the chocks. In their great suits Norman and Hackett
were like two immense ape-figures in the uncertain light, to the eyes
of those about them.

"Well, all the luck," Harding told them. "You know I'm pulling for
you, but--I suppose it's useless to say anything about being careful."

"I seem to have heard the words," Hackett grinned, as he and Norman
shook the field superintendent's hand.

"It's all the craziest chance," Norman told the other. "And if we
don't come down in a reasonable time--well, you'll know that our
theory was right, and you can broadcast it or not as you please."

"I hope for your sake that you're dead wrong," smiled the official.
"I've told you two to get off the Earth a lot of times, but I never
meant it seriously."

Harding stepped back as the two clambered laboriously into the cramped
cabin. Norman took the controls, the door slammed, and as the chocks
were jerked back and the motor roared louder the long plane curved up
at a dizzy angle from the field into the dawn. Hackett waved a thick
arm down toward the diminishing figures on the field below; then
turned from the window to peer ahead with his companion.

The plane flew in a narrow ascending spiral upward, at an angle that
would have been impossible to any ship save an X-type. Norman's eyes
roved steadily over the instrument as they rose, his ears
unconsciously alert for each explosion of the motor. Earth receded
swiftly into a great gray concave surface as they climbed higher and
higher.

By the time the five-mile height was reached Earth's surface had
changed definitely from concave to convex. The plane was ascending by
then in a somewhat wider spiral, but its climb was as steady and sure
as ever. Frost begin to form quickly on the cabin's windows, creeping
out from the edges. Norman spoke a word over the motor's muffled
thunder, and Hackett snicked on the electrical radiators. The frost
crept back as their warm, clean heat flooded the cabin.

Ten miles--fifteen--they had reached already altitudes impossible but
a few years before, though it was nothing to the X-types. As they
passed the ten-mile mark, Hackett set the compact oxygen-generator
going. A clean, tangy odor filled the cabin as it began functioning.
Twenty miles--twenty-two--

* * * * *

After a time Norman pointed mutely to the clock on the instrument
board, and Hackett nodded. They were well within their time schedule,
having calculated