ast body of the sea
itself cannot immediately be let in here because the Quabos must take as
long a time to re-accustom themselves to its pressure as they did to
work out of it."

He spread the parchment sheet before us.

"Is this a roughly accurate plan of the city?" he asked Aga.

She inclined her lovely head.

"And this," indicating the cross, "is the spot where the Quabos will
break in?"

Again she nodded, shuddering.

"Then tell me what you think of this," said the Professor.

* * * * *

And he proceeded to sketch out a plan so simple, and yet so seemingly
efficient, that the rest of us gazed at him with wordless admiration.

"My friend, my friend," whispered Aga at last, "thou hast saved us.
Thou art the guardian hero of Zyobor--"

"Not too fast, Your Highness," interrupted the Professor with his frosty
smile. "I shall be much surprised if this little scheme actually saves
the city. We may find the rock so thick there that our task is
hopeless--though I imagine the Quabos picked a thin section for help in
their own plans."

A vague look came into his eyes.

"I must certainly get my hands on one of these monsters ... superhumanly
intelligent fish ... marvelous--akin to the octopus, perhaps?"

He wandered off, changed from the resourceful schemer to the dreamy man
of scientific abstractions.

The Queen gazed after him with wonder in her eyes.

"A great man," she murmured, "but is he--a little mad?"

"No, only a little absent-minded," I replied. Then, "Come on, Stanley.
We'll round up every able bodied citizen in Zyobor and get to work. I
suppose they have some kind of rock drilling machinery here?"

They had. And they strangely resembled our own rock drills: revolving
metal shafts, driven by gas turbines, tipped with fragments of the same
crystal that glittered so profusely in the palace walls. Another proof
that practically every basic, badly needed tool had been invented again
and again, in all lands and times, as the necessity for it arose.

With hundreds of the powerful men of Zyobor working as closely together
as they could without cramping each others movements, and with the whole
city resounding to the roar of the machinery, we labored at the defence
that might possibly check the advance of the hideous Quabos.

And with every breath we drew, waking or sleeping, we realized that the
cold blooded, inhuman invaders had crept a fraction of an inch closer in
t