Hiding myself as best I could behind the rocky base of the pillar, I listened with all my ears.
I recognized the voices as those of Ker Karraje and Engineer Serko.
The two men stopped close to where I was lying, and continued their conversation in English--which is the language generally used in Back Cup.

I was therefore able to understand all that they said.
They were talking about Thomas Roch, or rather his fulgurator.
"In a week's time," said Ker Karraje, "I shall put to sea in the _Ebba_, and fetch the sections of the engines that are being cast in that Virginian foundry." "And when they are here," observed Engineer Serko, "I will piece them together and fix up the frames for firing them.

But beforehand, there is a job to be done which it seems to me is indispensable." "What is that ?" "To cut a tunnel through the wall of the cavern." "Through the wall of the cavern ?" "Oh! nothing but a narrow passage through which only one man at a time could squeeze, a hole easy enough to block, and the outside end of which would be hidden among the rocks." "Of what use could it be to us, Serko ?" "I have often thought about the utility of having some other way of getting out besides the submarine tunnel.

We never know what the future may have in store for us." "But the walls are so thick and hard," objected Ker Karraje.
"Oh, with a few grains of Roch's explosive I undertake to reduce the rock to such fine powder that we shall be able to blow it away with our breath," Serko replied.
It can easily be imagined with what interest and eagerness I listened to this.

Here was a ray of hope.It.was proposed to open up communication with the outside by a tunnel in the wall, and this held out the possibility of escape.
As this thought flashed through my mind, Ker Karraje said: "Very well, Serko, and if it becomes necessary some day to defend Back Cup and prevent any ship from approaching it----.