It had altered its course, and instead of drifting away seaward was now travelling towards Duddingston, and making straight for Edinburgh, passing above the Russian camp. "Missed! _missed!_" Mackenzie shrieked, turning back the lever and arresting the discharge. "It's four miles off now, and we can carry seven and three-quarters to hit a fixed object. Remember, lads, the fate of Auld Reekie is now in your hands! Ready?" Again he bent and sighted the gun, raising the muzzle higher than the balloon so as to catch it on the ascent. The motor hummed louder and louder, the escaping air hissed and turned into liquid by the enormous pressure, then with a glance at the gauge he yelled "Fire!" and pulled back the lever. Dynamite shells, ejected at the rate of 50 a minute, rushed from the muzzle, and sped away. But the Demon of War, with its whirling propellers, continued on its swift, silent mission of destruction. "Missed again!" cried one of the men, in despair. "See! it's gone! We've--good heavens!--_why, we've lost it--lost it!_" Mackenzie, who had been glancing that moment at the gauges, gazed eagerly up, and staggered back as if he had received a blow. "It's disappeared!" he gasped. "_They've outwitted us, the brutes, and nothing now can save Edinburgh from destruction!_" Officers and men stood aghast, with blanched faces, scarce knowing how to act. The destructive forces in that controllable balloon were more than sufficient to lay the whole of Edinburgh in ruins; and then, no doubt, the enemy would attempt by the same means to destroy the British batteries on the neighbouring hills. Already, along the valleys fighting had begun, for rapid firing could be heard in the direction of Gilmerton, and now and then the British guns on the Braid Hills behind spoke out sharply to the Russians who had occupied Loanhead, and the distant booming of cannon could be heard incessantly from Corstorphine. Suddenly a loud, exultant cry from Mackenzie caused his companions to strain their eyes away to Duddingston, and there they saw high in the air the monster aërial machine gradually looming through the mist, a vague and shadowy outline. It had passed through a bank of cloud, and was gradually reappearing. "Quick! There's not a moment to lose!" shrieked Mackenzie, springing to the lever with redoubled enthusiasm, an example followed by the others. The motor revolved so rapidly that it roared, the gauges ran high, the escaping air hissed so loudly that Mackenzie was compelled to shout at the top of his voice "Ready?" as for a third time he took careful aim at the misty object now six miles distant. The War Demon was still over the Russian camp, and in a few moments, travelling at that high rate of speed, it would pass over Arthur's Seat, and be enabled to drop its deadly compounds in Princes Street. But Mackenzie set his teeth, and muttered something under his breath.