se, standing two stories higher than any other structure in the block. Like most of its neighbors it had evidently seen better days. In places the brownstone front was cracked and gre

rade was battered and dirty. Altogether i

opened the door e

o your place," said Captain Hardy. "We sh

m Washington that he 'phoned m

a

's are welcome. Your rooms are ready for you. Mr. Flynn said you

r until the party reached the top floor. There she

all, 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 re

e said there was an outfit here," said Lew, "so

Roy, "so that the operator wouldn't be

ur-hour watch," argued Henry, "it

he aerial, anywa

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 encum

ened it and a man dressed as a waiter, whom they had se

w you your out

g outward and came to rest on the writing-table, revealing a compact but wonderfully well-equipped wireless outfit, including even a

rding-house is this

the man. "This is a sort of headquarters

aerial?" dem

l see it-that is you will if

se wire clothes-li

waiter with a smile. "But I guess there

owded round it, sliding the coil, shifting the condenser, examining this and

of you will have to listen in six hours a day. If we divide the watc

experienced operator, Henry. After the others had seen him take his seat

Central City, Henry had heard this station send forth the time signals at ten o'clock; and during his brief period as radio man for Uncle Sam he had often talked with Arlington, both sending and receiving messages from the great station. But though he recognized the voice, he did not know the language he heard; for Arlington was flinging abroad a message in the secret code of the navy. Press messages and commercial communications were buzzing through the air like swarms of bees. Orders to departing steamships came surging over his line. Suddenly a strong whining note filled the

n three hundred meters' wave length. Instantly the room that had hummed with voices grew silent as a cave. No message, no vibrations, no whisper of sound came to his waiting ears. For three hours he sat, continually shifting his coils, but

the silence of the great forest. Here the watchers would be more comfortable, but the vigil was likely to be as tedious and trying as their watch in the Pennsylvania mountains had proved. But that watch had been rew

section he discovered was filled with maps and guide-books and local histories, not only of New York but also of other American cities. He found a large-scale map of the metropolis and spread it o

d elevated car lines. Together they located the tunnels and the ferries. They studied the harbor and the different shipping districts, coming quickly to know where the transatlantic liners docked, where the coastwise steamers were berthed, and where tramp steamers co

of Manhattan, Staten Island, and finally the Jersey shore, searching always for what would lend itself to spy

bway and surface and elevated trains, crossed the ferries, rode in the sightseeing motors, visited the bridges, the museums, the public buildings, and within a short time knew more about the topography and geography of the city than nine-tenths of the people wh

eek passed. Then another went by. But excepting for one or two snatches

on from which the signals came. It was well that Roy was a fast operator, for the message that followed came with such rapidity that it taxed Roy's ability to catch it. But he managed to get every letter. When the message was ended, Roy reached for his list of stations and rapidly ran through it. The stations he had overheard were not listed. T

ce to Chief Flynn," he said. "He may want to ask some que

spite the training in the geography of the city, Roy had become confused and gotte

hould wait a while," panted Roy, breathless from running up the stairs. "And th

letters Roy had picked out of the air

P S

O L

R E

T F

ead of across,"

a moment more, then read aloud: "