THE BEAVERS OF NORTH AMERICA 387 
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 
