545, he regarded the isolated dwelling with considerable interest.

It was a two-story structure with a long extension in the rear, only one story in height.

With the exception of a dim light in this rear portion, the house was entirely dark, which led Mr.Rosenbaum to the conclusion that the landlady's private apartments were in this part of the building and remote from the room occupied by her lodger, which he surmised to be the front room on the second floor, a side window of which faced the cabin.
For more than an hour Mr.Rosenbaum remained at his post, and at last had the satisfaction of seeing the tall figure in the fur coat approaching down the dimly lighted street.

He ascended the steps of 545, let himself in with a night-key, and a moment later the gas in the upper front room was turned on, showing Mr.Rosenbaum's surmise to be correct.

For an instant the flaring flame revealed a pale face without the dark glasses, and with a full, dark beard tinged with gray; then it was lowered and the window blinds were closely drawn, precluding the possibility of further observation.
The face was like and yet unlike what Mr.Rosenbaum had expected to see; he determined upon a nearer and better view, without the dark glasses, before making any decisive move.
The following evening, as soon as it was dusk, found Mr.Rosenbaum again at the window of the deserted cabin, keenly observant of No.
545.