Page:The American Cyclopædia (1879) Volume IX.djvu/429

 IRRIGATION 415 ly for navigation ; and their ruins are among the interesting antiquities of those countries. Into some of these canals the water was raised by machines which consisted of rude buckets worked by oxen, in much the same manner still practised on the hanks of the Tigris and Euphrates. Among the ancient Egyptians ir- rigation was performed with water flowing di- rectly from the Nile, or raised out of it, or, as was often the case, from wells. The most an- cient machine was the sweep, or bucket sus- pended from a balanced pole, such as was gen- erally used many years ago in this country, and is still in some parts at the present time. Af- terward the chain of pots, or sakiyeh, was used, as it also was by the Assyrians and Babylonians. At present water is raised from the Nile by means of Persian wheels, which differ from the chain of pots by the vessels being hung upon the periphery of a large wheel, and so adjusted as to tip over and empty their con- tents into a trough when they arrive at a cer- tain height, instead of being placed upon an endless chain or rope. In the agriculture of Italy, France, and Spain great attention is paid to irrigation. The Romans during several cen- turies constructed extensive works, which are still in use. The water is carried not only over the grass lands and the rice fields, but between the ridges in the grain fields and through the vineyards round the roots of the vines. The distribution of it is controlled by a regular sys- tem. The state itself claims the waters of all the rivers of Lombardy ; and in the Venetian territories all the springs and collections of rain water belong to the government. The use of the waters of the rivers is rented out at a cer- tain price by the hour or half hour, or for so many days at certain seasons of the year. Persons are entitled to make canals through the lands of others lying between them and the river, on paying for the damage thus caused. The channels for leading the water into the lands and the parallel channels alternating with them, placed at about 6 in. lower elevation for conveying the water away, are laid out with great regularity, at distances usually of about 22 ft. between them. In summer the water is allowed to flow through them for several hours about once a week, but the flow is steadily kept up from October to April, except at the time of cutting the grass. In northern Italy lands that can be irrigated rent for one third more than the same class of lands not thus im- proved. On the American continent, the an- cient inhabitants of Peru were found by their 'Spanish conquerors in the use of the most costly works constructed for irrigating their lands. Prescott says : " Canals and aqueducts were seen crossing the low lands in all direc- tions, and spreading over the country like a vast network, diffusing fertility and beauty around them." In the article AQUEDUCT the wonderful magnitude of some of these works has been noticed. The Aztecs of Mexico also made use of similar means to counteract the 440 VOL. ix. 27 natural dryness of their atmosphere ; and in the beautiful gardens of Iztapalapan, watered by canals and aqueducts, and moistened by the spray of fountains, was exhibited to the as- tonished Spaniards a perfection of horticulture at that time unknown in their own country. Irrigation on a large scale and by the Italian method was attempted in England in the 16th century, on the estate of Babraham in Cam- bridgeshire ; but the system was not fairly es- tablished as an important branch of agriculture until the commencement of the present cen- tury. Of late years what are called water meadows have become a common feature in some of the best cultivated counties, especially in Wilts, Devon, Somerset, and Gloucester, and also in the southern part of Scotland. Some peculiar methods have been introduced, as that of irrigating with currents of liquid ma- nure; and the sewerage of Edinburgh is dis- tributed on the same principle with the most beneficial results over the meadows that lie be- low the level of the city. The grass grown upon the meadows thus watered has to be cut about once a month from April to November, and it is described as remarkably tender and succulent, admirably adapted as a milk-pro- ducing food for cows. With some exceptions the general practice is not to leave the water standing upon the lands ; but taking it from a running stream (which should be tapped if practicable far enough above the meadow for the water to flow in from the bottom of the current, where it is most charged with sedi- ment), it is conveyed in a main channel around the further margin of the meadow, and numer- ous side branches lead off in nearly parallel lines into its central portions, each tapering to a point. These are commonly interlocked by others proceeding in the opposite direction from the main channel, on the lower side of its cir- cuit, as it passes hack to the river. The second set, being at a lower level than the first, serve as drains, conveying the water that overflows from the first to the main channel, which in the latter part of its course is no longer a feed- er but a drain. The water is allowed to flow through this system as often as may be desira- ble, care being taken that it shall not lie at rest at any time, the effect of which is found to be a tendency to cause the growth of a coarse grass. This method is called bed-work irriga- tion, from the ground being laid out in nearly regular beds by the channels. It is applica- ble only to tolerably level land. By another method, called catch work, irrigation is conve- niently applied to uneven ground. One set of channels follow the contour lines of the ground, each retaining its own level. These are crossed nearly at right angles by numerous other small channels, which are fed at their upper elids by the main gutter, and the water is directed by stops of clods of earth into the level side chan- nels, which are filled as may be desired. The laying out of the work and management of the operation, so as to distribute the water uniform-