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.
The block of alabaster that we saw a moment ago on a boat towed by hundreds of human arms has been delivered to the sculptors and has put on, under their hands, the rough form of a mitred, human-headed bull. It will be completed after being put in place; the last touches of the chisel and the brush will then be given to it; but the heaviest part of the work is already done and the block has lost much of its original size and weight. Firmly packed with timber, the bull lies upon its side upon a sledge which is curved in front like a boat, or a modern sleigh. Two cables are fastened to its prow and two to its stern. The engineer is again seated upon the stone and claps his hands to give the time, but now he is accompanied by three soldiers who appear to support his authority by voice and gesture. In order to prevent friction and to facilitate the movement of the sledge, rollers are thrust beneath its runners as they progress. Before the huge mass will start, however, the straining cords and muscles have to be helped by a thrust from behind. This is given by means of a huge lever, upon which a number of men pull with all their weight, while its curved foot is engaged under the sledge. A workman is occupied with the reinforcement of the fulcrum by thrusting a wedge in between its upper surface and the lower edge of the lever. When everything is ready a signal will be given, the men behind will throw their weight upon the lever, the sledge will rise a little, the ropes will strain and tighten, and the heavy mass will glide forward upon the greased rollers until arms and legs give out and an interval for rest is called, to be followed presently by a repetition of the same process. Every precaution is taken to minimize the effect of any accident that may take place in the course of the operation. Behind the sledge spare ropes and levers are carried, some upon men's backs, others on small handcarts. There are also a number of workmen carrying rollers.
We shall only refer to one more of these reliefs and that the one with which the series appears to close ([Fig. 152]). This carved picture has been thought, not without reason, to represent the erection of the bull[413] in its destined place. After its slow but uninterrupted march the huge monster has arrived upon the plateau where it has been awaited. By one great final effort it has been dragged up an inclined plane to the summit of the mound and has been set upon its feet. Nothing remains to be done but to pull and thrust it into its place against the doorway it has to guard and ornament. The same sledge, the same rollers, the same lever, the same precautions against accident are to be recognized here as in the last picture. The only difference is in the position of the statue itself. Standing upright like this it is much more liable to injury than when prone on its flank. New safeguards have therefore been introduced. It is packed under its belly with squares of wood and inclosed in scaffolding to prevent dangerous vibration. Additional precautions against this latter danger are provided by gangs of men who walk at each side and hold, some ropes fastened to the uprights of the scaffolding, others long forked poles engaged under its horizontal pieces. By these means equilibrium could be restored after any extra oscillation on the part of the sledge and its burden.
All these manœuvres are remarkable for the skill and prodigality with which human strength was employed; of all the scientific tools invented to economise effort and to shorten the duration of a task, the only one they seem ever to have used was the most simple of all, the lever, an instrument that must have been invented over and over again wherever men tried to lift masses of stone or wood from the ground. Its discovery must, in fact, have taken place long before the commencement of what we call civilization, although its theory was first expounded by the Greek mathematicians.
In a relief in the palace of Assurnazirpal at Nimroud, there is a pulley exactly similar to those often seen over a modern well.[414] A cord runs over it and supports a bucket. There is no evidence that the Assyrians employed such a contrivance for any purpose but the raising of water. We cannot say that they used it to lift heavy weights, but the fact that they understood its principle puts them slightly above the Egyptians as engineers.