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    Software name: appdown
    Software type: Microsoft Framwork

    size: 785MB

    Lanuage:Englist

    Software instructions

      A great share of the alleged improvements in machinery, when investigated will be found to consist in nothing more than the combination of several functions in one machine, the novelty of their arrangement leading to an impression of utility and increased effect.


      "No, sir, we must hope for the best."Many of the most accurate measurements are, however, performed by sight, with vernier calipers for example, the variation being multiplied hundreds or thousands of times by mechanism, until the least differences can be readily seen.


      Isometrical perspective is often useful in drawing, especially in wood structures, when the material is of rectangular section, and disposed at right angles, as in machine frames. One isometrical view, which can be made nearly as quickly as a true elevation, will show all the parts, and may be figured for dimensions the same as plane views. True perspective, although rarely necessary in mechanical drawing, may be studied with advantage in connection with geometry; it will often lead to the explanation of problems in isometric drawing, and will also assist in free-hand lines that have sometimes to be made to show parts of machinery oblique to the regular planes. Thus far the remarks on draughting have been confined to manipulation mainly. As a branch of engineering work, draughting must depend mainly on special knowledge, and is not capable of being learned or practised upon general principles or rules. It is therefore impossible to give a learner much aid by searching after principles to guide him; the few propositions that follow comprehend nearly all that may be explained in words.3. The saving from condensation, to which steam is exposed, avoidance of heat, and the consequent contraction and expansion of long conducting pipes.

      He thought that it was sufficiently protected by the immense Red Cross flag, and the words written on the door by the Germans themselves: "Professor Noyons, Netherland physician, to be spared." But he had been mistaken. The soldiers did not respect anything, and had forced an entry into the house, wounded that servant, and then wrecked everything in the most scandalous manner. Beautiful large Japanese jars had been smashed to pieces, valuable furniture damaged by knocking and breaking large pieces out of it with rifles and bayonets. A fine carpet was burned, as well as many pieces of furniture. A hole was burned even in the floor."It is a pity, sir, that you did not arrive a day sooner, then you might have witnessed great barbarity of the Germans. If you walk on a little farther along the canal, you will see three persons hanging from a tree near Haccourt; one of these is a boy of fourteen. Nobody was allowed on the road, and as a patrol met these three persons, they concluded immediately that they were francs-tireurs, strung them up on the tree, without a trial of any sort, and in addition shot each a bullet through the head. To-day another patrol arrived and had the effrontery to tell the members of the Maastricht Red Cross that the boy had murdered a captain. And we are not allowed to remove the corpses. Horrible!... horrible!"

      I was the only civilian in that road, and the soldiers, with much curiosity, stared at me. Whenever I noticed an officer, I gave an elaborate military salute, and with such an air that the officers, although hesitating at first, did not fail to return the salute.


      A planing machine platen, for instance, moves at a uniform rate of speed each way, and by its own motion shifts or reverses the driving power at each extreme of the stroke. Presuming that there were no examples to be examined, an apprentice would find many easier problems to explain than how a planing machine can shift its own belts. If a platen or table disengages the power that is moving it, the platen stops; if the momentum carries it enough farther to engage or connect other mechanism to drive the platen in the opposite direction, the moment such mechanism comes into gear the platen must stop, and no movement can take place to completely engage clutches or shift belts. This is a curious problem that will be referred to again.

      "It mourns the lost liberty, the happiness, the peace, the brightness of her past prosperity which has vanished for a long season to come, it laments on account of the prisoners of war, the wounded, the dead.... And every morning the155 brilliant sun rises on the scene, the warm rays bathe town and country, both alike cruelly lashed by the frightful scourge.

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      In shading drawings, be careful not to use too deep tints, and to put the shades in the right place. Many will contend, and not without good reasons, that working drawings require no shading; yet it will do no harm to learn how and where they can be shaded: it is better to omit the shading from choice than from necessity. Sections must, of course, be shadednot with lines, although I fear to attack so old a custom, yet it is certainly a tedious and useless one: sections with light ink shading of different colours, to indicate the kind of material, are easier to make, and look much better. By the judicious arrangement of a drawing, a large share of it may be in sections, which in almost every case are the best views to work by. The proper colouring of sections gives a good appearance to a drawing, and conveys an idea of an organised machine, or, to use the shop term, "stands out from the paper." In shading sections, leave a margin of white between the tints and the lines on the upper and left-hand sides of the section: this breaks the connection or sameness, and the effect is striking; it separates the parts, [85] and adds greatly to the clearness and general appearance of a drawing.

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      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.This terrible tragedy took place at scarcely six yards from the Netherland frontier, for the burgo101master's house stands by a road half Belgian and half Netherland. The Netherland soldiers who were doing frontier-duty on the latter part had to fly from the mad shooting of the Germans. They hid behind a wall that was quickly full of bullet-holes. The German soldiers spent a considerable time guzzling the burgomaster's wine, which they looted, and afterwards went off in the direction of Tongres.

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      It will be well for an apprentice to begin at once, as soon as he commences a shop course, to note the manner of handling material, watching the operation of cranes, hoists, trucks, tackle, rollers; in short, everything that has to do with moving and handling. The machinery and appliances in ordinary use are simple enough in a mechanical sense, but the principles of handling material are by no means as plain or easy to understand. The diversity of practice seen in various plans of handling and lifting weights fully attests the last proposition, and it is questionable whether there is any other branch of mechanical engineering that is treated less in a scientific way than machinery of this class. I do not allude to the mechanism of cranes and other devices, which are usually well proportioned and generally well arranged, but to the adaptation of such machinery with reference to special or local conditions. There are certain inherent difficulties that have to be encountered in the construction and operation of machinery, for lifting and handling, that are peculiar to it as a class; among these difficulties is the transmission of power to movable mechanism, the intermittent and irregular application of power, severe strains, also the liability to accidents and breakage from such machinery being controlled by the judgment of attendants.My poor informants had not yet made up their mind where to go, fearing that they might not be permitted to enter The Netherlands as they were without means of subsistence. I assured them, however, that our conception of neighbourly love and charity was different, and that they would be hospitably received.


      alllittle