Sweetwater seemed to decide for the rear, for leaving George, he stepped down the hall into the court beyond, where George could see him casting inquiring glances up at the walls above him.  Another tenement, similar to the one whose rear end he was contemplating, towered behind but he paid no attention to that.  He was satisfied with the look he had given and came quickly back, joining George at the foot of the staircase, up which he silently led the way.

It was a rude, none-too-well-cared-for building, but it seemed respectable enough and very quiet, considering the mass of people it accommodated.  There were marks of poverty everywhere, but no squalor.  One flight—­two flights—­three—­and then George’s guide stopped, and, looking back at him, made a gesture.  It appeared to be one of caution, but when the two came together at the top of the staircase, Sweetwater spoke quite naturally as he pointed out a door in their rear: 

“That’s the room.  We’ll keep a sharp watch and when any man, no matter what his dress or appearance comes up these stairs and turns that way, give him a sharp look.  You understand?”

“Yes; but-”

“Oh, he hasn’t come in yet.  I took pains to find that out.  You saw me go into the court and look up.  That was to see if his window was lighted.  Well, it wasn’t.”

George felt non-plussed.

“But surely,” said he, “the gentleman named Brotherson doesn’t live here.”

“The inventor does.”

“Oh!”

“And—­but I will explain later.”

The suppressed excitement contained in these words made George stare.  Indeed, he had been wondering for some time at the manner of the detective which showed a curious mixture of several opposing emotions.  Now, the fellow was actually in a tremble of hope or impatience;—­and, not content with listening, he peered every few minutes down the well of the staircase, and when he was not doing that, tramped from end to end of the narrow passage-way separating the head of the stairs from the door he had pointed out, like one to whom minutes were hours.  All this time he seemed to forget George who certainly had as much reason as himself for finding the time long.  But when, after some half hour of this tedium and suspense, there rose from below the faint clatter of ascending footsteps, he remembered his meek companion and beckoning him to one side, began a studied conversation with him, showing him a note-book in which he had written such phrases as these: 

Don’t look up till he is fairly in range with the light.

There’s nothing to fear; he doesn’t know either of us.

If it is a face you have seen before;—­if it is the one we are expecting to see, pull your necktie straight.  It’s a little on one side.

These rather startling injunctions were read by George, with no very perceptible diminution of the uneasiness which it was only natural for him to feel at the oddity of his position.  But only the demand last made produced any impression on him.  The man they were waiting for was no further up than the second floor, but instinctively George’s hand had flown to his necktie, and he was only stopped from its premature re-arrangement by a warning look from Sweetwater.