rupted Captain Hardy. "Absolutely."

"Very well then."

The Commissioner pressed a button on his desk. A clerk entered the
room.

"Make out special police cards for Captain Hardy and these four lads,"
he said, naming the boys.

Again he turned to the young spy hunters. "The cards you are about to
get," he said, "will pass you by any policeman or put you through any
police line. Do not let any one know you have them and never use them
unless you absolutely must. It is best that not even the police should
know who you are. Be very careful not to lose your cards."

"We will make some little cloth bags," said Henry, "and carry the cards
in them inside of our underclothes."

"I see that you are resourceful," smiled the Commissioner.

The clerk returned with the cards and handed them to Captain Hardy.

"Before you go," said the Commissioner, "perhaps you would like to see
our wireless department and get acquainted with Sergeant Pearce who is
in charge of it."

He summoned a patrolman to guide them to the wireless rooms and wished
the boys success.

A few moments later Sergeant Pearce was showing them the apparatus.
Two operators sat at a wonderful Marconi outfit with receivers clamped
to their ears. In another room various instruments were installed here
and there, the walls were covered with diagrams of wireless instruments
and outfits, and lines of men were sitting at long tables with
receivers at their ears. It was the police wireless school. High
above the roof the aerial hung, suspended between the main dome and a
smaller dome at one end of the building.

"We are going to equip every station-house with wireless," said
Sergeant Pearce, "and the men you saw at work in the school are being
trained for operators. We have put wireless outfits on some of the
patrol-wagons and on the police boat _Patrol_, so you see we can get
into touch instantly with any precinct or with the _Patrol_ no matter
in what part of the harbor she may be. And when you have as big a
harbor as we have, with several hundred miles of waterfront, that means
something."

From Police Headquarters the little party went directly to the Post
Office Building, near the Brooklyn Bridge, to see Chief Flynn. He was
a large, heavy man, with black hair and eyes and a short mustache. He
shook hands with each of the party, and gave each a searching look. He
spoke quietly but right to the point.

"I had word from Washington about you," he