The Sword was a submersible boat of only twelve tons, and consequently much inferior to the tug, both in respect of dimensions and power.  Her screw was worked by a couple of dynamos fitted with accumulators that had been charged twelve hours previously in the port of St. George.  However, the Sword would suffice to take us out of this prison, to restore us to liberty—­that liberty of which I had given up all hope.  Thomas Roch was at last to be rescued from the clutches of Ker Karraje and Engineer Serko.  The rascals would not be able to utilize his invention, and nothing could prevent the warships from landing a storming party on the island, who would force the tunnel in the wall and secure the pirates!

We saw no one while the two men were conveying Thomas Roch to the Sword, and all got on board without incident.  The lid was shut and secured, the water compartments filled, and the Sword sank out of sight.  We were saved!

The Sword was divided into three water-tight compartments.  The after one contained the accumulators and machinery.  The middle one, occupied by the pilot, was surmounted by a periscope fitted with lenticular portholes, through which an electric search-lamp lighted the way through the water.  Forward, in the other compartment, Thomas Roch and I were shut in.

My companion, though the gag which was choking him had been removed, was still bound, and, I thought, knew what was going on.

But we were in a hurry to be off, and hoped to reach St. George that very night if no obstacle was encountered.

I pushed open the door of the compartment and rejoined Lieutenant Davon, who was standing by the man at the wheel.  In the after compartment three other men, including the engineer, awaited the lieutenant’s orders to set the machinery in motion.

“Lieutenant Davon,” I said, “I do not think there is any particular reason why I should stay in there with Roch.  If I can help you to get through the tunnel, pray command me.”

“Yes, I shall be glad to have you by me, Mr. Hart.”

It was then exactly thirty-seven minutes past eight.

The search-lamp threw a vague light through the water ahead of the Sword.  From where we were, we had to cross the lagoon through its entire length to get to the tunnel.  It would be pretty difficult to fetch it, we knew, but, if necessary, we could hug the sides of the lake until we located it.  Once outside the tunnel the Sword would rise to the surface and make for St. George at full speed.

“At what depth are we now?” I asked the lieutenant.

“About a fathom.”

“It is not necessary to go any lower,” I said.  “From what I was able to observe during the equinoctial tides, I should think that we are in the axis of the tunnel.”

“All right,” he replied.

Yes, it was all right, and I felt that Providence was speaking by the mouth of the officer.  Certainly Providence could not have chosen a better agent to work its will.