below, a
dam one-fourth the length might have given them better water. This
must be said, however, for the builders, that perhaps they found a
better soil for digging their tunnels, or a more convenient spot for
their houses near their own dam; or that they knew what they wanted
better than their critic did. I think undoubtedly the young beavers
often make mistakes, but I think also, from studying a good many dams,
that they profit by disaster, and build better; and that on the whole
their mistakes are not proportionally greater than those of human
builders.

Sometimes a dam proves a very white elephant on their hands. The site
is not well chosen, or the stream difficult, and the restrained water
pours round the ends of their dam, cutting them away. They build the
dam longer at once; but again the water pours round on its work of
destruction. So they keep on building, an interminable structure, till
the frosts come, and they must cut their wood and tumble their houses
together in a desperate hurry to be ready when the ice closes over
them.

But on alder streams, where the current is sluggish and the soil soft,
one sometimes finds a wonderfully ingenious device for remedying the
above difficulty. When the dam is built, and the water deep enough for
safety, the beavers dig a canal around one end of the dam to carry off
the surplus water. I know of nothing in all the woods and fields that
brings one closer in thought and sympathy to the little wild folk than
to come across one of these canals, the water pouring safely through
it past the beaver's handiwork, the dam stretching straight and solid
across the stream, and the domed houses rising beyond.

Once I found where the beavers had utilized man's work. A huge log dam
had been built on a wilderness stream to secure a head of water for
driving logs from the lumber woods. When the pines and fourteen-inch
spruce were all gone, the works were abandoned, and the dam left--with
the gates open, of course. A pair of young beavers, prospecting for a
winter home, found the place and were suited exactly. They rolled a
sunken log across the gates for a foundation, filled them up with
alder bushes and stones, and the work was done. When I found the
place they had a pond a mile wide to play in. Their house was in a
beautiful spot, under a big hemlock; and their doorway slanted off
into twenty feet of water. That site was certainly well chosen.

Another dam that I found one winter