"Not just yet, Bob, and so much the greater need that you should look
out the sharper. Give the ship plenty of room, and I'll let her run down
for the passage, square for the channel."

Bob now ran aft, telling the mate he had better go on the forecastle
himself and conn the ship through the passage, which was a place he did
not like. Mark was vexed that the change should be made just at that
critical instant, but bounding forward, he was between the knight-heads
in half a minute, looking out for the buoys. At first, he could not see
them; and then he most felt the imprudence of Bob's quitting his post in
such a critical instant. In another minute, however, he found one; and
presently the other came in sight, fearfully close, as, it now appeared
to our young mariner, to its neighbour. The position of the ship,
nevertheless, was sufficiently to windward, leaving plenty of room to
keep off in. As soon as the ship was far enough ahead, Mark called out
to Bob to put his helm hard up. This was done, and away the Rancocus
went, Mark watching her with the utmost vigilance, lest she should
sheer a little too much to the one side or to the other. He hardly
breathed as the vessel glided down upon these two black sentinels, and,
for an instant, he fancied the wind or the current had interfered with
their positions. It was now too late, however, to attempt any change,
and Mark saw the ship surging onward on the swells of the ocean, which
made their way thus far within the reefs, with a greater intensity of
anxiety than he had ever before experienced in his life. Away went the
ship, and each time she settled in the water, our young man expected to
hear her keel grating on the bottom, but it did not touch. Presently the
buoys were on her quarters, and then Mark knew that the danger of this
one spot was passed!