332 THE DECLINE AND FALL CHAP, to arms by the presence of clanger, and convinced of the intentions of Sapor to plant a Persian colony in their room, and to lead them away into distant and barbarous captivity. The event of the two former sieges elated their confidence; and exasperated the haughty spirit of the great king, who advanced a third time towards Nisibis, at the head of the united forces of Persia and India. The ordinary machines, invented to batter or undermine the walls, were rendered inef- fectual by the superior skill of the Romans ; and many days had vainly elapsed, when Sapor embraced a reso- lution worthy of an eastern monarch, who believed that the elements themselves were subject to his power. At the stated season of the melting of the snows in Armenia, the river Mygdonius, which divides the plain and the city of Nisibis, forms, like the Nile ", an inun- dation over the adjacent country. By the labour of the Persians, the course of the river was stopped below the town, and the waters were confined on every side by solid mounds of earth. On this artificial lake, a fleet of armed vessels, filled with soldiers, and with engines which discharged stones of five hundred pounds' weight, advanced in order of battle, and engaged, almost upon a level, the troops which defended the ramparts. The irresistible force of the waters was alternately fatal to the contending parties ; till at length a portion of the walls, unable to sustain the accumu- lated pressure, gave way at once, and exposed an ample breach of one hundred and fifty feet. The Persians were instantly driven to the assault, and the fate of Nisibis depended on the event of the day. The heavy- armed cavalry, who led the van of a deep column, were bishop of Edessa, were at least performed in a wortliy cause, the defence of his country. He appeared on the walls under the figure of the Roman emperor, and sent an army of gnats to sting the trunks of the elephants, and to discomfit the host of the new Senacherib. " Julian, Oral. i. p. 27. Though Niebuhr (fom. ii. p. 307.) allows a very considerable swell to the Rlygdonius, over which he saw a bridge of twelve arches ; it is difficult, however, to understand this parallel of a trifling rivulet with a mighty river. There are many circumstances obscure, and almost unintelligible, in the description of these stupendous water- works.
