“Nothing to it at all, Buddy,” he advised, putting his hand on one of the little iron plates that studded the doorway in two rows from jamb to hinges. “The hollow is behind this one. See?” Henri illustrated by thumb pressure on the edge of the metal disc, which turned upward, exposing to view a steel ring slightly more than finger size.
Without waiting for further demonstration, Billy promptly tried a pull on the hoop in the hole. It was lost motion, for the ring had no forward give to it. An experimental push, also, was without result.
“Turn it,” was Henri’s rather impatient suggestion.
That was the trick that drew the bolt. The boys heard the click of the hidden spring, and so sudden was the giving of the barrier that Billy, using an arm prop against it, went in like a diver. The recoil was equally speedy, and Henri saved himself a shutout by using his foot as a preventing wedge.
With both boys inside, the postern closed behind them without a sound. The passage here was so narrow that it enforced single file proceedings. At the right was the wall of the silversmith’s shop, to the left the barred windows of the warehouse. The structures might have been houses of the dead for all the signs of occupancy then shown.
Billy was uncertain in his mind as to the first tackle of the mystery that he had conjured to while away an idle hour. He was not particularly anxious to run afoul of Ricker and his hairy retainer. Indeed, had he glimpsed the heads of either of them in window or doorway it would have been back to the square for him, and if there was any talking to be done, that conversation would have to be exchanged in the open.
But it was just that bump of curiosity, of which Henri had more than once jokingly said “could only be reduced by a smash with a sandbag.”
Billy’s conclusion favored further exploration of the vaulted walk, which no doubt had been originally designed simply as an air shaft, and later converted to some other use. It was the latter supposition that appealed to the would-be explorer.
With continued progress between the walls, the boys marked gradual descent, becoming more pronounced at every step. Then the path curved abruptly and ended at the base of a tower-like brick chimney, built outside of the warehouse wall and making the first opening in the hitherto overlapping cornices of the buildings running parallel.
“The silversmith’s shop is considerable of a bluff when you come to compare the known front with the unknown rear,” remarked Billy, who had been mentally figuring the distance from street to postern, and from postern to this chimney obstruction.