"That is the world’s supply at present, excluding the two cylinders which are already fitted on the machine." "The world’s supply," ejaculated Carl, who was thinking of the huge petrol tank, which in a Fokker scout would last only three hours with the throttle wide open. "That won’t last long, unless the pressure is enormous." "The pressure is enormous, my friend; so enormous that if anything happened it would----" "Blow a hole in the universe, I reckon," interposed Max. "You are right, and that is the only danger connected with the _Scorpion_. The other danger you mentioned, that of fire, is altogether eliminated. There would be nothing to burn if one of these cylinders exploded, for there would be nothing left--in the vicinity." "_Sacre bleu_!" exclaimed Carl, _sotto voce_, for, brave youth that he was, he shuddered at the thought. Max was the more practical of the two, however, for he belonged not to the highly sensitive scouts, but to the heavy bombers, and he merely asked to satisfy his curiosity:-- "How far will one of those cylinders take us, Rittmeister?" "Ten thousand miles," replied the chief, "that is, one fitted to either engine." "Good! Let me see, there are ten here, and one already fitted to either motor makes a dozen. Why, they would carry us"--and here he made a rapid calculation--"they would take us twice round the world." "Precisely, and with a little to spare, when we had completed the double trip." "And what speed would she pick up, say at a level flight?" For answer the chief looked at the professor, as though uncertain whether to reply to this question. "They have taken the oath, sir," he pleaded, "They cannot withdraw," and the great scientist nodded his acquiescence. "Two hundred and fifty miles without being pushed," he replied at length. "Donnerwetter! And what if she were pushed?" "I cannot say, she has never been driven beyond that." "What a deuce of a noise she will make--like a whole formation of Gothas, I should imagine," said Max. The professor smiled, but left it to the Rittmeister to explain this last point. "The engines are silent, but there is a slight hum from the propellers. That cannot be effaced at present, but it is nothing." Then, having given all these details, the visitors made a closer inspection of the machine. They were permitted to climb into the conning-tower, to handle the controls, and the two swivel machine guns mounted there. They were shown into the little cabin, where four men might sit at the little table, or lie down at full length, but could not stand upright. The steel struts, steel folding wings, the carefully packed spares, the little mica windows in the cabin--these, and a dozen other things, were pointed out and explained to them--the stores which were already packed, comprising chronometrical instruments, maps, charts, ammunition for the guns, compressed food, etc., until their bewilderment grew, and their astonishment became unbounded.