They relieved each other.  The bow was guard duty; the steering was light duty; the midships off duty.  It must be understood that, the great danger being sunken rocks, one man always crouched in the bow, with a paddle plunged below the surface, feeling for ambushes of the stony bushwhackers.  Occasionally all three had to labor, jumping into shallows, lifting the boat over beds of pebbles, perhaps lightening it of arms and provisions, perhaps carrying all ashore to seek a portage.

“It’s the best canew ‘n’ the wust canew I ever see for sech a voyage,” observed Glover.  “Navigatin’ in it puts me in mind ‘f angels settin’ on a cloud.  The cloud can go anywhere; but what if ye should slump through?”

“Och! ye’re a heretic, ‘n’ don’t belave angels can fly,” put in Sweeny.

“Can’t ye talk without takin’ out yer paddle?” called Glover.  “Mind yer soundings.”

Glover was at the helm just then, while Sweeny was at the bow.  Thurstane, sitting cross-legged on the light wooden flooring of the boat, was entering topographical observations in his journal.  Hearing the skipper’s warning, he looked up sharply; but both the call and the glance came too late to prevent a catastrophe.  Just in that instant the boat caught against some obstacle, turned slowly around before the push of the current, swung loose with a jerk and floated on, the water bubbling through the flooring.  A hole had been torn in the canvas, and the cockle-shell was foundering.

“Sound!” shouted Thurstane to Sweeny; then, turning to Glover, “Haul up the Grizzly!”

The tub-boat of bearskin was dragged alongside, and Thurstane instantly threw the provisions and arms into it.

“Three foot,” squealed Sweeny.

“Jump overboard,” ordered the lieutenant.

By the time they were on their feet in the water the Buchanan was half full, and the swift current was pulling at it like a giant, while the Grizzly, floating deep, was almost equally unmanageable.  The situation had in one minute changed from tranquil voyaging to deadly peril.  Sweeny, unable to swim, and staggering in the rapid, made a plunge at the bearskin boat, probably with an idea of getting into it.  But Thurstane, all himself from the first, shouted in that brazen voice of military command which is so secure of obedience, “Steady, man!  Don’t climb in.  Cut the lariat close up to the Buchanan, and then hold on to the Grizzly.”

Restored to his self-possession, Sweeny laboriously wound the straining lariat around his left arm and sawed it in two with his jagged pocket-knife.  Then came a doubtful fight between him and the Colorado for the possession of the heavy and clumsy tub.

Meantime Thurstane and Glover, the former at the bow and the latter at the stern of the Buchanan, were engaged in a similar tussle, just barely holding on and no more.

“We can’t stand this,” said the officer.  “We must empty her.”