Horatia. Why, Sir, I always thought them a sort of stone.... A study of the development of the helicopter principle was published in France in 1868, when the great French engineer Paucton produced his Th茅orie de la Vis d鈥橝rchim茅de. For some inexplicable reason, Paucton was not satisfied with the term 鈥榟elicopter,鈥?but preferred to call it a 鈥榩t茅rophore,鈥?a name which, so far as can be ascertained, has not been adopted by any other writer or investigator. Paucton stated that, since a man is capable of sufficient force to overcome the weight of his own body, it is only necessary to give him a machine which acts on the air 鈥榳ith all the force of which it is capable and at its utmost speed,鈥?and he will then be able to lift himself in the air, just as by the exertion of all his strength he is able to lift himself in water. 鈥業t would seem,鈥?says Paucton, 鈥榯hat in the pt茅rophore, attached vertically to a carriage, the whole built lightly and carefully assembled, he has found something that will give him this result in all perfection. In construction, one would be careful that the machine40 produced the least friction possible, and naturally it ought to produce little, as it would not be at all complicated. The new D?dalus, sitting comfortably in his carriage, would by means of a crank give to the pt茅rophore a suitable circular (or revolving) speed. This single pt茅rophore would lift him vertically, but in order to move horizontally he should be supplied with a tail in the shape of another pt茅rophore. When he wished to stop for a little time, valves fixed firmly across the end of the space between the blades would automatically close the openings through which the air flows, and change the pt茅rophore into an unbroken surface which would resist the flow of air and retard the fall of the machine to a considerable degree.鈥? Charles. No, Miss, I tried to serve myself. My poor boy! "Go to the office again to-night?" exclaimed his mother and his wife simultaneously. Later experiments proved that the biplane type of glider gave better results than the rather cumbrous model consisting of five tiers of planes. Longer and more numerous glides, to the number of seven to eight hundred, were obtained, the rate of descent being112 about one in six. The longest distance traversed was about 120 yards, but Chanute had dreams of starting from a hill about 200 feet high, which would have given him gliding flights of 1,200 feet. He remarked that 鈥業n consequence of the speed gained by running, the initial stage of the flight is nearly horizontal, and it is thrilling to see the operator pass from thirty to forty feet overhead, steering his machine, undulating his course, and struggling with the wind-gusts which whistle through the guy wires. The automatic mechanism restores the angle of advance when compromised by variations of the breeze; but when these come from one side and tilt the apparatus, the weight has to be shifted to right the machine ... these gusts sometimes raise the machine from ten to twenty feet vertically, and sometimes they strike the apparatus from above, causing it to descend suddenly. When sailing near the ground, these vicissitudes can be counteracted by movements of the body from three to four inches; but this has to be done instantly, for neither wings nor gravity will wait on meditation. At a height of three hundred or four hundred feet the regulating mechanism would probably take care of these wind-gusts, as it does, in fact, for their minor variations. The speed of the machine is generally about seventeen miles an hour over the ground, and from twenty-two to thirty miles an hour relative to the air. Constant effort was directed to keep down the velocity, which was at times fifty-two miles an hour. This is the purpose of the starting and gliding against the wind, which thus furnishes an initial velocity without there being undue speed at the landing. The highest wind we dared to experiment in blew at thirty-one miles an hour; when the113 wind was stronger, we waited and watched the birds.鈥? Obviously not. Better rates? Nope. More services? No. 一本道在线高清无视码v视频日本*欧美A片*亚州最好看的色情不卡电影 All this, however, is hypothetical. Remains the airship of to-day, developed far beyond the promise of five years ago, capable, as has been proved by its achievements both in Britain and in Germany, of undertaking practically any given voyage with success. The history of the years 1899 to 1903 in the Langley series of experiments contains a multitude of detail far beyond the scope of this present study, and of interest mainly to the designer. There were frames, engines, and propellers, to be considered, worked out, and constructed. We are concerned here mainly with the completed machine and its trials. Of these latter it must be remarked that the only two actual field trials which took place resulted in accidents due to the failure140 of the launching apparatus, and not due to any inherent defect in the machine. It was intended that these two trials should be the first of a series, but the unfortunate accidents, and the fact that no further funds were forthcoming for continuance of experiments, prevented Langley鈥檚 success, which, had he been free to go through as he intended with his work, would have been certain. I am feeling better because I am so glad, Isola answered naively, putting her hand into Allegra's. The French Air Force at the beginning of the War consisted of upwards of 600 machines. These, unlike the Germans, were not standardised, but were of many and diverse types. In order to get replacements quickly enough, the factories had to work on the designs they had, and thus for a long time after the outbreak of hostilities standardisation was an impossibility. The versatility of a Latin race in a measure compensated for this; from the outset, the Germans tried to overwhelm the French Air Force, but failed, since they had not the numerical superiority, nor鈥攖his equally a determining factor鈥攖he versatility and resource of the French pilots. They calculated on a 50 per cent superiority to ensure success; they needed more nearly 400 per cent, for the German fought to rule, avoiding risks whenever possible, and definitely instructed to save both machines and pilots wherever possible. French pilots, on the other hand, ran all the risks there were, got news of German movements, bombed the enemy, and rapidly worked up a very respectable anti-aircraft force which, whatever it may have accomplished in the way of hitting German planes, got on the German pilots鈥?nerves.