Glancing back over his shoulder after a minute or two, however, he drew up sheepishly. Of that strange apparition and those who had descended from it there was not a trace, not a shadow!

But the peculiar humming had recommenced, he realized in the next breath--and at the same instant he felt himself seized by invisible hands.

There was a struggle, but it was brief and futile. When it was over his captors became visible once more. They were singular little beings about four feet tall, with strange, wise, leathery faces, their heads grotesquely bald.

The humming had ceased again. The disc, too, was once more visible.

What happened next was something even more astounding, if there could be any further degrees of wonder possible for the utterly baffled young scientist. He felt himself lifted up, leaving the desert floor, whirling away toward that incredible phenomenon hovering there.

Another moment or two and he had been borne up through its trap-door opening, was standing in a dark s.p.a.ce bounded by solid metal walls.

Then he was thrust into a cylinder with several of his tiny guards, shot swiftly upward.

A door opened as they came to rest, and he was led out into a vast court of gleaming amber crystal. Something like a taxi slid up, with irridescent planes, and he was bundled into it, whirled away again.

Down broad, gleaming avenues they pa.s.sed, where similar traffic flowed densely, but under marvelous control. Towering skysc.r.a.pers loomed to right and left. Tier on tier of upper and lower boulevards revealed themselves, all crowded with automotive and pedestrian activity.

At length a stupendous concourse was reached. Thousands of these taxis and similar vehicles were parked along its broad flanks, while literal swarms of diminutive individuals circulated to and fro.

a.s.sisted from the vehicle that had brought him to this obvious center of the disc's activities. Kendrick was led into a monumental structure of jade-green stone that towered a full hundred, stories above the street level. There he was escorted into another of those projectilelike elevators, shot up, up--till at length it came to rest.

The door opened and he was led out into a small lobby of the same amber crystal he had observed before.

By now his guards had diminished to two, but he no longer made any effort to escape. Wherever this amazing adventure might lead, he was resolved to follow it through.

One of the guards had advanced to a jewelled door and was pressing a b.u.t.ton. In response, the door opened. A golden-robed, regal creature stood there.

Though dwarfed to four feet, like his fellow, he was obviously their mental superior to a prodigious degree. Not only was his symmetrical bald head of large brain content, but the finely-cut features of his parchment face bore the unmistakable stamp of a powerful intellect.

"_Ao-chaa!_" commanded this evident monarch of the disc, addressing the guards.

They bowed and departed, abruptly.

"My dear Kendrick!" the regal personage now said, in thin, precise English. "It is indeed a pleasure to welcome you to my humble quarters. Pray enter and make yourself comfortable."

Whereupon he ushered him into a dazzling apartment that was one vast mosaic of precious gems, indicated a richly carved chair, into which the young scientist dropped wonderingly.

"Now then, Professor," continued the mighty little dwarf, when he was seated in a chair even more sumptuous, "suppose we have a friendly little discussion. I have been much interested in your experiments on heat radiation. What you demonstrated this morning, in particular, was most absorbing. You have hit upon a rather profound scientific principle, yes?"

"Possibly," Kendrick admitted, quite conscious that he was being patronized.

"Oh, don't be modest, my dear fellow!" smiled the dwarf. "I am the last one to belittle your achievement. Indeed, it is because of it that I have invited you here to-day. Permit me to introduce myself, and to make clear one or two possibly perplexing matters. Then I am sure we shall have a most agreeable chat."

His name was Cor, he said, and he was in truth the monarch of this strange realm. His people had come from the one-time planet of Vada, far distant in the universe. A thousand years ago, this planet had been doomed by the approach of an alien star. Their great scientist, Ravv, had met the emergency by inventing the disc, into whose construction they had poured all their resources. The pick of their populace had been salvaged on this giant life-raft. The rest had perished when that destroying star had crashed down on the doomed Vada.

Since then these survivors and their descendants had been voyaging through s.p.a.ce on their marvelous disc. For hundreds of years they had given no thought to the future, content to drift on and on in the interstellar void, breathing an atmosphere produced artificially. But at length the inevitable had happened. This superb piece of mechanism devised by their super-genius, Ravv, was beginning to show signs of wear. Some of its mighty engines were nearing the exhaustion point.

Either they must soon find a planet comparable with the one they had once known, where they could pause and rehabilitate their machinery, or they must disintegrate and pa.s.s into oblivion.

Faced with that crisis, Cor had long been seeking such a planet. He had found it, at last, in the earth--and had resolved that this was where they were going to alight and transplant the civilization of ancient Vada, pending such time as they could take to s.p.a.ce again.

For some months now they had been hovering over various portions of the earth, studying its geography and its peoples, with the result that they had concluded the United States offered the most logical point for launching the attack. Once this country was subdued, they were in possession of the richest and most advanced section of the planet. The conquest of the rest of it could await their leisure.

With such an invasion in view, their scientists had mastered the language of the country. This had been accomplished very easily, since in addition to their power of mingling with the populace in an invisible form, they had the principles of radio developed to a high degree and were able to tune in on any station they wanted.

Kendrick sat there, stunned, as Cor followed his astounding revelation of their origin with this calm plan for the conquest of America, of the world. Why, of all people on earth, had he alone been singled out for this disclosure?

He asked the question now.

"My dear Professor, can't you really guess?" replied Cor, with that leathery smile. "Hasn't it dawned that you were a little too near our own field with that machine of yours? A trifle more research, a slightly different application--and you would have become a dangerous enemy."

"You--you mean--?"

"I mean there isn't a great deal of difference between the experiments you have been making and those our great Ravv once made. For instance, had you broadcast your heatricity, as you call it, instead of trying to transmit it on wires--well, picture a receiving apparatus in each home of the land, like your commercial radio sets. You would have become a billionaire, don't you see?"

Kendrick saw indeed. It was simple, so simple! Fool--why hadn't he thought of it?

"But your invention will never make you wealthy now, my dear fellow,"

Cor went on, tauntingly. "You will be our guest, here, until we have taken over your interesting country. After that, if there is any need for the broadcasting of heat, we will furnish it ourselves. We have those facilities, among others, fully developed. Would you care to see our plant?"

Kendrick naturally admitted that he would, so the dwarf led him through a rear door and up a winding flight of stairs. They emerged presently into a great laboratory housed in the gla.s.s-roofed pinnacle of the tower.

There he beheld a sight that left him breathless. Never before had he seen such an a.s.semblage of scientific apparatus. Its vastness and strangeness were fairly overpowering, even to a man as well versed in physio-chemical paraphernalia as he was.

Before his eyes could take in a tenth part of the spectacle, Cor had led him to the left wall.

"There," he said, "you will observe a development of your heat generator."

Kendrick looked--to see a long bank of large vacuum-tubes, each about three feet high and a foot wide, connected by a central shaft that caused series of little vanes in each of them to revolve at lightning speed.

Around the apparatus moved numerous small attendants, oiling, wiping, adjusting its many delicate parts.

"Well, what do you think now?" asked Cor.

Kendrick made no reply, though he was thinking plenty.

"You see, it is your invention, my dear Professor," the dwarf went on in his taunting voice, "only anteceded by a thousand years--and rather more perfected, you must admit."