lcano, even in death, was ages old; its cold desolation showing
plainly on the screen. No fires poured now from a hot throat; the
molten sea that once had raged within had hardened and choked that vast
throat with rock that had frozen to make one enormous plain. Ringed
about by the jagged sides of the tremendous volcano, the floor within
seemed smooth by comparison, except for another depression at its upper
edge.

Here was another and smaller crater inside the great ringed wall of
Hercules. The light of the sun struck slantingly across to throw one
side of the gigantic cup into shadow, while the opposite rim blared
brightly in the lunar dawn. And within the smaller crater, too, one side
was dead black with shadow.

Dead!--No moving thing--no sign of life or indication that life might
ever have been! A dead world, this!--its utter desolation struck Chet's
half-uttered exclamation to a hoarse whisper of dismay. In all the
universe what less likely place might one discover wherein to look for
man?

* * * * *

His gaze was held in fascinated hopelessness on the barren, mountainous
ring, on the inner inverted cone, on the shadow within that smaller
crater--_on a tiny pinpoint of light that was flashing there!_... He
hardly knew when he raised one trembling hand and pointed, while a voice
quite unlike his own said huskily:

"Look! Look! I told you it was so!... There! In that little
crater!--it's signaling! Three dots--now three dashes--three dots again!
The old S O S!--the old call for help! It's Haldgren!"

Again the screen showed the smiling scientist.

"Caught them just right," he said, "and glad to be of service. Now, if
there's anything else I can do--"

"Thanks!" said Chet in that same strained voice. "Thanks! There's
nothing else." A switch clicked beneath his hand, and once more the
screen was dark.

"Those dots and dashes! The old S O S! Who could doubt now?" Chet was
telling himself this when the Commander's voice broke in harshly.

"Even you must see the absurdity of this, Bullard. You have heard this
astronomer tell you what the rest of us knew for ourselves--that there
is no air on the Moon; that it is impossible for a human being to live
there. And you would have us believe that a man has lived there for five
years!

"But I am taking your distinguished record into account; I am
overlooking your insubordination and the folly of your reasoning.
Perhaps your feeling a