"In three minutes we shall be ready for action," he said, glancing at his watch; and then, turning a small wheel which raised the muzzle of the gun so as to point it at a higher angle in the direction of the sky, he waited until the space of time he had mentioned had elapsed. The officers stood aside conversing in an undertone. This man Mackenzie had invented this strange-looking weapon, and only one had been made. It had some months before been submitted to the War Office, but they had declined to take it up, believing that a patent they already possessed was superior to it; yet Mackenzie had nevertheless thrown his whole soul into his work, and meant now to show his superiors its penetrative powers, and put its capabilities to practical test. Again he glanced at his watch, and quickly pulled back another lever, which caused the motor to revolve at twice the speed, and the gun to emit a low hissing sound, like escaping steam. Then he stepped back to the officers, saying-- "I am now prepared. It will go up as straight and quickly as a rocket, but we must catch it before it ascends two miles, for the clouds hang low, and we may lose it more quickly than we imagine." The gunners stood in readiness, and the two officers looked away over Craigmillar towards the grey distant sea. Dawn was spreading now, and the haze was gradually clearing. They all knew the attempt would be made ere long, before it grew much lighter, so they stood at their posts in readiness, Mackenzie with his hand upon the lever which would regulate the discharge. They were moments of breathless expectancy. Minute after minute went by, but not a word was spoken, for every eye was turned upon the crest of a certain ridge nearly three miles away, at a point where the country was well wooded. A quarter of an hour had thus elapsed, when Mackenzie suddenly shouted, "Look, lads! _There she goes!_ Now, let's teach 'em what Scots can do." As he spoke there rose from behind the ridge a great dark mass, looking almost spectral in the thin morning mist. For a moment it seemed to poise and swing as if uncertain in its flight, then quickly it shot straight up towards the sky. "Ready?" shouted Mackenzie, his momentary excitement having given place to great coolness. The men at their posts all answered in the affirmative. Mackenzie bent and waited for a few seconds sighting the gun, while the motor hummed with terrific speed. Then shouting "Fire!" he drew back the lever. The gun discharged, but there was no report, only a sharp hiss as the compressed air released commenced to send charge after charge of dynamite automatically away into space in rapid succession! None dared to breathe. The excitement was intense. They watched the effect upon the Russian balloon, but to their dismay saw it still rapidly ascending and unharmed!