It was stated above that the irrigation-canals and little channels were made above the level of the soil so that the water could at any point be tapped and allowed to flow over the surrounding land; and in a flat country like Babylonia it will be obvious that some means had to be employed for raising the water from its natural level to the higher level of the land. As we should expect, reference is made in the Babylonian inscriptions to irrigation-machines, and, although their exact form and construction are not described, they must have been very similar to those employed at the present day. The modern inhabitants of Mesopotamia employ four sorts of contrivances for raising the water into their irrigation-channels; three of these are quite primitive, and are those most commonly employed. The method which gives the least trouble and which is used wherever the conditions allow is a primitive form of water-wheel. This can be used only in a river with a good current. The wheel is formed of rough boughs and branches nailed together, with spokes joining the outer rims to a roughly hewn axle. A row of rough earthenware cups or bottles are tied round the outer rim for picking up the water, and a few rough paddles are fixed so that they stick out beyond the rim. The wheel is then fixed in place near the bank of the river, its axle resting in pillars of rough masonry. [Illustration: 293.jpg A MODERN MACHINE FOR IRRIGATION ON THE EUPHRATES.] As the current turns the wheel, the bottles on the rim dip below the surface and are raised up full. At the top of the wheel is fixed a trough made by hollowing half the trunk of a date-palm, and into this the bottles pour their water, which is conducted from the trough by means of a small aqueduct into the irrigation-channel on the bank. The convenience of the water-wheel will be obvious, for the water is raised without the labour of man or beast, and a constant supply is secured day and night so long as the current is strong enough to turn the wheel. The water can be cut off by blocking the wheel or tying it up. These wheels are most common on the Euphrates, and are usually set up where there is a slight drop in the river bed and the water runs swiftly over shallows. As the banks are very high, the wheels are necessarily huge contrivances in order to reach the level of the fields, and their very rough construction causes them to creak and groan as they turn with the current. In a convenient place in the river several of these are sometimes set up side by side, and the noise of their combined creakings can be heard from a great distance. Some idea of what one of these machines looks like can be obtained from the illustration. At Hit on the Euphrates a line of gigantic water-wheels is built across the river, and the noise they make is extraordinary.