It is evident that before armies could look habitually to being transported across the Mesopotamian streams, wherever they might happen to strike them in their expeditions, by boats of these two kinds, either ferries must have been established at convenient intervals upon them, or traffic along their courses by means of boats must have been pretty regular. An Assyrian army did not carry its boats with it, as a modern army does its pontoons. Boats were commonly found in sufficient numbers on the streams themselves when an army needed them, and were impressed, or hired, to convey the troops across. And thus we see that the actual navigation of the streams had another object besides the military one of transport from bank to bank. Rivers are Nature’s roads; and we may be sure that the country had not been long settled before a water communication began to be established between towns upon the river-courses, and commodities began to be transported by means of them. The very position of the chief towns upon time banks of the streams was probably connected with this sort of transport, the rivers furnishing the means by which large quantities of building material could be conveniently concentrated at a given spot, and by which supplies could afterwards be regularly received from a distance. We see in the Assyrian sculptures the conveyance of stones, planks, etc. along the rivers, as well as the passage of chariots, horses, and persons across them. Rafts and round boats were most commonly used for this purpose. When a mass of unusual size, as a huge paving-stone, or a colossal bull or lion, had to be moved, a long, flat-bottomed boat was employed, which the mass sometimes more than covered. In this case, as there was no room for rower’s, trackers were engaged, who dragged the vessel along by means of ropes, which were fastened either to the boat itself or to its burden. [PLATE CXXXIII., Fig. 2.]