TROUT-HATCHERIES 123 



end of which contains the slot fitting snugly against 

 the upper end of the compartment in which is fitted 

 a tin over-flow. The whole is held in place by a 

 cross-bar or binder, which fits in grooves cut in both 

 sides of the tank. The binder, which rests upon the 

 box, keeps it from rising in the water, and is provided 

 with feet so placed as to prevent the trays from float- 

 ing in the box itself. Each tray is capable of holdii^ 

 5,000 brook-trout eggs, the ninth or top tray being 

 used only as a cover. There are several other types 

 of purely egg-hatching troughs or boxes, the general 

 principle of all being a series of dams, the water flow- 

 ing alternately over and under. These troughs, how- 

 ever, are for hatching or eyeing eggs only, and are 

 not suitable for carrying fry or advanced fry. 



Suggestions. — ^If the water-supply is from a 

 deep spring, there will be no need for a stove 

 or heating apparatus in the hatching-house, ex- 

 cept to permit the men to warm their hands 

 after having them in the cold water for some 

 time, as the spring water, averaging say from 

 45 to 50 degrees of warmth, will keep the house 

 fairly comfortable. If the water is creek water 

 then it may be necessary to have a heating ap- 

 paratus to give some warmth to the building; 



