Max replied by casting a bomb over the parapet. It exploded, killing half a dozen men. But this mob was not to be intimidated like the thieves. The bullets began to fly; fortunately the gathering darkness protected us. The crowd grew blacker, and more dense and turbulent. Then a number of stalwart fellows appeared, bearing a long beam, which they proposed to use as a battering-ram, to burst open the door, which had resisted all previous attacks. "Bring down one of the death bombs," said Max to the men in the Demon. Two stout fellows, belonging to the air-ship, carried down, carefully, between them, a great black sphere of iron. "Over with it!" cried Max. There was a crash, an explosion; the insurgents caught a whiff of the poisoned air; the men dropped the beam; there was a rush backward amid cries of terror, and the street was clear for a considerable space around the house. "Hurry, men, hurry!" cried Max. I peeped over the parapet. A number of the insurgents were rushing into a house three doors distant. In a few moments they poured out again, looking behind them as they ran. "I fear they have fired that house," I said to Max. "I expected as much," he replied, quietly. "Hurry, men, hurry," he again cried. The piles on the roof were diminishing rapidly. I turned to pass up bundles of my precious books. Another sound broke on my ears; a roaring noise that rapidly increased--it was the fire. The mob cheered. Then bursts of smoke poured out of the windows of the doomed house; then great arms and hands of flame reached out and snapped and clutched at the darkness, as if they would drag down ancient Night itself, with all its crown of stars, upon the palpitating breast of the passionate conflagration. Then the roof smoked; then it seemed to burst open, and vast volumes of flame and smoke and showers of sparks spouted forth. The blaze brought the mob into fearful relief, but fortunately it was between us and the great bulk of our enemies. "My God," said Max, "it is Cæsar's head!" I looked, and there, sure enough, upon the top of the long pole I had before noticed, was the head of the redoubtable giant. It stood out as if it had been painted in gory characters by the light of the burning house upon that background of darkness. I could see the glazed and dusty eyes; the protruding tongue; the great lower jaw hanging down in hideous fashion; and from the thick, bull-like neck were suspended huge gouts of dried and blackened blood. "It is the first instinct of such mobs," said Max, quietly, to suspect their leaders and slay them. They killed Cæsar, and then came after me. When they saw the air-ship they were confirmed in their suspicions; they believe that I am carrying away their treasure."