In the arid West the extra-dry winds are insatiable. In many localities their annual capacity to absorb water is greater than the annual precipitation of water. In "dry-farming" localities, the central idea is to save all the water that Nature supplies, to prevent the moisture from evaporating, to protect it from the robber winds. Forests greatly check evaporation, and Professor L. G. Carpenter, the celebrated irrigation engineer, says that forests are absolutely necessary for the interests of irrigated agriculture. Considering the many influences of the forest that are beneficial to agriculture, it would seem as though ideal forest environments would be the best annual assurance that the crops of the field would not fail and that the soil would most generously respond to the seed-sower. So well is man served in the distribution of the waters and the management of their movements by the forests, that forests seem almost to think. The forest is an eternal mediator between winds and gravity in their never-ending struggle for the possession of the waters. The forest seems to try to take the intermittent and ever-varying rainfall and send the collected waters in slow and steady stream back to the sea. It has marked success, and one may say it is only to the extent the forest succeeds in doing this that the waters become helpful to man. Possibly they may need assistance in this work. Anyway, so great is the evaporation on the mountains of the West that John Muir says, "Cut down the groves and the streams will vanish." Many investigators assert that only thirty per cent of the rainfall is returned by the rivers to the sea. Evaporation--winds--probably carry away the greater portion of the remainder. Afforestation has created springs and streams, not by increasing rainfall, although the forests may do this, but by saving the water that falls,--by checking evaporation. On some exposed watersheds the winds carry off as much as ninety per cent of the annual precipitation. It seems plain that wider, better forests would mean deeper, steadier streams. Forests not only check evaporation, but they store water and guard it from the greed of gravity. The forest gets the water into the ground where a brake is put upon the pull of gravity. Forest floors are covered with fluffy little rugs and pierced with countless tree-roots. So all-absorbing is the porous, rug-covered forest floor that most of the water that falls in the forest goes into the ground; a small percentage may run off on the surface, but the greater part settles into the earth and seeps slowly by subterranean drainage, till at last it bubbles out in a spring some distance away and below the place where the raindrops came to earth. The underground drainage, upon which the forest insists, is much slower and steadier than the surface drainage of a treeless place. The tendency of the forest is to take the water of the widely separated rainy days and dole it out daily to the streams. The forest