TROUT-HATCHERIES 121 



torn board, stretching a piece of string dipped 

 in white lead along it, and then nailing on the 

 sides. Dovetailing is unnecessary and expen- 

 sive. 



The stands on which the troughs are set 

 should be of heavy lumber not easily moved, 

 and of the best quality, either white pine or 

 cypress, rejecting any lumber where knots com- 

 pletely penetrate the board, for it will leak. 



The floor of the hatching-house should be of 

 concrete, and a ditch be made the whole length 

 of the house, between the walk and lower end 

 of the third tier of troughs, to carry the water 

 into a sewer or a pipe conducting it to outside 

 ponds. There should also be a slope of about 

 an inch from the foundation wall on which the 

 supply-trough rests to the ditch, and there 

 should also be a slight concavity under each 

 set of troughs for drainage to the ditch. 



If the business is to be conducted on a huge scale, 

 and a vast number of eggs are to be sold, then, be- 

 sides the troughs described, it would be well to have 

 an egg-hatching trough of the Clark, Clark- William- 

 son, or some similar pattern. The United States 

 Bureau of Fisheries gives this description of the 



