Sudan Anglo-Egyptian LOCUSTS ; IRRIGATION 117 > likely to be taken. The number of separate swarms is so large, however, and simultaneous reports are made from so many different districts of a province, that it is hard work to secure general destruction of the pest. Moreover, the local natives are slow in coming to the assistance of the locust officers.

Irrigation . - Almost the only water-lifting devices used by the natives are the ancient bullocksakia or Persianwheel, built entirely of wood, with an endless chain of earthen pots ; and the shaduf, with a long weighted lever worked by manual labour, and a goat skin , hauled up and down by donkey or mule . Iron sakias, which can be worked by a single animal and give a double output of water ,"have failed to become established, owing to lack of mechanical knowledge and suitable materials for repair. Iron bearings for the old wooden sakias , giving freer movement and there fore greater output, have fared little better, for the absence of the groaning noise made by the wooden bear ings prevented the owner at a distance from knowing whether the sakia was working or not. The amount of water that can be raised to any height by either the sakia or the shaduf is inconsiderable, and the area com manded is small. Irrigation by such means is restricted to a comparatively narrow strip ofland along the river bank , and the average native holding worked in this way extends to about ten acres only .

From the point of view of irrigation the Sudan mav he divided into four zones—the northern, the Gezira, the southern, and the Red Sea and Kassala zones . The first two are practically dependent upon artificial irri gation, the third relies upon rainfall , and the last depends upon natural inundations.

The northern zone comprises Khartum and the pro vinces north of it. Here artificial irrigation is carried on along the river hanks by means of two systems: either by canal irrigation , which necessitates thelifting of water from the river during the whole period of the growth of the crops , or by basin irrigation, by means of which certain blocks of land , having a surface level