ndlady cordially. "Any friends of Mr. Flynn's are
welcome. Your rooms are ready for you. Mr. Flynn said you wanted to be
together, so I have given you the entire top floor."

She led the way up one narrow stairway after another until the party
reached the top floor. There she threw open the door to the front room
and withdrew.

An exclamation of pleasure burst from the lips of the four boys. The
shabby exterior of the house and the dim and dingy hallways through which
they had come gave no hint of the cozy comfort that awaited them. The
room they now entered was of generous size, with soft gray wallpaper and
white woodwork. Along one side ran low, well-filled book-shelves. In
the middle of the opposite wall, with fire-making materials already piled
in it, was a small open grate, surmounted by an attractive mantel of
white woodwork. There were a writing-table, a comfortable couch, and
easy chairs. And what was most unusual for a city house, the room
possessed windows on three sides--two overlooking the street and one
giving a view over the housetops on either side. A door at the rear
opened into a second room that was equipped as a writing room, with a
broad table and several straight-backed chairs. Here, too, was an open
grate set in a white mantel. In the room behind this were a number of
cots. Back of all was the bath room. A snugger and more comfortable
place it would have been hard to find. But nowhere was there anything
that suggested a wireless outfit.

The boys looked at one another questioningly. "He said there was an
outfit here," said Lew, "so there must be. But I don't see where it can
be."

"It would be somewhere by itself," said Roy, "so that the operator
wouldn't be disturbed. It must be on another floor."

"But if we are to keep a twenty-four-hour watch," argued Henry, "it ought
to be right in our apartment."

"Let's look at the aerial, anyway," suggested Lew.

A door at the end of the hallway quite evidently led to the roof. They
had noticed it as they followed their landlady up the stairs. Willie led
the way through it and the boys found themselves on the roof, which, like
the roofs of most city houses, was flat. Like its neighbors, also, this
roof was encumbered with a number of long, wire clothes-lines, but the
boys found nothing that suggested an aerial to them. Puzzled, they
returned to their apartment.

Presently there was a rap at the door. Captain Hardy opened it