A flush mounted to Bob's forehead. He was quite sure his shoes were immaculately polished. He also realized perfectly that he ought not notice the audience, but remain rigidly at attention. But presently curiosity got the better of discipline. He shot a furtive glance at his feet--a glance that flashed sidewise beyond the trim shoes and well-fitting leggings to rest in dumb, horrified amazement on the crack extending below the double doors, through which a thin line of smoke was slowly trickling. CHAPTER XXXI THE RIOT WEDGE For a long moment Bob Gibson stood like one petrified. He thought of the crowd, of the narrow, twisted stairs, of panic. What ought he do? What was there possible for him to do? He tried to remember what the scout book said about fires and panics, but his brain seemed numb. Before it had cleared there came a choking cry from the other side, and Bennie Rhead, the youngest scout in the troop, slipped out of the line, and before any one could stop him, had jerked open the door to let in a rolling cloud of dense black smoke. Like a flash Wesley Becker leaped after him, dragged him back, and slammed the door; but the damage was done. There was a long, gasping, concerted sigh, as of hundreds of people catching their breath in unison; in a second more the hall resounded with that cry which chills the blood and sends shivers chasing down the spine. To Gibson, standing pale and frightened, it seemed as if that whole close-packed assemblage surged up like some awful monster and rushed toward him, a bedlam of shrill sound; while out of doors the wild clamor of the fire-alarm suddenly burst forth to add horror to the scene. Shaking and terrified, Bob nevertheless stood motionless, partly because he did not know what else to do, but mainly because the fellows on either side of him had not stirred. He dug his teeth into his under lip to keep back a frightened whimper, and then of a sudden the clear, high voice of Mr. Curtis rang out above the deafening din and turmoil: "Troop Five prepare to form double riot wedge! One!" Instinctively Bob leaped two paces forward and a little to the right. In like fashion the others darted to their positions with the swift precision of machines. Not a scout failed. Even Bennie Rhead, frightened as he was, made no mistake, and in a trice the wedge was complete. "Two!" shouted the scoutmaster. Down swung the staves, interlocking in a double barrier of stout hickory backed by equally sturdy muscle. The scoutmaster had barely time to place himself at the apex of the wedge before the mob struck it. "Hold fast, boys!" he cried. "Brace your feet and don't let them break the line!" He flung up both arms in the faces of the maddened throng. "Stop!" he shouted. "You can't get out this way. The stairs are impassable. Stop crowding! There's no danger if you keep your heads. The fire-escapes are in good order. The windows--"