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    Software name: appdown
    Software type: Microsoft Framwork

    size: 911MB

    Lanuage:Englist

    Software instructions

      For loading and unloading carts and waggons, the convenience of the old outside sling is well known; it is also a well-attested fact that accidents rarely happen with sling hoists, although they appear to be less safe than running platforms or lifts. As a general rule, the most dangerous machinery for handling or raising material is that which pretends to dispense with the care and vigilance of attendants, and the safest machinery that which enforces such attention. The condition which leads to danger in hoisting machinery is, that the power employed is opposed to the force of gravity, and as the force of gravity is acting continually, it is always ready to take advantage of the least cessation in the opposing force employed, and thus drag away the weight for which the two forces are contending; as a weight when under the influence of gravity is moved [65] at an accelerated velocity, if gravity becomes the master, the result is generally a serious accident. Lifting may be considered a case wherein the contrivances of man are brought to bear in overcoming or opposing a natural force; the imperfect force of the machinery is liable to accident or interruption, but gravity never fails to act. Acting on every piece of matter in proportion to its weight must be some force opposing and equal to that of gravity; for example, a piece of iron lying on a bench is opposed by the bench and held in resistance to gravity, and to move this piece of iron we have to substitute some opposing force, like that of the hands or lifting mechanism, to overcome gravity.


      Upon entering the shop, a learner will generally, to use a shop phrase, "be introduced to a hammer and chisel;" he will, perhaps, regard these hand tools with a kind of contempt. Seeing other operations carried on by power, and the machines in charge of skilled men, he is likely to esteem chipping and filing as of but little importance and mainly intended for keeping apprentices employed. But long after, when a score of years has been added to his experience, the hammer, chisel, and file, will remain the most crucial test of his hand skill, and after learning to manipulate power tools of all kinds in the most thorough manner, a few blows with a chipping hammer, or a half-dozen strokes with a file, will not only be a more difficult test of skill, but one most likely to be met with.Hetty murmured something to the effect that she had forgotten. There was no reason to contradict and argue over a child's fancies. Mamie murmured again.


      The pair looked at each other behind my neck for full ten seconds. Then the younger man leaned to his horse's mane in a silent laugh while Sergeant Jim looked me over again and remarked that he would be horn-swoggled!

      An interesting example in the use of belts for communicating power to movable machinery is furnished by the travelling cranes of Mr Ramsbottom, in the shops of the L. & N. W. Railway, at Crewe, England, where powerful travelling cranes receive both the lifting and traversing power by means of a cotton rope not more than three-fourths of an inch in diameter, which moves at a high velocity, the motion being reduced by means of tangent wheels and gearing to attain the force required in lifting heavy loads. Observing the operation of this machinery, a person not familiar with the relations between force and motion will be astonished at the effect produced by the small rope which communicates power to the machinery.


      XI CAPTAIN JEWETT

      "Never mind that," he said hoarsely. "I did find you out, and here I am. Oh, it was a cunning plot of yours--so near and yet so far away. And as much brandy as I could drink so that I might drink myself to death, and after that perhaps a handsome monument testifying to my virtues. But I'm not going to stand it any more, I'm not going back there."

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      It is no uncommon thing for a skilled latheman to lock the slide rest, and resort to hand tools on many kinds of work when he is in a hurry.

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      The gauging system has been no little retarded by a selfish and mistaken opinion that an engineering establishment may maintain peculiar standards of its own; in fact, relics of this spirit are yet to be met with in old machines, where the pitch of screw-threads has been made to fractional parts of an inch, so that engineers, other than the original makers, could not well perform repairing, or replace broken parts.Slowly Leona Lalage took the speaker in from head to foot. Her face had grown deadly pale. But she could make nothing of Lawrence's face. All the same, it was quite evident that he meant every word that he said.


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