OUR FOUR-FOOTED NEIGHBORS. 319 



when the trappers have made holes in them. There are 

 sometimes several dams on the same stream, one below an- 

 other, so that the water of each flows back nearly to the 

 foot of that above. Sometimes they seem to protect a 

 large dam by a smaller one below, so that the pressure of 

 the water from below may resist the pressure at the bottom 

 of the principal dam. In one case seven dams were found 

 on the same stream within a distance of one hundred and 

 sixty feet. 



7. But I do not think that even the dams made by 

 beavers show so much thought or ingenuity as their canals. 

 It is much easier and safer for them to carry their food 

 and building material by water than by land. So some-, 

 times they cut a canal across the bend of a stream to 

 shorten the distance. Sometimes, again, it is cut through 

 the mud until they reach firm ground for their burrows. 

 These canals are usually about three feet wide and three 

 deep, and they are sometimes five hundred feet long. Any 

 engineer will tell you that it needs a good deal of skill and 

 ingenuity to decide where to lay out such a canal as that, 

 and then to cut it regularly, so that the water shall flow 

 smoothly through. And the most remarkable thing of all 

 is, that they know how to combine the principles of the 

 canal and the dam, so that when they co'me to an obstruc- 

 tion, such as a rock in the bed of their stream, they imme- 

 diately make a dam to secure the necessary flow of water. 

 Successive generations evidently work for many years upon 

 these canals, and I can hardly think of anything else done 

 by an animal that shows so much contrivance. 



8. The house or lodge is always separate from the dam, 

 and it looks like that of the musquash, only that it is much 

 larger, and built of stronger materials. Sometimes a cord 

 of wood is used in building one house. There is an en- 

 trance under water like that of the musquash, and some- 

 times two. These openings are very neatly made. The 



