"

"I assure you I have a keen appreciation of the gravity of the
situation," Dennis replied seriously.

"Well," said Fuller, "I'll begin with an easy one--one that won't tax
your powers of observation beyond endurance."

"Yes," I urged, "let him down gently. He does his best."

"What profession does the owner of that knife follow?"

Hilderman and I laughed.

"We may as well count that answer as read," he said.

"There's a catch there, Dennis," I warned him. "The legal designation
is 'mariner.'"

"I don't think it is," said my friend.

"We won't quarrel about terms," laughed our host graciously. "Sailor
or seaman or deckhand will do just as well."

"No," said Dennis, "it won't. The owner of this knife is not a sailor
by profession."

"But," Fuller protested, "it must belong to one of my crew, and it is
obviously a seaman's knife."

"In that case," Dennis answered, "I think you'll find that you have a
man on board who is not a professional seaman in the ordinary use of
the term. I'll tell you what I think of this knife, shall I?"

"By all means," urged Hilderman and his friend together, and I began
to take a keen interest in this curious discussion, for I could see
that Dennis was no longer playing. He turned the knife over in his
hand, and looked up at Fuller.

"Mr. Fuller," he said quietly, "the owner of this knife is not a
sailor by profession. He is probably a schoolmaster. I can't be sure
of that, but I can say this definitely: he is a professional man of
some sort, possibly an engineer, but, as I say, more probably a
mathematical master. He is left-handed, has red hair, a wife, and at
least one child."

I shouted with laughter when I realised how thoroughly my friend had
pulled my leg, but I broke off abruptly when Hilderman sat bolt
upright, and his chair and Fuller's cigar fell unheeded on to the
deck. But in a second they took their cue from me, and roared with
laughter.

"Oh, excellent, Mr. Burnham," said Hilderman between his guffaws. "But
you forgot to mention that his sister married a butcher's assistant."

"Ah, but I don't admit she did," Dennis protested.

"I'm very much indebted to you for exposing this masquerader," said
Fuller. "I shall have the matter inquired into. But seriously, Mr.
Burnham, you made one extraordinary fluke in your deductions, which
almost took my breath away. I have a man on board with red hair, and
when the boat came into the harbour he was working about her