74 ROMANCE OF THE BEAVER 



in the form of rising ground they are not daunted. 

 If the canal is needed it must be made, and the 

 work is carried on with the fullest appreciation of 

 the water problem, so far as it concerns them. The 

 little dams which separate the different levels are 

 simple affairs, mostly made of the material excavated. 

 Their length depends on the conditions. In flat 

 land none are built, for they are not needed. 

 Where the rise is very slight they are only the 

 width of the canal, increasing according to condi- 

 tions, so that in some places they are six or seven 

 times the width of the ditch. This presumably is 

 to prevent a sudden rush of water which might 

 cause injury to the entire system. The dams, 

 though quite simple, are strong enough to be used 

 as passage-ways ; the animals, swimming down the 

 canal, drag their burdens over the dams, which on 

 the upper side are but a few inches above the level 

 of the water. 



The width of these canals is usually about three 

 feet, with a depth of from one to three feet, seldom 

 deeper except when small pools are made evidently 

 with the idea of providing a hiding place in the 

 event of danger. Burrows are also made in the 

 banks probably for the same purpose. Apparently 

 every contingency is considered, and Httle or 

 nothing left to chance. The direction of the canals 

 must necessarily be variable. Wherever conditions 

 are favourable they are as straight as though laid 

 out by human engineers, but when there is any 



