46 DOMESTICATED TROUT. 



the house comparatively warm. There is often a differ- 

 ence of 30° between the outside air and the interior 

 of the hatching room in extremely cold weather. 



It is a good plan to build the walls thick, and then 

 the water running through will keep the air not very 

 many degrees from its own temperature. 



This makes a much more comfortable room to 

 work in. 



The shape of the hatching house will be determined 

 almost wholly by local considerations. 



It is becoming quite the custom now to admit the 

 light into the hatching room by large movable sky- 

 lights in the roof; this is optional, however, unless 

 sufficient light cannot be obtained otherwise. 



I will only add that if the four rooms mentioned — 

 the office, storeroom, meat-room, and hatching room — 

 are included in one building, the first three should be 

 separated from the hatching room by a partition pre- 

 pared with waterproof cement, or other covering, 

 impervious to water. 



