harp on their outer edge. The
stab was to be made with the dagger shut, then the spring touched and
the split blades withdrawn.

Mr. Bernard replaced it, saying, that it would have served for sidearm
to old Suwarrow, who told his men to work their bayonets back and
forward when they pinned a Turk, but to wriggle them about in the wound
when they stabbed a Frenchman.

"Here," said the Doctor, "this is the thing you want."

He took down a much more modern and familiar implement,--a small,
beautifully finished revolver.

"I want you to carry this," he said; "and more than that, I want you to
practise with it often, as for amusement, but so that it maybe seen and
understood that you are apt to have a pistol about you. Pistol-shooting
is pleasant sport enough, and there is no reason why you should not
practise it like other young fellows. And now," the Doctor said, "I have
one other, weapon to give you."

He took a small piece of parchment and shook a white powder into it from
one of his medicine-jars. The jar was marked with the name of a mineral
salt, of a nature to have been serviceable in case of sudden illness in
the time of the Borgias. The Doctor folded the parchment carefully, and
marked the Latin name of the powder upon it.

"Here," he said, handing it to Mr. Bernard, "you see what it is, and you
know what service it can render. Keep these two protectors about your
person day and night; they will not harm you, and you may want one or
the other or both before you think of it."

Mr. Bernard thought it was very odd, and not very old-gentlemanlike,
to be fitting him out for treason, stratagem, and spoils, in this way.
There was no harm, however, in carrying a doctor's powder in his pocket,
or in amusing himself with shooting at a mark, as he had often done
before. If the old gentleman had these fancies, it was as well to humor
him.

So he thanked old Doctor Kittredge, and shook his hand warmly as he left
him.

"The fellow's hand did not tremble, nor his color change," the Doctor
said, as he watched him walking away. "He is one of the right sort."

CHAPTER XVI. EPISTOLARY.

Mr. Langdon to the Professor.

MY DEAR PROFESSOR, You were kind enough to promise me that you would
assist me in any professional or scientific investigations in which I
might become engaged. I have of late become deeply interested in a class
of subjects which present peculiar difficulty, and I must exercise
the privilege of ques