This it did, and was flying down-stream in a current as swift as a mill-race, when Hans checked it with the rope and checked too suddenly.

The boat flirted over and snubbed in to the bank bottom up, while Thornton, flung sheer out of it, was carried down-stream toward the worst part of the rapids, a stretch of wild water in which no swimmer could live.
Buck had sprung in on the instant; and at the end of three hundred yards, amid a mad swirl of water, he overhauled Thornton.

When he felt him grasp his tail, Buck headed for the bank, swimming with all his splendid strength.

But the progress shoreward was slow; the progress down-stream amazingly rapid.

From below came the fatal roaring where the wild current went wilder and was rent in shreds and spray by the rocks which thrust through like the teeth of an enormous comb.