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ENGLISH 京香番号和剧情简介The doctor now became more communicative on other matters. According to him the Germans contended that the inhabitants had been shooting from windows and cellars, in order to prevent the120 garrison from assisting their comrades, who were fighting a battle against the Belgians at a distance of about four miles and a half from the town. Such an organised action of the inhabitants, under the tyrannical rule of the Germans during the eight days before the destruction, he called impossible, and therefore the whole accusation absurd. At any rate they had felt that the destruction was coming, and had been planned systematically, for during those eight days the Germans had plundered the population, and taken from them all bread, even what they required to feed themselves.The combination of several functions in one machine, although it may not seem an important matter to be considered here, is nevertheless one that has much to do with the manufacture of machines, and constitutes what may be termed a principle of construction.
"All right; you may go!"I had to walk along the very edge of the unstable bridge in order to avoid the wheels of the passing carriages, which shook the whole bridge and made the rather loose boards clatter. In the meantime, at no considerable distance, some shells fell in the Meuse, fired at the bridge from Fort Pontisse. Yet, I did not mind it at all, as all these new experiences stunned me, so to speak; the incessant hellish noises of the batteries, the burning houses, the smoke swooping down, the excited soldiers....The sudden and varied resistance to line shafts tends to loosen couplings, destroy gearing, and produce sudden strains that are unknown in other cases; and shafting arranged with the usual proportions for transmitting power will soon fail if applied to driving trip-hammers. Rigid connections or metal attachments ace impracticable, and a slipping belt arranged so as to have the tension varied at will is the usual and almost the only successful means of transmitting power to hammers. The motion of trip-hammers is a curious problem; a head and die weighing, together with the irons for attaching them, one hundred pounds, will, with a helve eight feet long, strike from two to three hundred blows a minute. This speed exceeds anything that could be attained by a direct reciprocal motion given to the hammer-head by a crank, and far exceeds any rate of speed that would be assumed from theoretical inference. The hammer-helve being of wood, is elastic, and acts like a vibrating spring, its vibrations keeping in unison with the speed of the tripping points. The whole machine, in fact, must be constructed upon a principle of elasticity throughout, and in this regard stands as an exception to almost every other known machine. The framing for supporting the trunnions, which one without experience would suppose should be very rigid and solid, is found to answer best when composed of timber, and still better when this timber is laid up in a manner that allows the structure to spring and  yield. Starting at the dies, and following back through the details of a trip-hammer to the driving power, the apprentice may note how many parts contribute to this principle of elasticity: Firstthe wooden helve, both in front of and behind the trunnion; nextthe trunnion bar, which is usually a flat section mounted on pivot points; thirdthe elasticity of the framing called the 'husk,' and finally the frictional belt. This will convey an idea of the elasticity required in connecting the hammer-head with the driving power, a matter to be borne in mind, as it will be again referred to.
A solid milling cutter must be an accurately finished piece of work, made with more precision than can be expected in the work it is to perform. This accuracy cannot be attained by ordinary processes, because such tools, when tempered, are liable to become distorted in shape, and frequently break. When hardened they must be finished by grinding processes, if intended for any accurate work; in fact, no tools, except gauging implements, involve more expense to prepare, and none are so liable to accident when in use.I pitied him from the bottom of my heart, and tried to console him by remarking that it was all a misunderstanding, and that I would see to it that he would soon be released.
In front of me, behind me, on all sides, the guns boomed, clouds of dust and smoke filled the air, making it impossible to see much, which made the awe and terror endurable; but after the air became clear again, and the sun shed glowing light on the beautiful fields, it was terrible to think that all those dots in the plain were the bodies of young men, cruelly crushed by the infernal products of human ingenuity. It was agony to see here and there a body rising up, merely to fall down again immediately, or an arm waving as if invoking help.
An old smith who has stood at the forge for a score of years will take the same interest in tempering processes that a novice will. When a piece is to be tempered which is liable to spring or break, and the risk is great, he will enter upon it with the same zeal and interest that he would have done when learning his trade.3. The valve must move after the hammer stops.It is not intended to claim that this platen-reversing motion cannot, like any other mechanical movement, be resolved mathematically, but that the mechanical conditions are so obscure and the invention made at a time that warrants the supposition of accidental discovery.
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The prevailing custom of casting machine frames in one piece, or in as few pieces as possible, leads to a great deal of bar-boring, most of which can be performed accurately enough by boring bars supported in and fed through bearings. By setting up temporary bearings to support boring-bars, and improvising means of driving and feeding, most of the boring on machine frames can be performed on floors or sole plates and independent of boring machines and lathes. There are but few cases in which the importance of studying the principles of tool action is more clearly demonstrated than in this matter of boring; even long practical experience seldom leads to a thorough understanding of the  various problems which it involves.The most perfect castings for gear wheels and pulleys and other pieces which can be so moulded, are made by drawing the patterns through templates without rapping. These templates are simply plates of metal perforated so that the pattern can be forced through them by screws or levers, leaving the sand intact. Such templates are expensive to begin with, because of the accurate fitting that is required, especially around the teeth of wheels, and the mechanism that is required in drawing the patterns, but when a large number of pieces are to be made from one pattern, such as gear wheels and pulleys, the saving of labour will soon pay for the templates and machinery required, to say nothing of the saving of metal, which often amounts to ten per cent., and the increased value of the castings because of their accuracy.Power-hammers operated by crank motion, adapted to the lighter kinds of work, are now commonly met with in the forging-shops of engineering establishments. They are usually of very simple construction, and I will mention only two points in regard to such hammers, which might be overlooked by an apprentice in examining them.
For quite a quarter of an hour they seemed to proceed successfully, as obviously not one shell exploded in their neighbourhood. But suddenly all along their line dark masses several yards high rose up. This was the effect of numerous exceedingly well-aimed shells on the dry, loose sand. Soon the men were surrounded by those thick clouds of dust, and only during the first few minutes I saw here and there one of those shades in human form tumble down, evidently hit by one of the projectiles. Then I saw nothing for a long while, excepting the thick wall of dust, which seemed to remain standing up, for constantly the shells threw up anew the earth that had only just fallen down.In casting and forging operations the material is treated while in a heated and expanded condition; the nature of these operations is such that accurate dimensions cannot be attained, so that both forgings and castings require to be made enough larger than their finished dimensions to allow for shrinkage and irregularities. Finishing as a process consists in cutting away this surplus material, and giving accurate dimensions to the parts of machinery when the material is at its natural temperature. Finishing operations being performed as said upon material at its normal temperature permits handling, gauging and fitting together of the parts of machinery, and as nearly all other processes involve heating, finishing may be called the cold processes of metal work. The operations of a fitting shop consist almost entirely of cutting, and grinding or abrading; a proposition that may seem novel, yet these operations comprehend nearly all that is performed in what is called fitting."Do you know," I asked the officer, "that this old man and his grandchild are starving? He put me up because I gave him a couple of pieces of bread-and-butter for the child." He looked at me somewhat crossly, but inquired all the same whether my information was correct, and then gave the old man two loaves, which dried his tears immediately, and for which he thanked the donor in a quivering voice.
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