Again the professor turned to the keys, and sent his last instructions through the ether waves to his confederate, the brigand of the eastern skies. *CHAPTER XX* *"HANDS UP!"* "Haende in die hohe!" cried Keane as soon as the last message had been sent. "Der Teufel!" gasped the professor as two swift shadows darted out from behind the curtain, and the two men whom he had just been discussing with such utter contempt confronted him and his accomplice with gleaming pistols. "Hands up!" repeated Keane, anxious to give the professor another chance. With a blasphemous oath the man of evil genius, who saw that he had been outwitted, reached for a small hand grenade which lay beside him on the table, and shouted:-- "Never!" "Then take that!" cried the Englishman, and two puffs of greenish smoke, following a sharp crackle, burst simultaneously from the pistols, for they had both fired together. The new Asphixor bullets took immediate effect. Both the Germans staggered, clutched their throats as though to ward off the effects of this new powerful gas recently discovered and adapted by that eminent British scientist, Sir Joseph Verne--then lurched and fell, whilst their opponents stepped back and quickly fitted on their safety masks. "They are both sound asleep," observed Keane, when, the fumes having cleared away, he threw aside his respirator and carefully examined the unconscious men. "Let them sleep," said Sharpe, who would have adopted even more drastic measures if he could have had his own way. "’Tis scant mercy they would have shown to us if we had been in their power." "And now let us get to work, for they will awaken in seven or eight hours, and we have much to do. We must prepare for Colonel Tempest, and also for this raider," urged Keane. "But they will not come to-day, Captain." "Scarcely, but we must be prepared for anything. There are only a couple of us." "Shall we secure these men, in case they awake earlier than the stipulated time?" "No, let us remove their slumbering forms behind the curtain there; we will attend to them before they awake. I do not like the idea of strapping down unconscious men, even though they are criminals. We will watch them from time to time." Then for the next half-hour they carried out a careful examination of the hangar and its contents. They were amazed at the intricate and wonderful mechanism with which the place was fitted. It seemed impossible that these things could have been transported hither without attracting attention. Parts of aeroplane wings, struts, propellers, engine-fittings, strange, weird-looking cylinders, retorts, analytical appliances, instruments and vessels for chemical research, powerful but silent dynamos, and numberless other things, all neatly arranged, and apparently in working order, half filled the place.