e," he said. "It's phone-equipped; you can tell me all about that
wild nightmare of yours while we jog along."

The white beam from the despatcher's tower had been on them while they
talked. Other planes were waiting on the field. Smithy smiled as he
settled the helmet over his head. "For a strictly unofficial flight,"
he thought, "we're getting darned good service."

He taxied past a hangar where uniformed men pointedly paid them no
attention. He swung the ship to the line as Airboard regulations
required.

"N-73" was painted on the monoplane's low wings that seemed scraping
the ground. "N-73 Clear!" the despatcher's voice radioed into Smithy's
ears. Then the seven-hundred-and-fifty-horsepower DeGrosse let loose
its voice as Smithy gunned her down the field.

* * * * *

Whatever doubts Colonel Culver may have had of Smithy's ability were
dissipated as they made their way cautiously through the free-flying
area under five thousand. Everywhere were mail planes, express and
passenger ships taking off for the transcontinental day run, and
private planes scattering to the smaller landing areas among the
flashing lights of the flat-topped business blocks. Among them Smithy
threaded his way toward the green-lighted transfer zone, where he
spiraled upward.

At ten thousand he was on his course. He set the gyro-control which
would fly the ship more surely than any human hands, and the air-speed
indicator crept up to the four hundred and fifty miles an hour that
Culver had promised. Not till then did he give the man in the forward
cockpit the details of his "nightmare."

He had not finished answering the other's incredulous questions when
he throttled down to slow cruising speed and nosed the ship toward a
distant expanse of sage-blurred sand.

Outside the restricted metropolitan area he had already dropped out of
the chill wind that struck them at ten thousand. Behind them and off
to the right was the gray rampart of the Sierra. Ahead a rough circle
of darker hills enclosed the great bowl he had learned to know as
Tonah Basin.

* * * * *

Some feeling of unreality in his own experiences must have crept into
his mind; unconsciously he had been questioning his own sanity. Now,
at sight of the sandy waste where he and Rawson had labored, with the
dark slopes of desolate craters looming ahead and a blot of burned
wreckage directly below to mark the site of t