"He had put up the back-door game on you," said the reporter. "Yes, sir; just what I said to Conklin. So, quick as a wink, I sent him around the block to keep his eye peeled on the next street and I waited here. And here I've been ever since. If Conklin isn't on the block above, it must be because Chatham has made tracks again, and he after him." "I'll go and find out," said Sturgis. "Has any one else called at the Manhattan Chemical Company's office since you have been on watch?" "No, sir; but a couple of hours ago an express wagon came along and delivered a long wooden box; might have been chemicals for the wholesale department, for it was lowered to the cellar by the hoist in the areaway. The blond young man receipted for the box." "Very well, Shrady. Hang on a little while longer, and I shall have you relieved just as soon as I possibly can." So saying, the reporter, who had been pretending to look through his pockets for a coin, ostentatiously slipped a nickel into the outstretched palm before him. The light seemed to die out of the sharp eyes of the detective, and it was the miserable drunkard who staggered back to his place on the stoop next to the saloon, unmindful of the gibes of the young rowdies congregated there. Sturgis walked up to the next street, where he found a second detective on duty. "Anything new, Conklin?" he asked. "No, sir; he's been lying low; looks like he knew he was spotted this time." "Good. Stay here until I can notify the police that we have run down the quarry. It will be necessary to obtain a search warrant for the Manhattan Chemical Company's place. In the meantime, if Chatham should attempt to make tracks, hang on to him like his shadow and send back word here as soon as you can." "All right, sir." Sturgis, after leaving Conklin, walked along the street which the detective was watching and carefully inspected every house on the block. Almost all were huge office buildings; but here and there an old-fashioned brown-stone front stood out conspicuously against the broad expanse of brick walls and iron columns. Half way down the street one of these old houses stood well back from the street line behind a small garden. The reporter stopped near this and read the numbers on the adjoining buildings. "This is directly back of the Manhattan Chemical Company's office," he mused. "I wonder who lives here. It looks like a respectable place enough. One could obtain a good view of the rear of the Manhattan Chemical Company's office from the back windows. H'm----" He stood thoughtfully considering what pretext he could use to gain admission to the house, when suddenly he became aware of the presence of a man who had approached with noiseless steps. "Ah, is that you, Mr. Sturgis?" said the calm, sardonical voice of Doctor Murdock. The reporter started inwardly but gave no outward sign of surprise. "Were you about to do me the honor of calling?" continued the chemist.