did not comfort him much;
however, he kept his thoughts to himself, and proposed that they should
keep as near the light as they could.

"Better keep where the roof's highest," suggested Vince. "We shall be
able to breathe more freely then."

After that they were both very silent, for they suffered horribly from
the dread that as soon as the entrance was entirely closed up by the
tide, they would be rapidly exhausting all the pure breathable air
shut-in; and so deeply did this impress them, that before long a
peculiar sensation of compression at the chest assailed them both, with
the result that they began to breathe more hurriedly, and to feel as if
they had been running uphill, till, as it is called, they were out of
breath.

Neither spoke, but suffered in silence, their brains busy with
calculations of how long it would be before it was high water, and then
how long it would take before the tide sank low enough for the mouth of
the cave to be open once more.

Vince probably suffered the more keenly after the light was shut out
entirely; but his sufferings were the briefer, for just when his breath
was shortest, and he was feeling that he must breathe more rapidly if he
wished to keep alive, he heard a loud plashing and wallowing some
distance farther in.

That it was a party of seals playing about he was certain, and in
imagination he saw them crawling up on to some piece of rock by means of
their flappers and plunging down again. Once he heard a pair of them
swimming in chase one of the other, blowing and uttering loud, sighing
noises as they came near, and then appeared to turn and swim back, to
climb up on the rock again, with the effect of dislodging others, which
sprang heavily into the water, sending little waves along big enough to
make the boat rock perceptibly.

This was just when Vince felt at his worst, and Mike was lying back in
the boat breathing hard and in the most hurried way.

It was singular that just then the recollection of a story he had once
read in a work belonging to his father came to Vince's mind. True or
false, it had been recorded that some French surgeons had been
discussing the effect of the imagination upon the human mind, and to
test for themselves whether its effects could be so strong as some
writers and experimentalists had declared, they obtained permission to
apply a test to a condemned convict.

Their test was as follows: It had been announced to the man that he was