ittle of the
construction of the _Pioneer_, but I could now see that she was quite
different in design from the ordinary plane. A monoplane she was, but
the wing structure was abnormally short and of great thickness, and
there were a number of tubes projecting from the leading edge that gave
the appearance of a battery of small cannon. The body, like all planes
designed for travel in air-level six, was cigar-shaped, and had
hermetically sealed ports and entrance manholes. A cluster of the
cannon-shaped tubes enclosed the tail just back of the fins and rudder
and, behind the wing structure atop the curved upper surface of the
body, there was a sphere of gleaming metal that was probably three feet
in diameter.

* * * * *

Before I could formulate questions regarding the unusual features of the
design, we were within the _Pioneer's_ cabin and Hart Jones was engaged
in clamping the entrance manhole cover to its rubber seat. A throbbing
roar that penetrated our double hull attracted my attention and, looking
through a nearby porthole, I saw that the convoy of army planes had
taken off and was circling over the SF-22 in anticipation of her start.
Trim, speedy fighting ships these were, with heavy caliber machine-guns
in turrets fore and aft and normally manned by crews of twelve each. The
under surfaces of their bodies glistened smooth and sleek in the light
from the field, for the landing gears had been drawn within and the
openings sealed by the close-fitted armor plate that protected these
ordinarily vulnerable portions when in flight.

The SF-22 was ready to take off and the crowds were drawing back into
the obscurity beyond the huge circle of blinding light. One after
another her twelve engines sputtered into life, and ponderously she
moved over the field, gathering speed as the staccato barking of the
exhausts gradually blended into a smooth though deafening purr. The tail
of the great vessel came up, then the wheels, and she was off into the
night.

* * * * *

Hart Jones sat at a bewildering array of instruments that covered almost
the entire forward partition of the cabin. He pressed a button and the
starting motor whined for a moment. Then the single engine of the
_Pioneer_ coughed and roared. Slowly we taxied in the direction taken by
the SF-22, whose lights were now vanishing in the darkness. I saw George
open a valve on the wall and Hart stretched