58 DOMESTICATED TROUT. 



or eight inches. This second lower tier of boxes is, 

 however, somewhat objectionable, because whenever 

 the screens of the upper boxes are cleaned, or the 

 water in them for any reason disturbed, the lower ones, 

 in taking the washings from the u])per, must suffer. 

 This can be obviated, it is true, by cutting off the water 

 temporarily, but this, again, is not only dangerous, but 

 often inconvenient. It is hest, therefore, not to use the 

 water but once in hatching, if you have enough. Still it 

 can be used twice, if necessary, without great injury. 

 If you have plenty of water, I would recommend shorter 

 troughs and more of them. There is no harm in hav- 

 ing them twelve inches wide. I prefer ten or eight 

 inches, however. They should be at least six inches 

 in height in the inside, to guard against their running 

 over, from the screens clogging up, and it is desirable 

 to have them still higher, say eight inches, if you 

 mean to keep the young fry in them any considerable 

 time after they hatch. The troughs should be divided 

 into compartments about one inch deep and fifteen 

 inches long, by nailing charred cleats of the required 

 depth transversely on the bottom of the trough, at 

 regular intervals of fifteen inches. The head of the 

 trough should be placed just under the distribut- 

 ing spout, from which there should be a fall of a 

 few inches ; the trough should be high enough from the 

 floor, if practicable, to be examined by a person stand- 

 ing. The troughs should be inclined, so that the water 

 will make a gentle ripple over the cleats. A grade 

 havinor ^ fall of one and one fourth inches to ten feet 

 will do very well, but be sure to have enough slope to 



