en flame he waded to the inner rim of the
colossal ring. Below him hung the needle, a mere straight line of
white fire, a hundred feet in length. Eye-dazzling radiance
scintillated along it, waxing and waning with a curious throbbing
rhythm. The needle vibrated a little, but it pointed directly at the
red point of Mars, now almost directly overhead.

Repressing a shudder, Dan looked down at the complex and delicate
apparatus upon which the slender needle was mounted. It was a light
frame of white metal bars, with spidery coils and huge glowing tubes
and flimsy spinning disks mounted in it. The gleaming needle was
mounted much like a telescope at the top of the device, fully fifty
feet below him.

"Looks flimsy enough," Dan muttered. "I'll go through it like a
sixteen-inch shell! Who would have thought I'd end this way!"

* * * * *

He stepped back for a moment, and stood on the polished metal, hidden
to the waist in cold purple flame. Lest it impede his movements, he
tore the sheet from him and threw it aside. He let his eyes sweep for
a last time over the familiar constellations blazing so splendidly in
the black sky above. He had a pang of heartache, as if the stars were
old friends. His glance roved fondly over the dark, indistinct masses
of the island, and across the black plain of the sea.

"Well, no good in waiting," he muttered again. "Sorry I can't see
Helen. Hope she gets off all right."

He backed to the outer rim and drew a deep breath, like one about to
dive. Then, with set face, he sprinted forward. As he did so a
blinding flash of green light flickered up before him. He ducked his
head and leapt from the inner edge of the vast glowing ring.

For long seconds, it seemed, he was plunging down through space, feet
first. Air rushed screaming about his ears. But his mind was quite
calm, and registered an astonishingly large series of impressions.

He saw the delicate, gleaming machine rushing up to meet him, the
shimmering white needle swung on its top.

He took in the silent, dark plateau, with the masses of the great
machines rising like ominous shadows here and there, and the
mechanical monsters leaping busily about it, almost invisible in the
dim, ghostly radiance that fell from the purple ring.

He saw a vivid flame of green reach up past him from somewhere below.
He knew, without emotion or alarm, that he had been discovered, and
that it was too late for his disc