being among the stars on the eastern horizon.

"Hello," he muttered again. "So we're going to have a moon? In the last quarter, but still it ought to light me up from this beach."

A moment later the horns of the crescent had come above the black rim of the sea. Dan waited, swinging his arms and tramping up and down on the sand, until the silvery moon had cleared the horizon and illuminated the rugged face of the cliff with pale white radiance.

He chose a path to the top of the cliff and clambered up, emerging in a jungle-like thicket of brush. Picking his way with the greatest caution, yet scratching his naked skin most painfully, he made his way for a few yards through the brush to a point of vantage from which he could look about.

He was, he perceived, in a narrow valley or ravine, with rugged black walls rising sheer on either side. The silvery light of the crescent moon fell upon the rank jungle that covered the narrow floor of the canyon, which rose and dwindled as it penetrated inland.

azing up the canyon, Dan gasped in amazement at what he saw.

Mars, the red planet, hung bright and motionless, low in the western sky, gleaming with deep bloody radiance. Directly beneath it, bathed in the white light of the moon, was a bare, rocky peak that seemed the highest point of the island. And upon that highest pinnacle, that chanced to be just below the ruddy star, was an astounding machine.

Three slender towers, of a white metal that gleamed in the moonlight with the silvery luster of aluminum, rose from the rocky peak. They supported, in a horizontal position, an enormous metal ring. It must be, Dan reckoned swiftly, at least a hundred feet in diameter, and held a hundred feet above the summit of the mountain.

The huge ring gleamed with a strange purple radiance. A shimmering mist of red-violet light surrounded it. An unknown force seemed to throb within the mighty ring, drawing the mantle of purple haze about it.

And suspended inside the ring and below it was a long, slender needle of dazzling white light. To Dan, from where he stood in the canyon, it seemed a fine, sharp line, though he knew it must be some kind of pointer, luminous with the strange force pulsing through it.

The strange needle wavered a little, with quick, uncertain motions. The brilliance of its light varied oddly; it seemed to throb with a queer, irregular rhythm.

And the gleaming needle pointed straight at the planet Mars!

Dan stood a long time, watching the purple ring upon the silver towers, with the shining white needle hanging below it. He stared at Mars, glowing like a red and sinister eye above the incredible mechanism.

His mind was in a wild storm of wonder shot with fear. What was the meaning of the gleaming ring and needle? What connection did this great device have with the signal of distress from the cliff, and the green fire that had destroyed the Virginia? And why did the glowing needle point at Mars?

e did not know when he first began to hear the sound. For a time it was merely part of the strange mystery of the island, only another element in the atmosphere of fear and wonder that surrounded him. Then it rose a little, and he became suddenly sharply conscious of it as an additional menace. The sound was not loud, but deep and vibrant. A whir or hum, like that of a powerful, muffled motor, but deeper than the sound of any motor man has ever made. It came down the gorge, from the direction of the machine on the mountain.

That deep, throbbing noise frightened Dan as none of his previous experiences had done. Shivering from fear as much as from cold, he crouched down beside a huge boulder in the edge of the tangle of brush that covered the bottom of the ravine. His heart pounded wildly. He was in the clutches of an unreasoning fear that some terrible Thing had seen him, and was about to seek him out. For a moment he had to use all his will to keep himself from panic flight through the brush. The unknown is always terrible, and he had invaded the domain of a force he could not understand.

In a moment, however, he recovered himself. He would be as safe there in the jungle, he thought, as anywhere on the island. He thought of starting a fire, then realized that he had no matches, and that he would not dare to make a light if he were able. He pulled a few handfuls of dry grass to make a sort of bed, upon which he huddled up, thanking his lucky stars that the island was in semi-tropical latitudes.

His mind returned again to the riddles that confronted him: the green flash and the strange mechanism on the peak. He recalled fantastic stories he had read, of hermit scientists conducting amazing experiments in isolated parts of the world. Presently he decided that something of the kind must be on foot here.

"The green flash is a sort of a death ray," he summed up, aloud. "And they shoot it from that bright needle. No wonder they don't want to be bothered! Somebody may be fixing to upset civilization!

"But it's queer that the needle points at Mars...."

Of this last fact, which might have been a clue to the most reasonable solution of the mystery, if a rather astounding one, he was able to make nothing. In fact, huddled up on his pile of grass in some degree of comfort, he presently went to sleep, still pondering in vain upon this last clue.

e was awakened by a soft, insistent purring sound, rather like that of a small electric motor run without load at very high speed. Recollection of the night's events came abruptly to him, and he sprang to his feet in alarm, finding his muscles sore and stiff from his cramped position.

From one side Dan heard the rumble of thunder, and, glancing up, saw that the sky above the sea was overcast with a rolling mass of dark, menacing clouds. There was a strange portentous blackness about these storm clouds that filled him with a nameless fear.

Suddenly he was struck with the thought that it was not thunder that had wakened him. The noise he had heard had not the rumbling or booming quality of thunder. As he stood there he again became conscious of the low, whirring sound, behind him. He whirled around to face it. The shock of what he saw left him momentarily dizzy and trembling—though undoubtedly his surroundings had much to do with its effect upon him.

The sound came from a glistening metal machine which stood half-hidden in the brush a dozen yards away looking at him!

The thing was made of a lustrous, silvery metal, which Dan afterwards supposed to be aluminum, or some alloy of that metal. Its gleaming case was shaped more like a coffin, or an Egyptian mummy-case, than any other object with which he was familiar, though rather larger than either.

That is, it was an oblong metal box, tapering toward the ends, with the greatest width forward of the middle. Twin tubes projected from the end of it, lenses in them glistening like eyes. Just below them sprang out steely, glistening tentacles several feet long, writhing and twitching as if they were alive. The tangle of green brush hid the thing's legs, so that Dan could not see them.

uddenly it sprang toward him, rising ten feet high and covering half the distance between them. It alighted