XVI LONDON TO MANCHESTER It would appear that the rotary type of engine is capable of but little more improvement鈥攕ave for such devices as these of the last two engines mentioned, there is little that Laurent Seguin has not already done in the Gnome type. The limitation of the rotary lies in its high fuel and lubricating oil consumption, which renders it unsuited for long-distance aero work; it was, in the war period, an admirable engine for such short runs as might be involved in patrol work 鈥榦ver the lines,鈥?and for similar purposes, but the water-cooled Vee or even vertical, with its much lower fuel consumption, was and is to be preferred for distance work. The rotary air-cooled type has its uses, and for them it will probably remain among the range of current types for some time to come. Experience of matters aeronautical is sufficient to show, however, that prophecy in any direction is most unsafe. As a result of this laboratory research work the third Wright glider, which was taken to Kill Devil Hill in September, 1902, was far more efficient aerodynamically than either of its two predecessors, and was fitted with a fixed vertical fin at the rear in addition to the movable elevator in front. According to Mr Griffith Brewer,8 this third glider contained 305 square feet of surface; though there may possibly be a mistake here, as he states9 the surface of the previous year鈥檚 glider to have been only 290 square feet, whereas Wilbur Wright himself10 states it to have been 308 square feet. The matter is not, perhaps, save historically, of much importance, except that the gliders are believed to have been progressively larger, and therefore if we accept Wilbur Wright鈥檚 own figure of the surface of the second glider, the third must have had a greater area than that given by Mr Griffith Brewer. Unfortunately, no evidence of the Wright Brothers themselves on this point is available. 2018最新福利天堂视频 On the fifth of June, 1783, the Montgolfiers鈥?hot-air balloon rose at Versailles, and in its rising divided the study of the conquest of the air into two definite parts, the one being concerned with the propulsion of gas lifted, lighter-than-air vehicles, and the other being crystallised in one sentence by Sir George Cayley: 鈥楾he whole problem,鈥?he stated, 鈥榠s confined within these limits, viz.: to make a surface support a given weight by the application of power to the resistance of the air.鈥?For about ten years the balloon held the field entirely, being regarded as the only solution of the problem of flight that man could ever compass. So definite for a time was this view on the eastern side of the Channel that for some years practically all the progress that was made in the development of power-driven planes was made in Britain.