REIGN OF HADRIAN (A.D. 117-138).--Hadrian, a kinsman of Trajan, succeeded him in the imperial office. He possessed great ability, and displayed admirable moderation and prudence in the administration of the government. He gave up the territory conquered by Trajan in the East, and made the Euphrates once more the boundary of the empire in that quarter. He also broke down the bridge that Trajan had built over the Danube, and made that stream the real frontier line, notwithstanding the Roman garrisons were still maintained in Dacia. Hadrian saw plainly that Rome could not safely extend any more widely the frontiers of the empire. Indeed, so active and threatening were the enemies of the empire in the East, and so daring and numerous had now become its barbarian assailants of the North, that there was reason for the greatest anxiety lest they should break through even the old and strong lines of the Danube and the Euphrates, and pour their devastating hordes over the provinces. More than fifteen years of his reign were spent by Hadrian in making tours of inspection through all the different provinces of the empire. He visited Britain, and secured the Roman possessions there against the Picts and Scots by erecting a continuous wall across the island. Next he journeyed through Gaul and Spain, and then visited in different tours all the remaining countries bordering upon the Mediterranean. He ascended the Nile, and, traveller-like, carved his name upon the vocal Memnon. The cities which he visited he decorated with temples, theatres, and other monuments. In the year 131, the Jews in Palestine, who had in a measure recovered from the blow Titus had given their nation, broke out in desperate revolt, because of the planting of a Roman colony upon the almost desolate site of Jerusalem, and the placing of the statue of Jupiter in the Holy Temple. More than half a million of Jews perished in the useless struggle, and the survivors were driven into exile--the last dispersion of the race. The latter years of his reign Hadrian passed at Rome. It was here that this princely builder erected his most splendid structures. Among these was the Mole, or Mausoleum, of Hadrian, an immense structure surmounted by a gilded dome, erected on the banks of the Tiber, and designed as a tomb for himself.