110 THE AMERICAN BEAVER. 



ing, about six feet wide, where the lower face was 

 constructed of interlaced sticks, while the water face 

 was banked in with earth. In the engraving, which 

 was made from a drawing, the hedge is removed for 

 the purpose of showing the embankment. The fall of 

 water which passed over the crest of the dam at the 

 opening, was about a foot and a half I was first 

 drawn to the place by the sound of the falling water 

 while passing by on the trail at some distance. 



This dam realizes the earliest current descriptions 

 of these works by Buflfon and other writers, particu- 

 larly its opening for the surplus water, and the hedge 

 growing upon its summit. In the Lake Superior re- 

 gion, and upon the head waters of the Yellowstone 

 and the Missouri, they are comparatively rare. All 

 the large dams are of the other kind. In some in- 

 stances both forms are found in the same dam, as will 

 hereafter be shown. 



It was another conspicuous feature of beaver dams, 

 according to the early descriptions, that the trunk of 

 a tree, cut down for the purpose, often served as the 

 foundation of the structure. After selecting a proper 

 site, their first act, as a general rule, was said to be 

 the felling of a tree across the channel upon which 

 the work was to be constructed. There is one dam, 

 and but one, within the area of the map (No. 9), 

 which has incorporated within it the trunk of a fallen 

 tree. Except for this circumstance it would not de- 

 serve a special notice. 



The tree in question (Plate XI.), which was a pine, 

 three and a half feet in diameter, had Mien from its 

 own decay. For aught that appeared, it might have 

 fallen upon a dam previously constructed, and become 



