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A Treatise of Mechanics, Theoretical, Practical, and Descriptive
A Treatise of Mechanics Theoretical Practical and Descriptive Author:Olinthus Gregory Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: MECHANICS. Remarks on Machinery in General. 1. Mechanics, according to the original import of the word, treats of the energy of Machines: and these machine... more »s arc nothing more than organs, or tools, interposed between the workman, or natural agent, and the task to be accomplished, in order to render that work capable of being performed, which under the limits and circumstances proposed would have been difficult, if not impossible, without die intervention of some of these contrivances. Machines are interposed, as was remarked (art. 379. vol. I.), chiefly for three reasons. 1. To accommodate the direction of the moving force, to that of the resistance which is to be overcome. 2. To render a power which lias a fixed and certain velocity efficacious in performing work with a different velocity. 3. To enable a natural power, having a certain determinate intensity, to balance or to overcome another power or obstacle, whose intensity or resistance is greater. Each of these purposes may be accomplished indifferent ways : i.e. either by machines which have a motion round some fixed and supported point, as the lever, the pulley, and the wheel and axle; or by those which, instead of being supported by a fixed point, about which they move, furnish to the resistance, or body to be moved, a solid path, along which it is impelled, as the inclined plane, the wedge, and the screw. Compound machines are peculiar combinations of these six, of which we have treated individually in the first book of our first volume: some remarks likewise upon their combination have been given in Book 1. Chap. IV. art. 161. and Book II. Chap. VI. And we have treated of the strength of the materials of which machines may be composed, in Book I. Chap. V. Such farther observations as appear necessary to complete ...« less