ht as much as possible.

The momentary flare disclosed a square envelope standing on edge and
close in against the seat. Extinguishing the match, he caught it up.

It was of white linen of superior quality, without superscription, and
sealed; the contents were very light--a single sheet of paper, likely.

The handkerchief, the crushed roses, the unaddressed, sealed
envelope--the horse, the empty and deserted cab, standing before a
vacant lot, at one o'clock in the morning! Surely any one of them was
enough to stir the imagination; together they were a tantalizing
mystery, calling for solution and beckoning one on.

Harleston took another look around, saw no one, and calmly pocketed the
envelope. Then, after noting the number of the cab, No. 333, he gathered
up the lines, whipped the ends about the box, and chirped to the horse
to proceed.

The horse promptly obeyed; turned west on Massachusetts Avenue, and
backed up to his accustomed stand in Dupont Circle as neatly as though
his driver were directing him.

Harleston watched the proceeding from the corner of Eighteenth Street:
after which he resumed his way to his apartment in the Collingwood.

A sleepy elevator boy tried to put him off at the fourth floor, and he
had some trouble in convincing the lad that the sixth was his floor. In
fact, Harleston's mind being occupied with the recent affair, he would
have let himself be put off at the fourth floor, if he had not happened
to notice the large gilt numbers on the glass panel of the door opposite
the elevator. The bright light shining through this panel caught his
eye, and he wondered indifferently that it should be burning at such an
hour.

Subsequently he understood the light in No. 401; but then it was too
late. Had he been delayed ten seconds, or had he gotten off at the
fourth floor, he would have--. However, I anticipate; or rather I
speculate on what would have happened under hypothetical
conditions--which is fatuous in the extreme; hypothetical conditions
never are existent facts.

Harleston, having gained his apartment, leisurely removed from his
pockets the handkerchief, the roses, and the envelope, and placed them
on the library table. With the same leisureliness, he removed his light
top-coat and his hat and hung them in the closet. Returning to the
library, he chose a cigarette, tapped it on the back of his hand, struck
a match, and carefully passed the flame across the tip. After several
puffs,