The delta of the Colorado River, in Arizona and California, is often described as America’s Valley of the Nile. In climate, soil and agricultural conditions it is singularly like the great valley of Egypt. The conquest of this turbulent river of the West was a splendid achievement. The engineering features of the Yuma project, in Arizona and California, are in many respects original. The control of the stream called for a long diversion dam and more than 100 miles of strong levees. The dam is nearly a mile long, nineteen feet high, and 267 feet wide on the bottom. Its type is similar to that of the barrages of the English engineers in India. Laid on a foundation of shifting sand and silt, it is held in place by its enormous weight, 600,000 tons. Owing to the quantities of silt carried by this stream, the dam is provided with a large settling basin, sluiceway and gates, by which comparatively clear water is turned into the canals. The main canal system extends for twelve miles on the California side. Just opposite the city of Yuma, Arizona, the entire volume, 1,000 cubic feet per second, is dropped in a siphon 1,000 feet long and carried under the river to the Arizona side. Here are 90,000 acres of valley and mesa land, and more than half of the area is being developed intensively. The soil is of great depth and extremely fertile, and the climate is adapted to the growing of a wide variety of crops. The mesa lands which are to be opened later are described as frostless, and especially adapted to growing citrus and other semi-tropic crops. _The Pathfinder Dam_ [Illustration: GRAND RIVER, ROLLER-TOP DIVISION DAM, COLORADO Electrically operated rollers are lifted to pass the floods] Far from the beaten path of man, fifty miles from the nearest railway in a deep and narrow granite canyon of the North Platte River, in southern Wyoming, engineers in 1903 located an admirable site for a high masonry dam. Early maps of the expedition of Gen. John C. Frémont, the explorer, indicated the spot as the scene of a disaster where these adventurers suffered the wreck of their boats and the loss of many belongings in the rapids of the river. Hence the name Pathfinder dam. This is a beautiful structure of huge granite blocks 225 feet high and 600 feet long on top, and its cost was $1,000,000. [Illustration: SHOSHONE RESERVOIR, WYOMING] Judged from the service it has rendered mankind already, as a preventive against disastrous floods and a guarantor of generous harvests, it deserves a high place among the storage structures of the world. Since its completion the North Platte River has been completely tamed, and angry floods that once wrought millions of dollars of destruction are now so distributed as to insure an annual harvest valued at $6,000,000 in a region once occupied only by nomadic herdsmen. _Transferring a River_