But they had learned that one of the tenants in the house, at a late hour in the previous night, had seen two men enter Spike Thomas’ rooms, supposing one of them to be Spike Thomas. As neither Spike Thomas nor Bally Morris had been near the rooms during the night, the conclusion was that somebody had entered for the purpose of stealing those drawings and models, and had obtained them. That was the whole story, although it was garnished with oaths and guesses and charges. Patsy at once formed an idea as to who those thieves were, but he made no remark to Bally Morris or Spike. Sending them away, with instructions to hold themselves in readiness to obey any call that he might make on them, he hurriedly finished his dressing and went to the room of Chick, who had quarters in the same house. Rapping on Chick’s door, he received, however, no response. The door was locked, and, as Chick was a light sleeper, Patsy felt that Chick was not within his room. In his own room there was a key to Chick’s, as there was in Chick’s a key to his, that each might enter the other’s room when necessity required. Obtaining that key and entering the room, Patsy saw at a glance that Chick had not occupied it during the night. “Holy smoke!” he said aloud, to himself, “I don’t like the looks of this. I must tell the chief.” Dashing downstairs into the street, Patsy went to a drug store where there was a telephone that he frequently used, and obtained communication with Nick at his home. Telling his chief what had occurred, the third theft of the papers, he also said that Chick had not returned to his room during the night. “Chief,” said Patsy, over the wire, “I’m going to try and pick up track of Chick.” “Where?” asked Nick. “I shall strike Rivington and the Bowery first, then Thirty-fourth Street, and then Forty-second Street.” “Right,” replied Nick. “Stay about the Bowery and Rivington until I get over there. I shall come over at once.” Patsy hurried over to the Bowery, and sought the corner of Rivington Street, where the first thing that attracted his attention was a red chalk mark on the pavement. Many feet had passed over the mark since it had been made, and it required close observation to discover its meaning. Finally, Patsy determined that it had been made the evening before, and that it was a notice to himself and the chief that Chick was on the shadow, and going up the Bowery. He crossed to the upper side of the street, and there found another mark, so dim, however, that he could not tell what its meaning was, but the indication seemed to be still pointing up the Bowery. He went to the next corner, and there found another mark. This was plainer, and still indicated that Chick was going up the Bowery. “These are last night’s marks,” said Patsy to himself. “If he has kept it up all night, we must get to him in time.”