"Yes; things are coming to a crisis. The water was our sign, no doubt. It could hardly have been accidental. Mackenzie must have thrown a bucketful or two through the grating. It is dark outside at about the time of our last meal."
"Do you think the priests suspect us?"
"Who can say what goes on in their Chinese minds? The fellow didn't see the water: that is pretty certain. But I am troubled. In the chimney you heard running water above you, you said?"
"I am almost sure of it--perhaps the stream that runs across the plateau."
"If our chimney pierces its bed, we are doomed. There is not the ghost of a chance for us. The explosion you heard will be as a popgun to a whole Dreadnought armament in comparison with the result if the cavern is flooded. I take it that the water which fell into the pit was instantly decomposed by the rays. Only a little trickled over the brink; yet the explosion was powerful enough to hurl me against the wall. If water pours down in any volume, the whole place will be shattered, and we shall be cremated instantly in one enormous flame."
"Will you go up the chimney yourself presently, and see if I was right?" asked Forrester, aghast at the thought of this cataclysm.
"I will try. Thanks to you I am not nearly so much crocked as I was a few days ago. But we will wait a little longer than usual, to give the priest time to settle down if he is at all suspicious.... You were quite right, by the way, not to let me explain things to Wing Wu. He is so easily hypnotised that he might betray us at the first question. It will be time enough to tell him when our work is done."
Several hours later, they stole into the inner cavern, and when Forrester had placed the cross-bars in position, Beresford mounted the ladder, and climbed laboriously into the chimney from bar to bar. He carried the piece of pointed iron, with which he carefully probed the roof. Withdrawing the implement, he passed his fingers along it from the pointed end downwards.
"We are very near the surface," he called down softly. "You have destroyed all the rock. The iron has gone through two or three inches of clay, and then into loose earth. We can't risk employing the rays again. If the earth above collapsed en masse, it would smash through the screen and carry us with it into the pit. We must bore a hole gradually with the iron."
"What about the water?" Forrester asked.