The dynamite charge was suspended about a foot above the surface of the watery, bubbling pool. Air was in that pool, air turned to transparent liquid by the intense cold. At -325° Fahrenheit air becomes a liquid. Here, exposed to the sunlight and the blue sky, a pool of liquified gas had collected from the incredible cold of the cold bomb below. The charge of explosive burst with a shattering roar. The echoes of the explosion had not died away when the two Dewey bulbs filled with T. N. T. fell into the bared ice cavity. A Dewey bulb is a combination of six vacuum bottles placed one outside the other. They are used for the keeping of liquid gases at a low temperature, but are obviously just as effective in protecting their contents from exterior cold. They fell some five yards apart and rolled, then were still. Their fuses sputtered. They went off together. A huge mass of shattered ice was thrown aside, and a dark, globular mass was exposed to view. Almost as soon as it was exposed to the air a crust of frozen air coated it, and liquified air began to trickle down its misshapen sides. There could be no doubt but that it was the cold bomb, invented by an insane genius to make him master of the world.
Those about the rim of the crater looked at it and turned away. Just as the intense heat of a blast furnace sears unprotected flesh even yards from its flame, so the incredible cold of the dark object pinched and wrung with its freezing rays. Not one man who looked upon the cold bomb but suffered from a deep frostbite.
"We can't approach that thing," said Teddy, with his hand over his eyes. "I'd just as soon, or sooner, try to tinker with burning thermite. We'll have to shoot armor-piercing shells at it. They'll freeze when they get near it, but the impact ought to crack the thing."
He motioned to the fur-clad soldiers to move back from the crater, and after a hasty consultation with the lieutenant went off toward the fort to ask for a small-caliber field gun.
The lieutenant paced back and forth restlessly. He was an ambitious young man. He did not relish taking orders from a civilian like Teddy. His eye fell on the heap of equipment that had been brought out from the fort. Two trench mortars, a trench catapult, a liquid-flame apparatus—one of the American inventions that had far outdone the original German flamenwerfers! There had been some thought of trying to reach a point just above the cold bomb and melting the ice down to it with liquid flame. That had been quickly proven impracticable, but the liquid-fire apparatus had not been sent back. The young lieutenant was not stupid. On the contrary, he was a singularly intelligent man. In a flash he saw how the liquid flame could have been used much more efficiently than Teddy's resistance coils about his explosive charges. The idea simply had not occurred to Teddy, or the young lieutenant, either. Now, however, he became all eagerness. If he succeeded in breaking up the cold bomb during Teddy's absence it would be a feather in his cap. If, in addition, he pointed out a method of dealing with the cold bombs superior to Teddy's plodding system, it would certainly mean his promotion and a very desirable reputation for himself in his profession.
He gave his orders briskly. The liquid-flame tank was set up, and began to spray out its stream of fire. The young lieutenant had it trained so that it passed just above the top of the ungainly cold bomb and grazed the upper edge. Then the two trench mortars were made ready for firing. The young lieutenant set them at their proper elevation himself. He was tremendously excited. He pointed the two mortars with the most meticulous precision. To aim them properly he had to expose his face again and again to the direct rays from the cold bomb, but he paid no attention to the searing, freezing rays.
The stream of liquid fire shot upward in a perfect parabola, and fell evenly, exactly, where it was aimed. The young lieutenant knew that a mortar bomb would be frozen by the intense cold if it were fired at the cold bomb direct, but his plan got around that difficulty. With the liquid fire playing just above and grazing the cold bomb, when the shell from the mortar struck the incredibly cold surface, both the shell and the cold bomb would be bathed in flame.
All was ready. The lieutenant fixed his eyes on the cold bomb and gave the signal. The two small trench mortars spouted flame. Two ungainly bombs rose high in the air and fell hurtling down toward the strange, frosted object at the bottom of the crater. One of the bombs would fall a little to the left. The other—squarely on top!
The cracking explosion of the bomb from the trench mortar was lost in the greater roar that followed it. Before the young lieutenant or any of his men could lift a finger they were enveloped by a colossal sheet of vaporized metal that seemed to fill the earth, the air, and all the sky. Of a weird and unearthly tint, the white-hot flame leaped into the air. It sprang up three thousand feet in hardly more than two seconds. The blast had the velocity of many rifle balls, and the withering heat of molten metal. The young lieutenant and his men were swept into nothingness in the fraction of a second. The crater they had worked for hours to blast out was as a puny ant hole beside the vast chasm that opened in the ice down to the red clay far beneath the bed of the Narrows. And New York shook and trembled from the shock of the terrific explosion.
CHAPTER VII.
Teddy was thrown down by the concussion, and fell in a heap against the commandant. He leaped to his feet and rushed to the window, from which the glass had disappeared. He saw the remnants of the sheet of flame dying away and saw that the low-lying cloud of mist had been blown from the surface of the ice. A gaping orifice, five hundred feet across, showed itself where Teddy and the lieutenant had been working. Of the lieutenant and his men no trace could be seen. Two or three of the little red flags that had marked the path through the mist still remained, however, and a small sledge was lying, overturned, beside the sledge route. Four tiny black figures lay in twisted attitudes beside the sledge. As Teddy looked one of them began to struggle feebly.
Teddy stared, speechless. For a moment he was dazed by the suddenness and the overwhelming nature of the calamity that had befallen the young lieutenant and his detachment. Only accident had saved him from a similar fate. Then his professional instinct re-asserted itself, and he began to piece together what he knew of the bomb. In a moment the solution came to him.
"Varrhus planned this," he said unsteadily. "He filled up his hollow cold bombs with solid iron. The heat that would come in would first melt and then vaporize the interior until the pressure inside was more than the still-solid crust could stand. And all that vaporized iron would burst out. What a fiend that man must be!"
An hour later, baffled and discouraged, he was sitting in the laboratory with his head in his hands, trying desperately to grapple with this new problem. The new cold bombs apparently could not be assailed without destruction of those who attacked them. It was impossible to imagine that volunteers could be found to sacrifice their lives to destroy each new bomb as it was placed. The horror of being annihilated by a blast of metallic vapor would deter men who would not hesitate to face death in a less terrible form. And Varrhus was evidently able to place them again nearly as fast as they were blown up. Telegrams announcing the explosion of the Jacksonville and Charleston ice floes lay before Teddy, supplemented by a cablegram from Panama saying that the Miraflores Locks had been destroyed by the blast when the Panama cold bomb had burst. Teddy was nearly certain that the next morning would find the exploded bombs replaced. Varrhus' black flyer was evidently capable of carrying a great weight at an immense speed. It also seemed able to reach an almost incredible height, from the fact that the second cold bomb had been dropped in the Narrows in broad daylight without the flyer having been sighted.