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时间: 2019年12月14日 18:37

� In the dining-room, ma'am. � � Oh yes; I believe Minnie asked her there at first to please Algernon. Minnie can be good-natured in that sort of way. But I don't know that it was very judicious. 鈥淭hey get the job done.鈥? 亚洲在线大香蕉网久久 久久综合伊人,伊人大香蕉久久网 169 They came up against the problem to which Riach has since devoted so much attention, that of propeller design. 鈥榃e had thought of getting the theory of the screw-propeller from the marine engineers, and then, by applying our table of air-pressures to their formul?, of designing air-propellers suitable for our uses. But, so far as we could learn, the marine engineers possessed only empirical formul?, and the exact action of the screw propeller, after a century of use, was still very obscure. As we were not in a position to undertake a long series of practical experiments to discover a propeller suitable for our machine, it seemed necessary to obtain such a thorough understanding of the theory of its reactions as would enable us to design them from calculation alone. What at first seemed a simple problem became more complex the longer we studied it. With the machine moving forward, the air flying backward, the propellers turning sidewise, and nothing standing still, it seemed impossible to find a starting point from which to trace the various simultaneous reactions. Contemplation of it was confusing. After long arguments we often found ourselves in the ludicrous position of each having been converted to the other鈥檚 side, with no more agreement than when the discussion began. That may be, sir. Still, of course, it is no light matter to steal a letter. And as to the means of tracing it, why I have heard of trap-letters being sent, containing marked money. In the matter of illustrations, it has been found very difficult to secure suitable material. Even the official series of photographs of aeroplanes in the war period is curiously incomplete, and the methods of censorship during that period prevented any complete series being privately collected. Omissions in this respect will probably be remedied in future editions of the work, as fresh material is constantly being located. But only if she could handle the heat. The temperature was nearing 100 degrees just as Jenn wasentering the furnace鈥攖he jagged up-and-down climb to the Los Alisos settlement. The trailhugged a sheer rock wall that plunged and soared and plunged again, gaining and losing somethree thousand feet. Any of the hills in the Los Alisos stretch would rank among the hardest Jennhad ever seen, and there were at least half a dozen of them, strung one behind the other. The heatshimmering off the rocks felt as if it was blistering her skin, but she had to stick tight to the canyonwall to avoid slipping off the edge and into the gorge below. And I have watched from the first blush of morn,