und-glass
narrowed and grew more intense. Now they could see only North America,
now only the United States and a portion of Mexico, and now only
Texas.

"Back--_back!_" cried Stoddard, as the rugged land loomed up, spread
into a panorama of towns and ranches. "We're descending too fast!
We're bound to crash, unless--"

But already the professor had touched the ascending valve and swung
the steering lever.

Up they zoomed again. Once more a portion of Mexico was visible on the
glass, and along the international border now they could see a winding
thread of silver.

"The Rio Grande!" exclaimed the young geologist. "Just follow it up
toward its source till we come to El Paso. There'll be a landing-field
there."

"Yes, undoubtedly." The professor was working in abstraction over the
unfamiliar controls. "Now if I can just hold us on our course...."

* * * * *

He succeeded, and presently a white city gleamed over the curving rim
of the horizon to the northwest, the tall chimneys of its smelters
throwing long shadows from the lowering sun beyond.

In a minute or two they were over it, at a height of perhaps twelve
miles--and now, as they began descending, its patchwork of buildings
and plazas unfolded like some great quilt below.

"There's the field!" cried Stoddard, pointing in the glass to a wide
clear space on the outskirts. "Can you make it, do you think?"

"We'll know soon!" was the grim answer, as Prescott worked frantically
now with his valves and levers. "It's a matter of balancing off our
flow of gases, of holding up buoyancy to the very last. A little too
much, or not enough, and--"

Breathlessly, as they descended, Stoddard peered into the glass. Now a
scene of excitement was visible below. Figures could be seen gazing
up, waving their arms, running about this way and that.

"They must think they're getting a visit from another planet," said
Stoddard. "Or that the end of the world has come!"

"Maybe it has, for us!" agreed the professor, gravely. "I'm afraid
we're going to crash. I can't seem to--"

Whatever he was going to add was lost in a sudden, rending concussion
that flung them violently down, and plunged the room into darkness.

* * * * *

Staggering to his feet a moment later, bruised and shaken, Stoddard
gasped out:

"Professor are you there? Are you all right?"

A groan answered him, and for a moment his heart sank, but