THE BEAVERS 1273 



such dams and pools may be seen one above another in the course of the stream. 

 It is believed that the original object of tree-felling is to obtain a supply of food for 

 winter, and that the employment of the peeled trunks and branches for the construc- 

 tion of the dam and lodges is a secondary development. The beaver fells the trees 

 it requires by gnawing through their stems with its sharp front teeth at a short dis- 

 tance above the ground, the stem being generally gnawed nearly equally all round, 

 till the tree falls of its own weight. As trees on a river bank generally incline 

 toward the water, they usually fall in the required direction. Sometimes, however, 

 the animals miscalculate, and trees which they have felled may be seen caught in 

 the forks of neighboring stems. The trees selected for felling are usually from five 

 to eight or nine inches in diameter, but occasionally trunks of as much as eighteen 

 across are successfully attacked. The beaver goes to work in a thoroughly scien- 

 tific manner, gnawing out very large chips, which are sometimes as much as nine 

 inches in length. When the trees are felled, they are stripped of their boughs, and 

 the trunks cut into lengths of five or six feet, which, after being barked, are rolled 

 into the stream or pond, and employed in the construction of the dam and lodges. 



The term " lodge," it "may be explained, is applied in America to the abodes 

 constructed by these animals in the water of their ponds. It is now generally ac- 

 cepted that the lodge is nothing more than an extreme development of the burrows 

 or " wash " in the banks. On this subject Mr. Martin writes as follows: "Start- 

 ing with the simple burrow, the next step is the accumulation of logs and branches 

 about its entrance, forming what is called a 'bank-lodge.' In places where the 

 water is shallow toward the shore, a great advantage would be derived from extend- 

 ing this artificial covering of brushwood, so that in time a natural evolution of the 

 lodge disconnected entirely from the shore would take place, and form an independ- 

 ent and very convenient refuge from landward enemies." The lodge contains a 

 large internal chamber, lined with grass, and is entered by several approaches 

 beneath the surface of the water. The construction of the lodge is, however, of a 

 much less elaborate nature than has often been stated to be the case. On this point 

 Mr. Martin writes that ' ' the beaver-lodge is generally included in the list of marvels 

 reserved for the investigation of those who visit beaver districts, and yet no greater 

 disappointment awaits the inquirer than the first inspection of one. Somehow the 

 minds of all lovers of natural history become affected by the fabulous accounts con- 

 cerning this structure, and it is a shock to stand for the first time before a pile of 

 twigs, branches, and logs, heaped in disorder upon a small dome of mud, and to 

 learn that this constitutes the famous lodge. Of course the superficial glance does 

 not convey all that can be learned in connection with this work, but it does most 

 completely disillusionize the mind. On breaking through the upper walls, the 

 interior is found to be similar to the general type of an animal's sleeping apartment, 

 and has scarcely any distinguishing characteristic." 



Both dams and lodges are made more or less impervious to water by the 

 addition of a quantity of mud, which is plastered on by the beavers with the aid of 

 the fore- feet, and not, as is often supposed, with the assistance of the tail; the latter 

 organ acting only as a rudder in swimming. The length of a beaver dam may 

 occasionally be as much as one hundred and fifty or two hundred yards, and their 



