TROUT CULTURE. 



755 



enters the trough that would clog the screen at the lower end 

 of the hatching trough and cause it to overflow and the fry to 

 escape. 



These hatching troughs are best made of soft wood, preferably 

 sound, clear white pine, and if possible have them up so that the 

 tops are three feet six inches above the floor, for convenience in 

 working over them. If the bottoms are an inch and a half thick, 

 three carpenter's horses will sustain them. A trough thirteen 

 feet long, fourteen inches and a quarter wide, and seven inches 

 deep, inside measure, will be sufficient for twenty-five thousand 

 trout fry after they are hatched and feeding, but will be capa- 

 ble of developing four times that number of eggs. The troughs 

 should be made of regular width, to a hair's breadth, in order 

 to have any hatching tray fit every trough in any part of it, and 

 the edges of the bottoms should be carefully dressed and the 



Lower Ends of Troughs with Outlet Pipes. 



sides nailed to them after being touched with thin white lead. 

 The ends should be let in (see cut), in order to be nailed both 

 ways and be tight. An inch-and-a-half hole in the bottom of the 

 lower end will take the waste water where required ; a sink outlet 

 with the cross-pieces cut out is good to attach a waste-pipe to ; 

 above this hole nail an upright strip to each side to hold the dam. 

 During the egg stage use one of two inches or less ; after hatching 



