In Mesopotamia, as in Egypt, there were waterways that could be used at any season for the transport of heavy masses. Quarries were made as near the banks of the Euphrates and Tigris as possible, and when a stone monster had to be carried to a town situated at some distance from both those rivers the canals by which the country was intersected in every direction supplied their place. Going down stream, and especially in flood time, no means of propulsion were required; the course of the boats or rafts was directed by means of heavy oars like those still used by the boatmen who navigate the Tigris in _keleks_, or rafts, supported on inflated hides; in ascending the streams towing was called into play, as we know from one of the Kouyundjik bas-reliefs.[412] In this the stone in course of transport is oblong in shape and is placed upon a wide flat boat, beyond which it extends both at the stern and the bows. It is securely fastened with pieces of wood held together by strong pins. There are three tow ropes, two fastened to the stone itself and the third to the bow of the boat. The towers pull upon these cables by means of smaller cords passed round the shoulders of each and spliced to the main ropes; by such means they could bring far more weight to bear than if they had been content to hold the cable in their hands, as in Egypt. The bas-relief in question is mutilated, but we may guess that a hundred men were attached to each cable, which would make three hundred in all obeying the single will of the superintending engineer who is perched upon the stone and directing their movements. On each flank of the gang march overseers armed with swords and rattans that would be quick to descend on the back and loins of any shirker. More than one instance of such punishment may be seen on the bas-relief reproduced in part in our Fig. 151. In its lower division two or three of these slave-drivers may be seen with their hands raised against the workmen; in one case the latter sinks to the ground beneath the blows rained upon him. The way in which the whole series of operations is represented in this Kouyundjik relief is most curious. High up in the field we often find the king himself, standing in his chariot and urging on the work. The whole occupies several of Layard's large plates. We can only reproduce the central group, which is the most interesting to the student of engineering in ancient Mesopotamia. [Illustration: FIG. 151.--The transport of a bull. Height of the slab, 7 feet 3 inches; British Museum.]