“Good morning, Gilbert,” Nick greeted him familiarly. “I want to visit your roof once more.”

“Certainly, Nick, as many times as you wish. Go ahead. You know the way.”

Nick already was on his way to the rear room, where he quickly mounted the ladder and opened the scuttle leading to the roof. One after another the three detectives climbed out.

It presented in the bright morning sunlight a much different appearance from that of the night before. There was much less danger of a slip and a fall to the pavements far below. Nick at once approached the rear edge of it, at a point directly over the window of the[Pg 18] bedroom in the Strickland flat. Some of the gravel near the edge had been brushed away. Crouching to gaze over, Nick made a discovery that immediately confirmed his increasing suspicions.

In the upper surface of the timber forming the edge of the roof were four holes, somewhat less than a foot apart, and which evidently had been recently made with four large screws.

“Here we have it,” Nick cried, when Chick and Patsy approached. “There has been a rigging of some kind screwed to this timber.”

“Gee! that’s as plain as twice two, chief,” said Patsy.

“Notice that it is directly in line with the chimney, which is less than eight feet from the edge of the roof. If I am not mistaken—no, I am right,” Nick broke off; then added confidently, rising to inspect the chimney. “Here are splinters of wood on some of the bricks, also particles evidently rubbed from a rope. Here in the gravel beyond the chimney, too, are indications that the end of a piece of joist rested.”

“You think, then——”

“The evidence speaks for itself,” Nick interposed. “A long piece of joist made fast to the chimney was run out over an ordinary sawhorse, I judge, which was fastened to a strip of board securely strewed to the edge of the roof. A rope from the outer end of the joist, or a rigging of some kind, enabled one of the crooks to descend to the windows of the Strickland flat.”