be? Yes, there was no mistaking! The
other was Slade himself, commander of the hireling army of Plutocracy!

Out from the attacking 'plane jetted sadden spurts of fire. Gabriel
heard the zip-zip-zip of bullets; heard a ripping tear, as one of his
canvas wings was punctured--God help him, had that explosive bullet
struck a wire or a stay!

Then, maddened to despair; and burning with fierce rage against this
monster of the upper air that now was hurling death at him, he once more
"banked," brought his machine sharp round, and charged, full drive, at
the attacker!

This tactic for a second must have disconcerted the Air Trust
mercenaries. Gabriel's speed was terrific. With stupefying suddenness,
the _epervier_ loomed up ahead of him.

"Now!" he shouted. "Take this, from me!"

Half rising from his seat, he hurled his last remaining projectile full
at Slade, then wrenched his own 'plane off sharply to the left.

A thunderous concussion and a dazzling burst of light told him his
chance shot had been effective.

He got a second's vision of a shattered black mass, a tangle of girders,
wires, collapsed planes, that seemed to hang a moment in midair--of
whirling bodies--of wreckage indescribable. Then the broken debris
plunged with awful speed and vanished through the red-glowing mist.

Even as he shuddered, sickened at the terrible, though necessary deed,
the deed which alone could save him from swift death, an overwhelming
air-wave from the terrible explosion struck his speeding machine, the
machine captured in the Great Smokies from the Air Trust itself.

It heeled over like an unballasted yacht under the lash of a hurricane.
Vainly Gabriel jerked at wheel and levers; he could not right it.

As it seemed to come under control, a stay snapped. The 'plane swooped,
yawned forward and stuck its nose into an air-hole, caused by the vast,
uprising smoke and heat of the huge conflagration beneath.

Then, lost and beyond all guidance, it somersaulted, slid away down a
long drop and, whirling wildly over and over, plunged with Gabriel into
the glowing, smoking, detonating void!

CHAPTER XXXV.

TERROR AND RETREAT.

When, despite Flint's imperative orders, Slade failed to reopen the
lines of communication for him, before nightfall, and when President
Supple wired in code for a little more time in obeying Air Trust orders,
the Billionaire recognized that something of terrible menace now had
suddenly broken in upon