Deep, dull, booming, ominous, the roar continued. The sail flapped idle on the mast. Stern could distinguish a long line of foam that slid away, past the boat, as only foam slides on a swift current.
He peered, in the gloom, to port; and all at once, far on the horizon, saw a thing that stopped his heart a moment, then thrashed it into furious activity.
Off there in a direction he judged as almost due northeast, a tenuous, rising veil of vapor blotted out the lesser stars and dimmed the brighter ones.
Even in that imperfect light he could see something of the sinuous drift of that strange cloud.
Quickly he lashed the tiller, crept forward and climbed the mast, his night-glasses slung over his shoulder.
Holding by one hand, he tried to concentrate his vision through the glasses, but they failed to show him even as much as the naked eye could discern.
The sight was paralyzing in its omen of destruction. Only too well Stern realized the meaning of the swift, strong current, the roar--now ever increasing, ever deepening in volume--the high and shifting vapor veil that climbed toward the dim zenith.
"Merciful Heaven!" gulped he. "There's a cataract over there--a terrible chasm--a plunge--to what? And we're drifting toward it at express-train speed!"