Trout Breeding. 123 



keep roots from the joints of drain tile. Having no ex- 

 perience with this, it is mentioned without comment. 



DAMS. 



These cannot be too carefully made to contend with 

 pressure, leakage, muskrats, crawfish, frost and other 

 things which are ever working to help water get to the 

 lowest possible point. The following is from a news- 

 paper which came after this chapter was begun : 



NuNDA, N. Y., Jan. 30, 1899. — Miller's dam went out 

 this morning. The washout, which resulted from un- 

 dermining by muskrats, entails heavy loss to mill own- 

 ers who have utilized the water. The disaster occurred 

 at a time when the valuable ice crop was nearly ready to 

 harvest. In building a dam, whether of earth, stone, 

 logs or a combination of any or all of these materials, 

 the greatest care must be taken to lay the foundation so 

 deep that no trickle of water excavation, of muskrat or 

 crawfish can go under it, and at the sides the dam should 

 extend so far as to prevent such mishaps. 



So much depends upon the nature of the ground and 

 the materials to be used that it is impossible to go fur- 

 ther into the construction of dams than to say : Make 

 them about twice as strong as you think they need be 

 and — then make them a little stronger. 



SCREENS FOR PONDS. 



Screens should be made at least ten times larger than 

 the space required for the water. For instance, if the 

 flow will pass through a hole six inches square, the 



