Engineering Wonders of the World
Volume I

84 ENGINEERING WONDERS OF THE WORLD. APACHE INDIANS AT WORK ON ROAD-MAKING IN ARIZONA. APPLES GROWN ON ONCE DESERT LAND. system is the most perfect in the world. Of recent years rice cultivation in this section of the United States has been greatly retarded, and many large plantations have been aban- doned, owing to the erratic flow of the streams. Since the denudation of the forest-covered slopes at th© headwaters, rivers formerly regular in discharge and readily controlled have now become raging torrents. Floods now rise in a single night, and no dikes can withstand their force. The cost of irrigating and harvesting rice along the coast is heavier than in other sec- tions not dependent upon the action of the tides. The work of cultivating and harvest- ing is also great, and as the ground is moist it is necessary to gather the rice by hand and carry it to higher ground to be threshed and cleaned. The plantations along the lower Mississippi River have a front levee 40 feet thick at the base and 8 feet high. From February 1 to J uly 1 the water rises from two to four feet above the surface of r Natui^al the rice land, affording natural ^rr^at*on* irrigation. During other periods the water is conveyed to the fields by several methods. The most common is to use a flume constructed on much the same principles as those of the trunk employed in the Carolinas. Siphons also are used. Considerable areas are supplied by pumping plants, drawing the water from the rivers ; and many plantations are irrigated by a system of tile flues set below the surface. By stopping these at the lower end the water is forced up through a layer of earth as needed. When the plugs are withdrawn the water passes off through the tiles. DATE PALMS ON IRRIGATED LAND.