鈥業 will, first of all, presuppose that air has weight owing to the vapours and halations which ascend from the earth and seas to a height of many miles and surround the whole of our terraqueous globe; and this fact will not be denied by philosophers, even by those who may have but a superficial knowledge, because it can be29 proven by exhausting, if not all, at any rate the greater part of, the air contained in a glass vessel, which, if weighed before and after the air has been exhausted, will be found materially reduced in weight. Then I found out how much the air weighed in itself in the following manner. I procured a large vessel of glass, whose neck could be closed or opened by means of a tap, and holding it open I warmed it over a fire, so that the air inside it becoming rarified, the major part was forced out; then quickly shutting the tap to prevent the re-entry I weighed it; which done, I plunged its neck in water, resting the whole of the vessel on the surface of the water, then on opening the tap the water rose in the vessel and filled the greater part of it. I lifted the neck out of the water, released the water contained in the vessel, and measured and weighed its quantity and density, by which I inferred that a certain quantity of air had come out of the vessel equal in bulk to the quantity of water which had entered to refill the portion abandoned by the air. I again weighed the vessel, after I had first of all well dried it free of all moisture, and found it weighed one ounce more whilst it was full of air than when it was exhausted of the greater part, so that what it weighed more was a quantity of air equal in volume to the water which took its place. The water weighed 640 ounces, so I concluded that the weight of air compared with that of water was 1 to 640鈥攖hat is to say, as the water which filled the vessel weighed 640 ounces, so the air which filled the same vessel weighed one ounce.鈥? The Napier Company specialised on one type of engine from the outset, a power plant which became known as the 鈥楲ion鈥?engine, giving 450 horse-power with twelve cylinders arranged in three rows of four each. Considering the engine as 鈥榙ry,鈥?or without fuel and accessories, an abnormally light weight per horse-power鈥攐nly 1鈥?9 lbs.鈥攚as attained when running at the normal rate of revolution. The cylinders and water-jackets are of steel, and there is fitted a detachable aluminium cylinder head containing inlet and exhaust valves and valve actuating mechanism; pistons are of aluminium alloy, and there are two inlet and two exhaust valves to each cylinder, the whole of the valve mechanism being enclosed in an oil-tight aluminium case. Connecting rods and crankshaft are of steel, the latter being machined from a solid steel forging and carried in five roller bearings and one plain bearing at the forward end. The front end of the crank-case encloses reduction gear for the propeller shaft, together with the shaft and bearings. There are two suction and one pressure type oil pumps driven through gears at half-engine speed, and two 12 spark magnetos, giving 2 sparks in each cylinder. Well, don't distress yourself about it, Gibbs. I have full reliance on you in every way. CHAPTER II. Who is that fellow who has just gone out? he asked of Gibbs, entering the office by the public door instead of his own private one, in order to put the question. In summing up the results of his journey to town, he was satisfied. Things were certainly not so pleasant as they might be. But were they not better, on the whole, than when he had left Whitford? He decidedly thought they were; which did not, of course, diminish his sense of being a victim to circumstances and the Seely family. Anyway he had broken with Whitford. My lord must get him out of that baraque! The very thought of leaving the place raised his spirits. And, as he had the coach to himself during nearly all the journey, he was able to stretch his legs and make himself comfortable; and he awoke from a sound and refreshing sleep as the mail-coach rattled into the High Street and rumbled under the archway of the "Blue Bell." 电影日本强奷在线播放 Oh! I'm very glad. The British Military Aeroplane Competition held in the summer of 1912 had done much to show the requirements in design by giving possibly the first opportunity for a definite comparison of the performance of different machines as measured by impartial observers on standard lines鈥攁lbeit the methods of measuring were crude. These showed that a high speed鈥攆or those days鈥攐f 75 miles an hour or so was attended by disadvantages in the form of an equally fast low speed, of 50 miles per hour or more, and generally may297 be said to have given designers an idea what to aim for and in what direction improvements were required. In fact, the most noticeable point perhaps of the machines of this time was the marked manner in which a machine that was good in one respect would be found to be wanting in others. It had not yet been possible to combine several desirable attributes in one machine. The nearest approach to this was perhaps to be found in the much discussed Government B.E.2 machine, which was produced from the Royal Aircraft Factory at Farnborough, in the summer of 1912. Though considerably criticised from many points of view it was perhaps the nearest approach to a machine of all-round efficiency that had up to that date appeared. The climbing rate, which subsequently proved so important for military purposes, was still low, seldom, if ever, exceeding 400 feet per minute; while gliding angles (ratio of descent to forward travel over the ground with engine stopped) little exceeded 1 in 8. 鈥楨ver, my dear Sir, Cayley was a man in advance of his time, in many ways. Of independent means, he made the grand tour which was considered necessary to the education of every young man of position, and during this excursion he was more engaged in studies of a semi-scientific character than in the pursuits that normally filled such a period. His various writings prove that throughout his life aeronautics was the foremost subject in his mind; the Mechanic鈥檚 Magazine, Nicholson鈥檚 Journal, the Philosophical Magazine, and other periodicals of like nature bear witness to Cayley鈥檚 continued research into the subject of flight. He approached the subject after the manner of the trained scientist, analysing the mechanical properties of air under chemical and physical action. Then he set to work to ascertain the power necessary for aerial flight, and was one of the first to enunciate the fallacy of the hopes of successful flight by means of the steam engine of those days, owing to the fact that it was impossible to obtain a given power with a given weight.