person at or near the house of Mrs. Clemmens, during
the time of the assault.

But before proceeding to satisfy himself in regard to these essentials,
he went again to the widow's house and there spent an hour in a careful
study of its inner and outer arrangements, with a view to the formation
of a complete theory as to the manner and method of the murder. He found
that in default of believing Mr. Hildreth the assailant, one supposition
was positively necessary, and this was that the murderer was in the
house when this gentleman came to it. A glance at the diagram on next
page will explain why.

The house, as you will see, has but three entrances: the front door, at
which Mr. Hildreth unconsciously stood guard; the kitchen door, also
unconsciously guarded during the critical moment by the coming and going
of the tramp through the yard; and the dining-room door, which, though
to all appearance free from the surveillance of any eye, was so situated
in reference to the clock at which the widow stood when attacked, that
it was manifestly impossible for any one to enter it and cross the room
to the hearth without attracting the attention of her eye if not of her
ear.

[Illustration: Diagram]

To be sure, there was the bare possibility of his having come in by the
kitchen-door, after the departure of the tramp, but such a contingency
was scarcely worth considering. The almost certain conclusion was that
he had been in the house for some time, and was either in the
dining-room when Mrs. Clemmens returned to it from her interview with
Mr. Hildreth, or else came down to it from the floor above by means of
the staircase that so strangely descended into that very room.

Another point looked equally clear. The escape of the murderer--still in
default of considering Mr. Hildreth as such--must have been by means of
one of the back doors, and must have been in the direction of the woods.
To be sure there was a stretch of uneven and marshy ground to be
travelled over before the shelter of the trees could be reached; but a
person driven by fear could, at a pinch, travel it in five minutes or
less; and a momentary calculation on the part of Mr. Byrd sufficed to
show him that more time than this had elapsed from the probable instant
of assault to the moment when Mr. Ferris opened the side door and looked
out upon the swamp.

The dearth of dwellings on the left-hand side of the street, and,
consequently, the comparative immunity fr