am crept along the lower deck and seeped up into
the control room. And then rose the fatal sound of rushing
water--water pouring into the submarine from outside!

For the violet beam was a heat ray--a weapon surface civilizations had
not yet developed. While the _NX-1's_ crew had stared at it in the
teleview, it had melted a hole in their bow.

Immediately the submarine lost trim, and the deck tilted ominously. In
the face of material danger--danger from a source he understood--the
commander became cool and methodical.

"Sea-suits on!" he snapped. "Then forward and break out steel
collision-mat and weld it in place! Every man! You, too, Sparks and
McKegnie!"

"But--but, sir!" stammered Graham. "Do you want them to get us with
their paralyzing ray?"

"You'd rather drown?" Wells flung back. Silenced, the first officer
donned his sea-suit, and in thirty seconds the rest of the crew had
theirs on and were cluttering clumsily forward.

* * * * *

Alone in the control room, Keith battled with the unbalancing flow of
water, maneuvering with all his skill in a futile attempt to keep the
_NX-1_ on even keel. The men forward worked with great speed, spurred
on by the realization that they were fighting death itself, but even
as they labored the submarine swung in ever increasing rolls and dips;
the great weight of water she had shipped slopped back and forth; her
bow went steadily down. Keith swept her forward tanks clean of water,
always conscious of the immobile, staring octopi submarine in the
teleview, watching them, it seemed, curiously, and not driving home
their advantage with additional bolts of the violet heat ray.

Despite her commander's frantic efforts, the _NX-1_ fluttered down
remorselessly; the cavern floor rose, and, sinking with them, came the
octopi craft, in slow mockery of a fighting plane pursuing its
stricken foe to the very ground....

She struck bottom with a soft, thudding jar, and settled on even keel.
At once Wells released the helm, jumped into his own sea-suit and
stumbled down to take command.

He found the steel collision-mat in place, and the welding of it
nearly completed. A few feathery trickles of water still seeped
through on each side, but under his terse directions the pumps were
soon draining it out. The weird figures of the crew in their sea-suits
looked like creatures from another planet as they rapidly finished the
job.

"All right--up to the