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    Software name: appdown
    Software type: Microsoft Framwork

    size: 855MB

    Lanuage:Englist

    Software instructions


      Second.The steam establishes the greatest possible elasticity in the connection between a hammer and the driving power, and at the same time serves to cushion the blows at both the top and bottom of the stroke, or on the top only, as occasion may require.


      (1.) What is the difference between geometric and artistic drawing?(2.) What is the most important operation in making a good drawing?(3.) Into what three classes can working drawings be divided?(4.) Explain the difference between elevations and plans.(5.) To what extent in general practice is the proportion of parts and their arrangement in machines determined mathematically?

      I asked him how things were farther on along the Meuse, but he knew nothing. He was stationed here, he said, and was going to stay as long as possible. As soon as the Germans arrived, most people fled, and those who had stayed on were no longer allowed to leave. So he lacked all information, and only understood that fierce fighting was going on, as was confirmed by the incessant thunder of the20 guns. Fort Pontisse was, moreover, not so very far away, and frequently we could distinctly tell, by their whistling sound, in which direction the shells flew.Irregularity of cooling may be the result of unequal conducting power in different parts of a mould or cores, or it may be [98] from the varying dimensions of the castings, which contain heat as their thickness, and give it off in the same ratio. As a rule, the drag or bottom side of a casting cools first, especially if a mould rests on the ground, and there is not much sand between the castings and the earth; this is a common cause of unequal cooling, especially in large flat pieces. Air being a bad conductor of heat, and the sand usually thin on the cope or top side, the result is that the top of moulds remain quite hot, while at the bottom the earth, being a good conductor, carries off the heat and cools that side first, so that the iron 'sets' first on the bottom, afterwards cooling and contracting on the top, so that castings are warped and left with inherent strains.

      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 the rest the transports were not much troubled now, for obviously the bridge was no longer the objective of the Belgian guns. At Vis I was even told that Fort Pontisse had just been57 taken and only Lierce could harass the troops, who, after crossing the bridge, advanced towards Tongeren.


      In the meantime they themselves had a word or two to say about the fright I gave them; for when I stood at the door they mistook me in my sporting habit for a German officer, and the top of my water-bottle for the butt of a revolver!

      This brings us back to the old proposition, that for structures which do not involve motion, mathematical data will furnish dimensions; but the same rule will not apply in machinery. To follow the proportions for shafts that would be furnished by pure mathematical data would in nearly all cases lead to error. Experience has demonstrated that for ordinary cases, where power is transmitted and applied with tolerable regularity, a shaft three inches in diameter, making one hundred and fifty revolutions a minute, its bearings three to four diameters in length, and placed ten feet apart, will safely transmit fifty horse-power.Two facts are made clear by Mr. Mokveld's book, if, indeed, the world has ever doubted them. The first is that the German authorities, believing their victory to be beyond question, deliberately sanctioned a campaign of frightfulness. They did not imagine that they would ever be held to account. They wished to terrorise their opponents by showing them what resistance involved. The atrocities were not the blunders of drink-sodden reservists, but the result of the theories of half-witted military pedants. The second is that the invading armies were as nervous as a hysterical woman. Those would-be conquerors of the world were frightened by their own shadows. A shot fired by accident from a German rifle led to tales of attacks by Belgian francs-tireurs and then to indiscriminate murder by way of revenge. Mr. Mokveld examined the legends of treacherous Belgian assaults and the 7 mutilation of the German wounded, and found them in every case wholly baseless. No German had ever seen these things happen, but had only heard of them. When definite details were given, Mr. Mokveld tracked them down and found them false. The Belgian atrocities lacked even that slender justification which belongs to reprisals. They were the work of a drunken and "rattled" soldieryfor fear is apt to make men brutaldeliberately encouraged by the authorities, who for this purpose relaxed the bonds of military discipline. When the battle of the Marne changed the complexion of affairs, these authorities grew scared and repudiated the policy, but Belgium remains a witness of what Germany's triumph means for her victims.

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      I felt not the slightest inclination to go and see what was the matter, but I stretched myself and yawned, feeling much more tired after a couple of hours' rest than when I went to bed. The uproar went on, and suddenly I thought that I also heard a hubbub in the caf downstairs. And, really, it came ever nearer. People rushed up and down the stairs, screamed and yelled, doors were banged, in short it was as if they were pulling down the house.CHAPTER XXVIII. TEMPERING STEEL.

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      As soon as the Reverend Head, Dr. Frits Goffin, saw me he burst out sobbing, and, taking me by the hand, speechless, he pressed it a long time. I myself also was quite dumb. At length he muttered:Although a system but recently developed, the employment of hydraulic machinery for transmitting and applying power has reached an extended application to a variety of purposes, and gives promise of a still more extensive use in future. Considered as a means of transmitting regularly a constant amount [54] of power, water apparatus is more expensive and inferior in many respects to belts or shafts, and its use must be traced to some special principle involved which adapts hydraulic apparatus to the performance of certain duties. This principle will be found to consist in storing up power in such a manner that it may be used with great force at intervals; and secondly, in the facilities afforded for multiplying force by such simple mechanism as pumps. An engine of ten-horse-power, connected with machinery by hydraulic apparatus, may provide for a force equal to one hundred horse-power for one-tenth part of the time, the power being stored up by accumulators in the interval; or in other words, the motive power acting continuously can be accumulated and applied at intervals as it may be required for raising weights, operating punches, compressive forging, or other work of an intermittent character. Hydraulic machinery employed for such purposes is more simple and inexpensive than gearing and shafts, especially in the application of a great force acting for a considerable distance, and where a cylinder and piston represent a degree of strength which could not be attained with twice the amount of detail, if gearing, screws, levers, or other devices were employed instead.

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      My "foreign" passport was, of course, in French, of which language the man evidently knew not a word. Although I explained that this passport was the best one could get in The Netherlands, that I had paid six guilders and seventy-five cents for it, that I was a war-correspondent of De Tijd, it was all useless. I had to go with him to the guard-house, and the man kept the queer passportthe damning piece of evidencefirmly in his hand. All the inquisitive loafers, of which the frontier was full during those days, followed me, and so we went in procession to the guard-house, at some distance from the frontier. I heard all sorts of discussions behind me, and constantly caught words like: German, boche, deserter, franc-tireur, spy, and other complimentary niceties.


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