struction, flashed through
the spot where they would have been had they held their former course.

But powerful as were the propellant forces and fiercely though Costigan
applied them, the denizens of the deep clamped a tractor ray upon the
flying vessel before it had gained a mile of altitude. Costigan aligned
his every driving projector as his vessel came to an abrupt halt in the
invisible grip of the beam, then experimented with various dials.

"There ought to be some way of cutting that beam," he pondered audibly,
"but I don't know enough about their system to do it, and I'm afraid to
monkey around with things too much, because I might accidentally release
the screens we've already got out, and they're stopping altogether too
much stuff for us to do without them right now."

He frowned as he studied the flaring defensive screens, now radiating an
incandescent violet under the concentration of the forces being hurled
against them by the warlike fishes, then stiffened suddenly.

"I thought so--they _can_ shoot 'em!" he exclaimed, throwing the
lifeboat into a furious corkscrew turn, and the very air blazed into
flaming splendor as a dazzlingly scintillating ball of energy sped past
them and high into the air beyond.

Then for minutes a spectacular battle raged. The twisting, turning,
leaping airship, small as she was agile, kept on eluding the explosive
projectiles of the fishes, and her screens neutralized and re-radiated
the full power of the attacking beams. More--since Costigan did not need
to think of sparing his iron, the ocean around the great submarine began
furiously to boil under the full-driven offensive beams of the tiny
Nevian ship. But escape Costigan could not. He could not cut that
tractor beam and the utmost power of his drivers could not wrest the
lifeboat from its tenacious clutch. And slowly but inexorably the ship
of space was being drawn downward toward the ship of ocean's depths.
Downward, in spite of the utmost possible effort of every projector and
penetrator, and the two Terrestrial spectators, sick at heart, looked
once at each other. Then they looked at Costigan, who, jaw hard set and
eyes unflinchingly upon his plate, was concentrating his attack upon one
turret of the green monster as they settled lower and lower.

"If this is ... if our number is going up, Conway," Clio began,
unsteadily.

"Not yet, it isn't!" he snapped. "Keep a stiff upper lip, girl. We're
still breathing air, an