In the texts and inscriptions of the early period ships are referred to, and these were undoubtedly the only class of vessels employed on the canals for conveying supplies in bulk by water. The size of such ships, or barges, was reckoned by the amount of grain they were capable of carrying, measured by the _gur,_ the largest measure of capacity. We find vessels of very different size referred to, varying from five to seventy-five _gur_ and over. The larger class probably resembled the sailing barges and ferry-boats in use to-day,[26] which are built of heavy timbers and have flat bottoms when intended for the transport of beasts. In Babylon at the time of the First Dynasty a boat-builder's fee for constructing a vessel of sixty _gur_ was fixed at two shekels of silver, and it was proportionately less for vessels of smaller capacity. A boat-builder was held responsible for unsound work, and should defects develop in a vessel within a year of its being launched, he was obliged to strengthen or rebuild it at his own expense. Boatmen and sailors formed a numerous class in the community, and the yearly wage of a man in such employment was fixed at sixty _gur_ of corn. Larger vessels carried crews under the command of a captain, or chief boatman, and there is evidence that the vessels owned by the king included many of the larger type, which he employed for carrying grain, wool and dates, as well as wood and stone for building-operations. [Illustration: FIG. 43. ASSYRIAN RAFT OF LOGS ON THE TIGRIS. (From a bas-relief in the British Museum.)]