24: FILTER. 



Sediment destroys the eggs by suffocating them. Gravel 

 is put into the troughs in order to support the eggs at the 

 fewest possible points, and let the water touch as much of 

 the surface of the egg as possible. Sediment falling on the 

 egg keeps the water off and destroys its life as effectually 

 as being buried in the ground would destroy a man's life. 

 If sediment falls upon the eggs it may, be removed by 

 gently agitating the eggs with a feather, or better still, 

 by creating a current in the water with a feather, which 

 current the eggs will follow, and as they roll over, the sed- 

 iment will drop off. But the Trout breeder has no business 

 to be troubled in this way. If his apparatus is constructed 

 right, and his filter properly attended to, there will not be 

 sediment enough in the troughs to hurt the eggs, from the 

 time they are put in until the fish are hatched out. The 

 pipe which is let into the spring should have wire netting 

 around it where the water comes in, to keep out impuri- 

 ties. This netting should be spread out so as to give a 

 greater surface than the mouth of the pipe. If the net- 

 ting covers only the mouth of the pipe, every speck of dirt 

 which lodges on the netting diminishes by so mucli the 

 supply of water ; but if the surface of the netting is in- 

 creased, much of it may be stopped up with dust without 

 lessening the supply of water. The best way is to take a 

 board, say one foot square for each inch of diameter of the 

 pipe, and run the pipe through a hole in the middle of the 

 board, fitting it well ; then nail netting on the edges ol 

 the board, so as to bulge it out in a half globe form. Thi& 

 should be looked after occasionally, but if the spring is 

 closely walled up, and the netting placed beneath the sur- 

 face of the water, it will not probably need cleaning 

 through the season. 



Gkavel for Troughs. — The gravel for the troughs 

 should be quite fine — about the size of peas. It is better 



