Machinery

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Page 46 - The centre of gravity of a body is not always within the body itself : thus the centre of gravity of a ring is not in the substance of the ring, but in the axis of its circumscribing cylinder ; and the centre of gravity of a hollow staff, or of a bone, is not in the matter of which it is constituted, but...
Page 217 - The absolute command of draft for the generation of the required quantity of steam, to enable the engines to work to their full power, being then so essential, it becomes a question whether other means than the natural draft should not be resorted to ; since, independently of the uncertainty in the amount of draft, and the consequent irregularity in the working effect of the engines, the cost of sustaining that draft may be so much in excess of what an artificial draft would be.
Page 282 - I have actually made about ten gallons of liquid air in my liquefier by the use of about three gallons in my engine. There is, therefore, a surplusage of seven gallons that has cost me nothing, and which I can use elsewhere as power.
Page 62 - a bar of metal, wood or other substance, used to exert a pressure or to sustain a weight, at one point at its length, by receiving a force or power at a second, and turning at a third on a fixed point called a fulcrum. It is of three kinds, according as either the fulcrum F , the weight W, or the power P, respectively, is situated between the other two.
Page 360 - The subdivision of the work commonly performed on metal-worKing machine tools may be briefly outlined as follows: First — Turning and Boring ; as performed in the lathe, screwmachine, turret-machine, vertical boring mill, etc., in which the work is usually made to rotate to a cutting tool or tools which, aside from feeds, are stationary. This operation usually produces curved or circular surfaces, both internal and external, but may, as in facing, produce a plane surface. Second — Planing Operations;...
Page 42 - Further, for the sake of simplicity, it will be assumed that the load, P, acts on the outer circumference of the gear, and hence at the extremity of the tooth. If we consider the conditions under which the load is assumed to be applied in actual practice, we shall find that: (1) A rough cast gear may have the whole load concentrated upon one corner of a tooth; or the gear itself may be well made, but may be out of alignment, due to springing of shaft, bad workmanship or other causes; in this case...
Page 160 - Such joints are as serious mistakes in design as would be a joint in the middle of a girder under a heavy load. 3. Joints made in the ordinary manner, with internal flanges and bolts, are probably the worst that could be devised for this purpose. Under the most favorable circumstances they have only about one-fourth the strength of the solid rim and are particularly weak against bending. In several joints of this character, on large fly-wheels, calculation has shown a strength less than one-fifth...
Page 45 - The area of any irregular figure bounded by straight lines may be found by dividing it up into triangles, and then adding together the areas of the triangles.
Page 62 - An expansion of their mass along the planes of cleavage in the direction of a line at right angles to the line of incidence of the planes of bedding and cleavage ; or in other words, in the direction of the dip of the cleavage.

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