The hour of the struggle approached. Every soul in Zyobor moved in a daze, with strained face and fear haunted eyes. Their proficiency in mental telepathy was a curse to them now: every one carried constantly, transmitted from the brains of the servant-fish outposts, a thought picture of that outer cavern in the murky depths of which writhed the thousands of crowding Quabos. Each mind in Zyobor was in continual torment.
Spared that trouble, at least, Stanley and the Professor and I walked down to the fortification we had so hastily contrived. It was finished. And none too soon: the vibration indicator in the palace vault told us that only two feet of rock separated us from the burrowing monsters!
The Professor's scheme had been to cut a long slot down through the rock floor of the city to the roof of the vast, mysterious body of water below.
This slot was placed directly in front of the spot in the city wall where the Quabos were about to emerge. As they forced through the last shell of rock, the deluge of water, instead of drowning the city, was supposed to drain down the oblong vent. Any Quabos that were too near the tunnel entrance would be swept down too.
In silence we approached the edge of the great trough and stared down.
There was a stratum of black granite, fortunately only about thirty feet thick at this point, and then—the depths! A low roar reached our ears from far, far beneath us. A steady blast of ice cold air fanned up against us.
The Professor threw down a large fragment of rock. Seconds elapsed and we heard no splash. The unseen surface was too far below for the noise of the rock's fall to carry on up to us.
"The mystery of this ball of earth on which we live!" murmured the Professor. "Here is this enormous underground body of water. We are far below sea level. Where, then, is it flowing? What does it empty into? Can it be that our planet is honeycombed with such hollows as this we are in? And is each inhabited by some form of life?"
He sighed and shook his head.