Among the agencies which best perform this service of keeping the streams ever-flowing, are the forests and the works of the beaver. Rainfall accumulates in the brooks. The brooks conduct the water to the rivers. If across a river there be a beaver-dam, the pond formed by it will be a reservoir which will catch and retain some of the water coming into it during rainy days, and will thus delay the passage of all water which flows through it. Beaver-reservoirs are leaky ones, and if they are stored full during rainy days, the leaking helps to maintain the stream-flow in dry weather. A beaver-dam thus tends to distribute to the streams below it a moderate quantity of water each day. In other words, it spreads out or distributes the water of the few rainy days through all the days of the year. A river which flows steadily throughout the year is of inestimable value to mankind. If floods sweep a river, they do damage. If low water comes, the wheels of steamers and of manufactories cease to move, and damage or death may result. In maintaining a medium between the extremes of high and low water, the beaver's work is of profound importance. In helping beneficially to control a river, the beaver would render enormous service if allowed to construct his works at its source. During times of heavy rainfall, the water-flow carries with it, especially in unforested sections, great quantities of soil and sediment. Beaver-dams catch much of the material eroded from the hillsides above, and also prevent much erosion along the streams which they govern. They thus catch and deposit in place much valuable soil, the cream of the earth, that otherwise would be washed away and lost,--washed away into the rivers and harbors, impeding navigation and increasing river and harbor bills. There is an old Indian legend which says that after the Creator separated the land from the water he employed gigantic beavers to smooth it down and prepare it for the abode of man. This is appreciative and suggestive. Beaver-dams have had much to do with the shaping and creating of a great deal of the richest agricultural land in America. To-day there are many peaceful and productive valleys the soil of which has been accumulated and fixed in place by ages of engineering activities on the part of the beaver before the white man came. On both mountain and plain you may still see much of this good work accomplished by them. In the mountains, deep and almost useless gulches have been filled by beaver-dams with sediment, and in course of time changed to meadows. So far as I know, the upper course of every river in the Rockies is through a number of beaver-meadows, some of them acres in extent.