were stationed with sledges at
the doors and windows. The Quabos, able only to enter one at a time,
halted a moment and there was a badly needed breathing spell.

* * * * *

"We've got to find some drastic means of defence," said the Professor,
"or we won't last another three hours."

"If you asked me, I'd say we couldn't last another three hours anyway,"
replied Stanley with a shrug. "These fish have out-thought us!"

"Nonsense! There may still be a way--"

"A brace of machine-guns...." I murmured hopefully.

"You might as well wish for a dozen light cannon!" snapped the
Professor. "Please try to concentrate, and see if any effective weapon
suggests itself to you--something more available at the moment than
machine-guns."

In silence the three of us racked our brains for a means of defence.
Aga, leaving for a time the task of soothing her more hysterical
subjects, came quietly over to us and sat on the bench beside me.

Frankly I could think of nothing. To my mind we were surely doomed. What
arms could possibly be contrived at such short notice? What weapon
could be called forth to be effective against the thick glass helmets?

But as I glanced at Stanley I saw his face set in a new expression as
his thoughts took a turn that suggested possible salvation.

"Glass," he muttered. "Glass. What destroys it? Sharp blows ... certain
acids ... variation in temperature ... heat and cold.... That's it!
_That's it!_"

He turned excitedly to the Queen.

"I think we have it! At least it's worth trying. If there is any tubing
around...." He stopped as he realized he was talking in English, and
resumed stiltedly in Aga's own language.

"Hast thou, in the palace, any lengths of pipe like to that which the
Quabos drag behind them?"

"No ..." Aga began, her eyes round and wondering. Then she interrupted
herself. "Ah, yes! There is! In a vault near that of Kilor's there is a
great spool of it. He had it fashioned to carry air for one of his
experiments--"

"Come along!" cried Stanley. "I'll explain what I have in mind while we
dig up this coil of hose."

* * * * *

A score of Zyobite workmen were gathered at once. The length of
hose--made of some linen-like fabric of tough, shredded sea-weed and
covered with a flexible metal sheath--was cut into three pieces each
about fifty yards long. These were connected to three of the largest gas
vents of the palac