d each throwing a black shadow, fantastically shaped and
yet clearly defined on the grey-white sand behind it. There was no soil,
and all the softer kind of rock and stone had crumbled away ages ago.
Every particle of moisture had long since evaporated; even chemical
combinations had been dissolved by the alternations of heat and cold
known only on earth to the chemist in his laboratory.

Only the hardest rocks, such as granites and basalts, remained.
Everything else had been reduced to the universal grey-white impalpable
powder into which Zaidie's shoes sank when she, holding her husband's
hand, went down the ladder and stood at the foot of it--first of the
earth-dwellers to set foot on another world.

Redgrave followed her with a little spring from the centre of the ladder
which landed him with strange gentleness beside her. He took both her
gloved hands and pressed them hard in his. He would have kissed his
welcome to the World that Had Been if he could, but that of course was
out of the question, and so he had to be content with telling her that
he wanted to.

Then, hand in hand, they crossed the little plateau towards the edge of
the tremendous gulf, fifty-four miles across and nearly twenty thousand
feet deep, which forms the crater of Tycho. In the middle of it rose a
conical mountain about five thousand feet high, the summit of which was
just beginning to catch the solar rays. Half of the vast plain was
already brilliantly illuminated, but round the central cone was a
semicircle of shadow of impenetrable blackness.

"Day and night in this same valley, actually side by side!" said Zaidie.
Then she stopped and pointed down into the brightly lit distance, and
went on hurriedly, "Look, Lenox; look at the foot of the mountain there!
Doesn't that seem like the ruins of a city?"

"It does," he said, "and there's no reason why it shouldn't be. I've
always thought that, as the air and water disappeared from the upper
parts of the moon, the inhabitants, whoever they were, must have been
driven down into the deeper parts. Shall we go down and see?"

"But how?" she said.

He pointed towards the _Astronef_. She nodded her helmeted head, and
they went back towards the vessel.

A few minutes later the Space-Navigator had risen from her resting-place
with an impetus which rapidly carried her over half of the vast crater,
and then she began to drop slowly into the depths. She grounded gently,
and presently they were sta