I 



THE BEAVERS OF NORTH AMERICA 49 



cross-pieces would add to the strength of the dam, 

 and they would be easily dislodged by the pressure 

 of the flowing water. Whereas when placed with 

 butts upwards and headed against the current, the 

 points are forced against the bed of the river and 

 as weight is added to them they offer a barrier of 

 great strength, capable of resisting any ordinary 

 pressure of water. When the supply of water is 

 too limited, the beaver take the utmost care to see 

 that none is wasted, and the dam is coated with 

 unusual care to render it practically watertight 

 even towards the ends, and every tiny trickle is 

 stopped, sometimes by little dams only a few 

 inches long, just a handful or two of sod placed in 

 exactly the right position, perhaps some distance 

 from the actual structure. If during the autumn 

 these are trodden down or broken they will nearly 

 always be repaired within a few hours, so careful 

 is the supervision of the beaver. 



For some reason which can only be guessed at, 

 the beaver nearly always leave a roadway across 

 the dam leading from the pond to the outlet. This 

 is also much used by other animals of aquatic 

 habits such as mink, musquash and otter, and 

 though occasionally we also find a well-beaten 

 path running along the dam from bank to bank 

 this is not a beaver path. More often it is the 

 work of foxes, deer, lynx and other prowlers of 

 the woods, as well as man, who finds these 

 "bridges" most convenient. Many a time have 



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