and the feelings remain totally under control.

Brotherson was unusually active and alert that evening. He was
anxious to fit one delicate bit of mechanism into another, and he
was continually interrupted by visitors. Some big event was on in
the socialistic world, and his presence was eagerly demanded by one
brotherhood after another. Sweetwater, posted at his loop-hole,
heard the arguments advanced by each separate spokesman, followed by
Brotherson's unvarying reply: that when his work was done and he had
proved his right to approach them with a message, they might look to
hear from him again; but not before. His patience was inexhaustible,
but he showed himself relieved when the hour grew too late for further
interruption. He began to whistle--a token that all was going well
with him, and Sweetwater, who had come to understand some of his moods,
looked forward to an hour or two of continuous work on Brotherson's part
and of dreary and impatient waiting on his own. But, as so many times
before, he misread the man. Earlier than common--much earlier, in fact,
Mr. Brotherson laid down his tools and gave himself up to a restless
pacing of the floor. This was not usual with him. Nor did he often
indulge himself in playing on the piano as he did to-night, beginning
with a few heavenly strains and ending with a bang that made the
key-board jump. Certainly something was amiss in the quarter where peace
had hitherto reigned undisturbed. Had the depths begun to heave, or
were physical causes alone responsible for these unwonted ebullitions of
feeling?

The question was immaterial. Either would form an excellent preparation
for the coup planned by Sweetwater; and when, after another hour of
uncertainty, perfect silence greeted him from his neighbour's room, hope
had soared again on exultant wing, far above all former discouragements.

Mr. Brotherson's bed was in a remote corner from the loop-hole made by
Sweetwater; but in the stillness now pervading the whole building, the
latter could hear his even breathing very distinctly. He was in a deep
sleep.

The young detective's moment had come.

Taking from his breast a small box, he placed it on a shelf close
against the partition. An instant of quiet listening, then he touched
a spring in the side of the box and laid his ear, in haste, to his
loop-hole.

A strain of well-known music broke softly, from the box and sent its
vibrations through the wall.

It was answered in