The signal was read in a moment. The two girls
retreated to the middle of the boat to make room for Roger in the stern.

On and on they came. For an instant it seemed as if nothing could save
them, for an ugly cross wave hurled them straight towards the rocks.
But the next righted them as suddenly, lifting them high on its crest
and dashing them headlong towards the one spot where help awaited them.

Before they rose again a deft cast from Armstrong had sent the rope
across the bows within Roger's reach, while the doctor, with the other
end lashed round his body, was running at full speed towards the calmer
water of the cove.

For a moment the line hung slack, as a great back-wave lifted the boat
on its crest and carried it seawards. But suddenly the strain came,
carrying the two men on shore nearly off their feet, and grinding on the
gunwale of the boat with a creak which could be heard even above the
waves.

"Hold on now!" cried Armstrong, as a forward wave surged up behind the
boat.

All obeyed but Roger, who, seeking to ease the strain, began to haul in
on the rope. The wave tossed the boat up with a furious lurch, half
swamping it as it did so, and flinging it down again headlong into the
trough. When it rose once more the rope still held, and three of her
passengers were safe. But Roger was not to be seen.

With an exclamation which even the doctor, in the midst of his
excitement, could hear, Armstrong flung himself blindly into the chaos
of water. For a moment or two it seemed as if he had gone straight to
his fate, for amid the foam and lashing spray they strained their eyes
in vain for a glimpse either of him or his pupil.

Then he appeared high above their heads on the crest of a wave, striking
out to where, for one instant, an upstretched arm and nothing more rose
feebly from the water. The next moment, hurled thither as it seemed by
the wave, he had reached it, and was battling for dear life with the
surf that swept him back seaward.

By this time a few bystanders had ventured out on to the rocks, one of
them with a rope, which, after three vain attempts, fell within reach of
the exhausted pair. By its aid Armstrong piloted his senseless charge
into the calmer water of the cove, and the whole party, a few moments
later, were safe on _terra firma_.

CHAPTER NINE.

THE CAPTAIN RELIEVES GUARD.

When Mr Armstrong, having with some difficulty taken in who and where
he was, proceeded, a