A permanent network of roads would be useless in a country like Egypt. The Nile here is the natural highway for purposes of commerce, and the pathways which intersect the fields suffice for foot-passengers, for cattle, and for the transport of goods from village to village. Ferry-boats for crossing the river, fords wherever the canals were shallow enough, and embanked dams thrown up here and there where the water was too deep for fordings, completed the system of internal communication. Bridges were rare. Up to the present time, we know of but one in the whole territory of ancient Egypt; and whether that one was long or short, built of stone or of wood, supported on arches or boldly flung across the stream from bank to bank, we cannot even conjecture. This bridge, close under the very walls of Zarû,[4] crossed the canal which separated the eastern frontier of Egypt from the desert regions of Arabia Petraea. A fortified enclosure protected this canal on the Asiatic side, as shown in the accompanying illustration (fig. 42). The maintenance of public highways, which figures as so costly an item in the expenses of modern nations, played, therefore, but a very small part in the annual disbursements of the Pharaohs, who had only to provide for the due execution of three great branches of government works,--namely, storage, irrigation, mining and quarrying. [Illustration: Fig. 42.--Canal and bridge, Zarû, Karnak.] [Illustration: Fig. 43.--Cellar, with amphorae.] [Illustration: Fig. 44.--Granary.]