The elderly officer reddened, turned away without replying. d.i.c.k looked about him.

There was less machinery in this room. The iron pillar that he had seen came through the floor and terminated some five feet above it in another of the opaque gla.s.s domes, filled with iridescent fire. About it was a complicated arrangement of dials and gauges.

In the centre of the room was a sort of camera obscura. A large hood projected above a flat table, and an officer was half-concealed beneath it, apparently studying the table busily.

"Come, American, you shall see your navy on its way to destruction,"

said Von Kettler, beckoning d.i.c.k within the hood.

The officer stepped from the table, whose top was a sheet of silvered gla.s.s, leaving Von Kettler and d.i.c.k in front of it. d.i.c.k looked. At first he could see nothing but the vast stretch of sea; then he began to make out tiny dots at the table's end, terminating in minute blurs that were evidently smoke from the funnels.

"Your ships," said Von Kettler, smiling. "This is the dirigible." He pointed to another dot that came into sight and disappeared almost instantly. "They are a hundred and fifty miles away. Explain to your friends in Washington that our super-telescopic sights are based upon a refraction of light that overcomes the earth's curvature. It is simple, but it happens not to have been worked out until my Master commanded it."

d.i.c.k watched those tiny dots in fascination, mentally computing. At an average speed of fifty knots an hour, the squadron's steaming rate, they should be off the coast within three hours. The dirigible would take two, if it went ahead to scout, as was almost certain.

d.i.c.k stepped back from beneath the hood and glanced about him. If only his arms were not bound, he might do enough damage within a few seconds to put the deadlier machinery out of commission, if only the silvered mirror. He glanced about him. Von Kettler, interpreting his thought, smiled coolly.

"You are helpless, my dear Yankee pig," he said. "But there is more to see. Oblige me by accompanying me up to the top story."

He pointed to a ladder running up beside the iron pillar through an opening in the roof, and d.i.c.k, with a shrug of the shoulders, complied. He emerged upon a small platform, apparently protruding into vacancy. Far underneath he saw the clearing, and two airplanes on the tarmac, the aviators looking like beetles from that height. He looked out to sea and saw no signs of the fleet.

"You have heard of St. Simeon Stylites, Yankee?" purred Von Kettler.

"The gentleman who spent forty years of his life upon a tall pillar, in atonement for his sins? It is His Majesty's desire that you spend, not forty years, but two or three hours up here, meditating upon his grandeur, before returning to earth. It is also possible that you will witness something of considerable interest. Look out to sea!"

d.i.c.k turned his head involuntarily. He heard Von Kettler's laugh, heard the snap of a switch--then suddenly he was alone in the void.

At that snap of the switch, everything had vanished from view behind him, the building, even the platform on which he stood. His feet seemed to rest on nothing. Yet below him he could still see the airplanes, and more being wheeled out.

A sense of extreme physical nausea overcame him. He reeled, then managed to steady himself. He, too, was invisible to his own eyes.

Involuntarily he cried out. No sound came from his lips. He stood there, invisible in an invisible, soundless void.

For what seemed an unending period he occupied himself with endeavoring to obtain the sense of balance. Then, with a great effort, he managed to loosen the cords that bound his right arm to his side. A mighty wrench, and he had slipped them up above his elbow. His right lower arm was free.

He extended it cautiously, and his hand encountered a railing.

Instantly he felt more at ease. He began moving slowly around in a widening circle, and discovered that the platform was enclosed. The further side was, however, open, and he began sliding forward, foot by foot, to locate himself. Once his foot slipped over the edge, and he drew back hastily. He felt on the other side, and discovered that he was upon what seemed a plank walk, perhaps a hundred and fifty feet above the ground, with no rail on either side, and some six feet wide.

Very cautiously he shuffled his way along it. It was solid enough, although invisible, but more than once d.i.c.k walked perilously close to one edge or the other. At length he went down on his hands and knees, and proceeded, crawling, until his movements were arrested by what was unmistakably a door.

The plank bridge, then, connected the top stories of two buildings, but what the second was, there was no means of knowing. The door was barred on the other side, and did not yield an iota to d.i.c.k's cautious pressure. d.i.c.k felt the frame. Beyond was gla.s.s, reinforced with iron on the outside, the latter metal forming a sort of lattice work.

