"Directly all hands were aboard Palmer opened a valve, and I saw the pale green light filter through the glass of the conning-tower; we had sunk clear of the _Olive Branch's_ hull. We descended quite 80ft., in fact, almost to the bottom of the sea, for I could see the water discoloured by the muddy sediment caused by the rush of the still ebbing tide. Then the motors were started, and, once well away from the cruiser, Palmer hoisted the periscope, which hitherto had been housed within the submarine.
"'Now, then,' said he, 'you know a mine when you see one, so will you please stand by the conning-tower look-out; I'll keep the vessel on her course by means of the periscope.'
"So saying he descended a short iron ladder and took his stand before a small table coated with highly polished silver. This mirror reflected an erect, right image, or, in other words, a faithful reproduction of the horizon as seen from the surface.
"We were running at six knots, so that taking into consideration the strength of the ebb, our rate over the ground was a bare three knots, thus allowing an ample margin to bring up should we sight an obstruction."
"About 100ft., for the water was fairly translucent in the bright sunshine. Had it been dark we could have used a powerful searchlight.
"Suddenly I caught sight of a barrel-shaped object straining at its sinker and cable like a gigantic long-stalked mushroom. Palmer was instantly at my side, having ordered the motors to be eased down. The principle on which the torpedoes are fired is similar to that by which the guns are discharged on board this ship. I saw the slender, fish-shaped weapon leave the tube and glide towards the mark, but the target being a small one, and oscillating into the bargain, the torpedo missed it by a foot.
"The second shot was successful, and although I did not hear the detonation, the shock was sufficient to make the submarine lurch violently.
"This operation was repeated till we found ourselves right inside the harbour, the wharves and the shore being crowded with people attracted by the unwonted spectacle of the presence of a mysterious battleship in the offing."
"Then it's certain that all the mines have been destroyed?"