOUSE. 



129 



The next move was to let the water fall freely into the end of 

 the hatching-box, and drop a perpendicular screen in front of 

 the top grille (Figs. 74, 75). This was all very well when the 

 eggs were incubating, but after the fry hatched, they amused 

 themselves by getting under this breakwater, and could not be 

 brought back for feeding. 



-/--- 20 



FIG. 76 scale - 



At last a simple board was tried, and found to work (Fig. 76). 

 The water spread over the board, which was placed at an angle, 

 and was thoroughly aerated. It was the cheapest, and there was 

 no mess, as the low edge of the breakwater touched the top end of 

 the hatching-box, and the water passed evenly through the fissure. 

 Sections of this breakwater and the safety-screen are given below 

 (Fig. 77). 



Fro. 77 scale ft. 



When the fry hatched, a safety-screen was fitted in the boxes, 

 and great trouble was found in making it tight, on account of 

 the ledge left for the support of the grilles. Now, with loose 

 fillets, which are removed, leaving a square corner, there is no 

 difficulty. 



The two hatching-boxes and the slate trays were arranged in 