Cautiously d.i.c.k began to crawl up the rounded dome.

Foot by foot he made his way, clinging to the iron bars, until he felt that he had reached the point of the dome's maximum convexity. He wedged his feet against a bar and rested. Only now was it brought home to him that it would be impossible for him to find his way back to the plank.

A long time must have pa.s.sed, for, looking out to sea, he could see the squadron now, minute points on the horizon, exuding smudges of smoke. The dirigible was still invisible. The airplanes had either left the tarmac or had been wrapped in the gas-impregnated cloth, for both they and the aviators had vanished.

Suddenly d.i.c.k had an odd sensation that the iron was growing warm.

In another moment or two he had no doubt of it. The iron bar he clutched was distinctly warm; it was growing hot. He shifted his grasp to the adjacent bar and even in that moment the heat had increased perceptibly.

Suddenly there came a vibration, a sense of movement. d.i.c.k was being swung outward. The whole dome seemed to be dropping into s.p.a.ce. He dug his feet and fingers under the hot rods, and felt himself sliding over on his back.

Back--back, till he was lying horizontally in s.p.a.ce, and clutching desperately at the iron bar, which was growing hotter every moment.

The sliding movement ceased. It was as if the whole upper section of the gla.s.s dome had opened outward. But the heat of the bars was becoming unbearable, and gusts of hot air seemed to be proceeding from within.

Hot or not, d.i.c.k's only alternative was to work his way back to the stable portion of the dome, or to frizzle until he dropped through s.p.a.ce.

Clinging desperately to the bars, he began working back, reaching from bar to bar with his right hand and dragging his feet, with the clanking chain attached, from bar to bar also.

How he gained the base of the dome he was never able afterward to understand. The heat had grown intolerable; his hands were blistering.

Somehow he reached it. He rested a moment despite the heat. But to find the plank walk was clearly impossible. In another minute he must drop. Better that than to fry there like St. Lawrence on his griddle.

And then, just when he had resigned himself to that last drop, there came an unexpected diversion. Almost beside him a window was hung back. A man looked out. d.i.c.k saw one of the workmen in the blue blouses, and, behind him, within the dome, what seemed like an empty room.

d.i.c.k was slightly above the man. As his head and shoulders appeared, he let himself go, landing squarely across his back. He slid down his shoulders through the open window into the interior of the dome.

The man, flung against the frame of the window by the shock, uttered a piercing cry. Before he could recover his stand, or take in what had happened to him, d.i.c.k had gained his feet and leaped upon him. His right hand closed upon his throat. He bore him to the floor and choked him into insensibility.

CHAPTER XI

_In the Laboratory_

Not until the man's struggles had ceased, and he lay unconscious, panting, and blue in the face, did d.i.c.k release him. Then he looked about him.

Save for the workman, he was alone in a rotunda, open to the sky, and, as he had supposed, the whole upper portion of the dome had been flung back, leaving an immense aperture into which the sun was shining, flecking the interior with shafts of light. The temperature, despite the opening of the dome, must have been in excess of a hundred and twenty-five degrees.

There was nothing except an immense central shaft, up which ran a hollow pole of gla.s.s, cut off by the invisible paint at the summit of the dome. The inside of this gla.s.s pole was glowing with colored fires, and it was from this that the intolerable heat came, though its function d.i.c.k could not imagine.

One thing was clear: It was growing hotter each moment. To remain in that rotunda meant death within a brief period of time.

_And there was no way out!_ d.i.c.k glared around him, searching the gla.s.s walls in vain. No semblance of a stairway or ladder, even. Yet the workman must have entered by some ingress--if only d.i.c.k could discover it!

He began running round the interior of the dome in the brilliant sunshine, searching frantically for that ingress. And it was growing hotter! The sweat was pouring down his face beneath the invisible garment.

d.i.c.k was vaguely aware that the silence switch had been thrown in the room, for his feet made no sound, but the knowledge was latent in his mind. Two or three times he circ.u.mnavigated the interior of the dome, like a rat in a trap.

Then suddenly he saw a section of the flooring rise in a corner, and a workman in a blue blouse appear out of the trap door.