96 ROMANCE OF THE BEAVER 
or supporting dams had to be considered. Who 
could tell but that the main structures might at 
any moment give way under the pressure of water, 
or the still greater pressure of broken ice, that 
enemy to all dams in the northern countries, 
whether built by man or beaver? Strong indeed 
must be the structure that will withstand its 
onslaught, when borne by the spring floods it 
hurls itself at every obstacle. Well-built bridges 
are smashed like matchwood, great trees are 
uprooted, banks are torn down, and ponderous 
boulders are swept before it, as creaking and 
groaning it grinds and forces its impetuous way 
in the company of the raging streams. The 
beaver, knowing the possibility of such an on- 
slaught against their dams, whether by experience, 
instinct or reason, finally decided to erect smaller 
dams below the main structures. Owing to the 
narrowing of the gully it was only necessary that 
these dams should be very short, one near the 
larger outlet being twenty-five feet long the other 
fifteen, but as the ground sloped suddenly they 
had to be fairly high in proportion to their length. 
The work was carried on regularly and without 
difficulty, as there was very little water passing 
down the stream and building material was every- 
where abundant. 
Autumn stole upon the beavers while they were 
engaged on their many tasks. The days shortened, 
so that the increasing length of the nights gave 
