THE BEAVERS OF NORTH AMERICA 37 



and though at first glance we might sometimes be 

 led to imagine that improvement could be made in 

 the method, if we go far enough into the question 

 and thoroughly appreciate the animal's point of 

 view, his needs and the natural restrictions of his 

 ability, we are nearly always forced to acknowledge 

 the success of his methods. Certainly in the 

 building of the dams, improvement both in the 

 choice of site and the actual execution of the work 

 is most difficult to suggest. Indeed it is very 

 doubtful whether the average man could, without 

 tools, or even with the help of an axe, overcome 

 the obstacles which are encountered by the beaver. 

 Most writers in dealing with the subject are 

 inclined to pay too much importance to the curve 

 of a dam. Some assume that all dams are built 

 with the curve against the current, others that such 

 is the case only when the flow of water is swift, 

 while some claim that the curve is most often down 

 stream. I have seen a great many dams built in 

 many different situations and under very different 

 conditions, and the conclusion which has been 

 forced on me is that there is no rule to govern the 

 curve. It just happens. I have seen quite large 

 dams, two or three hundred feet long, which were 

 almost straight, others had a decided curve up 

 stream. Others again, under apparently similar 

 conditions, were curved with the current, while on 

 more than one occasion the dam has been like a 

 drawn-out letter S, that is to say with half of it 



