one, as I did to your friend Mr.
Cary, for information and assistance, and I have been advised by those
who know you here to be perfectly frank. You are not at present an
object of suspicion to the local police, who assure me, that though
you are known to have access to much secret information, yet that you
have never made any wrongful use of it. You have, moreover, been of
great assistance on many occasions both to the military and naval
authorities. Therefore, though my instinct would be to lock you up
most securely, I am told that I mustn't do it."

"You are very frank," said I. "But I bear no malice. Ask me what you
please, and I will do my best to answer fully."

"I ought to warn you," said he, with obvious reluctance, "that
anything which you say may, at some future time, be used in evidence
against you."

"I will take the risk, Mr. Dawson," cried I, laughing. "You have done
your duty in warning me, and you are so plainly hopeful that I shall
incriminate myself that it would be cruel to disappoint you. Let us
get on with the inquisition."

"You are aware, Mr. Copplestone, that a most important part of my work
consists in stopping the channels through which information of what is
going on in our shipyards and munition shops may get through to the
enemy. We can't prevent his agents from getting information--that is
always possible to those with unlimited command of money, for there
are always swine among workmen, and among higher folk than workmen,
who can be bought. You may take it as certain that little of
importance is done or projected in this country of which enemy agents
do not know. But their difficulty is to get it through to their
paymasters, within the limit of time during which the information is
useful. There are scores of possible channels, and it is up to us to
watch them all. You have already shown some grasp of our methods,
which in a sentence may be described as unsleeping vigilance. Once we
know the identity of an enemy agent, he ceases to be of any use to the
enemy, but becomes of the greatest value to us. Our motto is: Ab hoste
doceri." He pronounced the infinitive verb as if it rhymed with
glossary.

"You are quite a scholar, Mr. Dawson," remarked I politely.

"Yes," said he, simply. "I had a good schooling. I need not go into
details," he went on, "of how we watch the correspondence of suspected
persons, but you may be interested to learn that during the three
weeks which I have passed