In many localities the canals or ditches dug and used by the beaver form their most necessary and extensive works. These canals require enormous labor and much skill. In point of interest they even excel the house and the dam. It is remarkable that of the thousands of stories concerning the beaver only a few have mentioned the beaver canals. These are labor-saving improvements, and not only enable the beaver to live easily and safely in places where he otherwise could not live at all, but apparently they allow him to live happily. The excavations made in taking material for house or dam commonly are turned to useful purpose. The beaver not only builds his mound-like house, but uses the basin thus formed in excavating earthy material for the house for a winter food depository. Ofttimes, too, in building the dam he does it by piling up the material dug from a ditch which runs parallel and close to the dam, and which is useful to him as a deep waterway after the dam is completed. In transporting trees for food-supply, water transportation is so much easier and safer than land, that wherever the immediate surroundings of the pond are comparatively level the beaver endeavors to lead water out to tree groves by digging a canal from the edge of the pond to these groves. The felled trees are by this means easily floated into the pond. One of the simplest forms of beaver canal is a narrow, outward extension of the pond. This varies in length from a few yards to one hundred feet or more. Another and fairly common form of canal is one that is built across low narrow necks of land which thrust out into large beaver ponds, or on narrow stretches of land around which crooked streams wander. The majority of beaver ponds are comparatively shallow over the greater portion of their area. In many cases it is not easy, or even possible, to deepen them. They may be so shallow that the pond freezes to the bottom in winter except in its small deeper portion. The shallow ponds are made more usable by a number of canals in the bottom. These canals assure deep-water stretches under all conditions. Most beaver ponds have a canal that closely parallels the dam. In some instances this is extended around the pond a few yards inside the shore-line. Two canals usually extend from the house. One of these connects with the canal by the dam, the other runs to the place on the shore (commonly at the end of a trail or slide) most visited by the beaver.