The Arid Region is somewhat more than four-tenths of the total area of the United States, and as the agricultural interests of so great an area are dependent upon irrigation it will be interesting to consider certain questions relating to the economy and practicability of distributing the waters over the lands to be redeemed. ADVANTAGES OF IRRIGATION. There are two considerations that make irrigation attractive to the agriculturist. Crops thus cultivated are not subject to the vicissitudes of rainfall; the farmer fears no droughts; his labors are seldom interrupted and his crops rarely injured by storms. This immunity from drought and storm renders agricultural operations much more certain than in regions of greater humidity. Again, the water comes down from the mountains and plateaus freighted with fertilizing materials derived from the decaying vegetation and soils of the upper regions, which are spread by the flowing water over the cultivated lands. It is probable that the benefits derived from this source alone will be full compensation for the cost of the process. Hitherto these benefits have not been fully realized, from the fact that the methods employed have been more or less crude. When the flow of water over the land is too great or too rapid the fertilizing elements borne in the waters are carried past the fields, and a washing is produced which deprives the lands irrigated of their most valuable elements, and little streams cut the fields with channels injurious in diverse ways. Experience corrects these errors, and the irrigator soon learns to flood his lands gently, evenly, and economically. It may be anticipated that all the lands redeemed by irrigation in the Arid Region will be highly cultivated and abundantly productive, and agriculture will be but slightly subject to the vicissitudes of scant and excessive rainfall. A stranger entering this Arid Region is apt to conclude that the soils are sterile, because of their chemical composition, but experience demonstrates the fact that all the soils are suitable for agricultural purposes when properly supplied with water. It is true that some of the soils are overcharged with alkaline materials, but these can in time be “washed out”. Altogether the fact suggests that far too much attention has heretofore been paid to the chemical constitution of soils and too little to those physical conditions by which moisture and air are supplied to the roots of the growing plants. COÖPERATIVE LABOR OR CAPITAL NECESSARY FOR THE DEVELOPMENT OF IRRIGATION. Small streams can be taken out and distributed by individual enterprise, but coöperative labor or aggregated capital must be employed in taking out the larger streams.