An instant’s scrutiny showed Mervyn that the thing was true.
Shaken to its foundations by the force of the explosions, which moment by moment were becoming more frequent, the whole cliff was tottering to its fall. How long it would be ere it thundered down upon the hapless submarine none could tell.
“Full speed ahead!” Silas snapped, his voice recovering its strength under the excitement of the moment; “we must get out of this or we’re done.”
All saw the force of his words, and within two minutes the Seal was leaping forward like a flash of light, her whole hull quivering with the throb of the engines. Her pace was tremendous. The cliffs dashed past in a dazzling line on either side, and still the tottering mass to starboard hung poised, as though loth to crush the gallant vessel and her crew.
The moments seemed to crawl by, and each was laden with the suspense of a century. How long till this gorge shall end? was the cry of each of the comrades. How long till these rocky walls shall cease?
Then suddenly, a sheet of open water appeared ahead, and at the sight a simultaneous cry of relief went up. Another moment and the vessel would have been out of the gorge, and safe from the perils of the crumbling cliff; but in the very instant of her escape, like the crack of doom, a thunderous explosion volleyed through the canyon.
With the sound, the tottering wall of rock bent and swayed, then crashed downward with a deafening roar. Almost, the Seal was clear of the falling débris—almost, but not quite. A colossal boulder caught her stern, ripping the whirling propellers from their sockets, and smashing her steering gear to a mass of scrap-iron.
“Done!” Garth gasped, staggering under the shock; “the beastly thing’s snapped the propellers, and they were the only ones I had.”
The others did not take in the significance of this remark for some moments. They were too occupied in a scrutiny of the curious place the Seal had entered. It was a great circular basin or funnel, enclosed on every side by towering cliffs, and around it the water was sweeping in a giant eddy. Into this the vessel was instantly drawn, being helpless as any log in the whirling water.
Turning, the adventurers gazed towards the gorge through which they had come. It had ceased to be. The fall of the cliff had completely choked the passage, and the basin was now without outlet!