"We'll get the building detective, anyway," insisted the manager. "Let him come along, but do not let him know until we are sure. If we are right we will find a most unusual infernal machine," said Linane. * * * * * The three men entered the suite with a pass-key. The detective was left outside in the hall to halt anyone who might disturb the searchers. It was as Jenks had thought. In an inner room they found a diabolical machine--a single string stretched across two bridges, one of brass and one of wood. A big horsehair bow attached to a shaft operated by a motor was automatically sawing across the string. The note resulting was evidently higher than the range of the human ear, because no audible sound resulted. It was later estimated that the destructive note was several octaves higher than the highest note on a piano. The entire machine was enclosed in a heavy wire-net cage, securely bolted to the floor. Neither the string or bow could be reached. It was evidently the Mad Musician's idea that the devilish contrivance should not be reached by hands other than his own. How long the infernal machine had been operating no one knew, but the visitors were startled when the building suddenly began to sway perceptibly. Jenks jumped forward to stop the machine but could not find a switch. "See if the machine plugs in anywhere in a wall socket!" he shouted to Linane, who promptly began examining the walls. Jenks shouted to the building manager to phone the police to clear the streets around the big building. "Tell the police that the Acme Theater building may crash at any moment," he instructed. The engineers were perfectly cool in face of the great peril, but the building manager lost his head completely and began to run around in circles muttering: "Oh, my God, save me!" and other words of supplication that blended into an incoherent babel. Jenks rushed to the man, trying to still his wild hysteria. The building continued to sway dangerously. * * * * * Jenks looked from a window. An enormous crowd was collecting, watching the big building swinging a foot out of plumb like a giant pendulum. The crowd was growing. Should the building fall the loss of life would be appalling. It was mid-morning. The interior of the building teemed with thousands of workers, for all floors above the third were offices. Teddy Jenks turned suddenly. He heard the watchman in the hall scream in terror. Then he heard a body fall. He rushed to the door to see the Mad Musician standing over the prostrate form of the detective, a devilish grin on his distorted countenance.