and introduced his companions, and four delighted boys
found themselves blushingly shaking hands with New York's famous chief
of police, Arthur Woods. Briefly Captain Hardy stated the purpose of
his visit and related the story of the capture of the Elk City
dynamiters.

"I recall the incident distinctly," said the Commissioner. "The
newspapers were full of it. And I recall that when I read the story I
wished I had as accomplished and clever a squad of boys to help me with
some of my hard problems."

The four boys flushed with happiness. But they were too much
embarrassed to make any reply.

"Captain Hardy," said the Commissioner, "what is your plan of action?"

"We have none as yet. We are to work under the direction of the secret
service. But we have not seen Chief Flynn yet. The boys just arrived."

"Let me make one suggestion to you," said the Commissioner, turning
again to the boys. "Before you attempt to do any detective work make
yourselves familiar with the city. Get some maps and study them until
you know every street and alley. Take your maps and go over the city
on foot. Put several days in at it. Become acquainted with the
water-front, the piers, the surface cars, the subways, the ferries.
Learn the city so that you can get around rapidly. Make the
acquaintance of as many policemen, wireless operators, secret service
men, and other persons as you can. Don't forget that a kind deed or a
thoughtful act will help you to make friendships quicker than anything
else; and make all the friends you can. In police work you never know
who will be of assistance to you. And above all things don't talk.
Don't tell a living soul about your purpose or your plans. Let Captain
Hardy do that if it is necessary. Secrecy is absolutely essential to
the success of your work. Unless you can get along without betraying
yourselves you may as well go right back home. Remember the spies you
are after are also after you. If they learn what you are, they might
even take your lives."

"Commissioner Woods," said Captain Hardy, after a pause, "I have been
wondering whether or not these boys should have some kind of passes
that will enable them to get through the police lines. There may come
times when it is of the highest importance that nothing shall interfere
with them. What do you think about it?"

The Commissioner considered for a moment. "If I were sure they could
be trusted with----"

"They can," inter