Grasping the wheel, Haverly signalled for full speed astern; the propellers began to revolve, and, slowly but surely, the submarine glided off the mud-bank into deep water. An instant’s pause while the engines were reversed, and then the Seal moved forward on the bosom of the subterranean river at ten knots to the hour. Between the heaving mud-flats she glided, from the surfaces of which arose a nauseous odour of decaying matter, and a dense, malarial vapour ascended, to lose itself in the inky darkness that veiled the cavern roof.
For here neither walls nor roof were visible. Nought met the eye but the water—wherein slimy water-snakes writhed and twisted—and the seething mud. Scarce a wave rippled the placid surface of the stream, save those occasioned by the passage of the Seal, and not a sound broke the profound stillness of the vast cavern but the purring note of the engines.
So two days went by, with nothing to disturb the dreary monotony of the depressing voyage. Ever the same muddy, grey prospect stretched before the explorers, and they had begun to wonder whether they should ever find a way out of this loathsome river, when something happened.
Haverly was at the wheel, the others being below, engaged in their several duties, when a shout brought them rushing into the turret.
“Look!” cried the American, pointing ahead.
The Seal had passed out of the river, and, before them, shimmering in the rays of the searchlight, rolled a vast, subterranean sea.
To starboard, a cable length away, a low, sandy shore was visible, clothed almost to the water’s edge with a weird and curious vegetation which sparkled and gleamed with a dazzling lustre.
Flinging open the door, Seymour stepped out on deck, quickly followed by Garth and the professor.
“The heart of the globe!” the latter cried excitedly. “A subterranean world! My friends, we have the honour to be the discoverers of an unknown world. Steer her close in, Silas; I am curious to know what manner of growths those are.”
There was cause for the old scientist’s excitement. An absolutely unknown world lay before them, untrodden—for aught they knew—by any human foot, a world whose stupendous size was veiled as yet from their knowledge by its weird and ghostly twilight.