ed shut:
there was a click as its lock shot over. The sphere was a sealed ball
of metal.

Inside, David Guinness obeyed the automatic's imperious gesture and
pulled a shiny-handled lever slowly back, and the hush that rested
over the Mojave was shattered by a tremendous bellow, a roar that
shook the very earth. It was the disintegrating blast, hurled out of
the bottom in many fan-shaped rays. The coarse gray sand beneath the
machine stirred and flew wildly; the sphere vibrated madly; and then
the thunder lowered in tone to a mighty humming and the earth-borer
began to drop. Slowly it fell, at first, then more rapidly. The shiny
top came level with the ground: disappeared; and in a moment there was
nothing left but a gaping hole where a short while before a round
monster of metal had stood. The hole was hot and dark, and from it
came a steadily diminishing thunder....

* * * * *

For a long time no one in the earth-borer spoke--didn't even try
to--for though the thunder of the disintegrators was muted, inside, to
a steady drone, conversation was almost impossible. The three were
crowded quite close in the spherical inner control compartment. Sue
sat on a little collapsible stool by the bowed, but by no means
subdued, figure of Professor David Guinness, while Quade sat on the
wire guard of the gyroscope, which was in the exact center of the
floor.

The depth gauge showed two hundred feet. Already the three people were
numb from the vibration; they hardly felt any sensation at all, save
one of great weight pressing inwards. The compartment was fairly cool
and the air good--kept so by the automatic air rectifiers and the
insulation, which shut out the heat born of their passage.

Quade had been carefully watching Guinness's manipulation of the
controls, when he was struck by a thought. At once he stood up, and
shouted in the elderly inventor's ear: "Try the rockets! I want to be
sure this thing will go back up!"

Without a word Guinness shoved back the lever controlling the
disintegrators, at the same time whirling a small wheel full over. The
thudding drone died away to a whisper, and was replaced by sharper
thundering, as the stream of the propulsion rockets beneath the sphere
was released. A delicate needle trembled on a gauge, danced at the
figure two hundred, then crept back to one-ninety ... one-sixty ...
one-forty.... Quade's eyes took in everything.

"Excellent, Guinness!" he