A Memoir of Suspension Bridges: Comprising the History of Their Origin and Progress, and of Their Application to Civil and Military Purposes, with Descriptions of Some of the Most Important Bridges; Viz. Menai, Berwick, Newhaven, Geneva, Etc. Also an Account of the Experiements of the Strength of Iron Wires and Iron Bars, and Rules and Tables for Facilitating Computations Relating to Suspension Bridges

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Longmans, Rees, Orme, Brown, Green & Longman, 1832 - Bridges - 211 pages
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Page 3 - The rope used in forming the bridge is generally from two to three inches in circumference, and at least nine or ten times crossed, to make it secure. This collection of ropes is traversed by a block of wood, hollowed into a semicircular groove, large enough to slide easily along it; and around this block ropes are suspended, forming a loop in which passengers seat themselves, clasping its upper parts with their hands, to keep themselves steady ; a line fixed to the wooden block at each end, and...
Page 50 - ... platform They are here put together, and each frame raised by the suspending chain bars, and other means, so that the end which is to be joined to the frame already fixed shall rest upon a small move-able carriage. It is then to be pushed forward, perhaps upon an iron rail-road, until the strong iron forks which are fixed upon its edge shall fall upon a round iron bar, which forms the outer edge of the first, or abutment frames. When this has been done, strong iron bolts are put through eyes...
Page 49 - Next to the face of the abutment one set of frames, about fifty feet in length, can, by means of temporary scaffolding and iron chain bars, be readily constructed, and fixed upon the masonry offsets of the abutment, and to horizontal iron ties laid into the masonry for this purpose. A set of these frames (four in number) having been fixed against the face of each abutment, they are to be secured together by cross and diagonal braces ; and there being spaces of only...
Page 3 - At some convenient spot, where the river is rather narrow and the rocks on either side overhang the stream, a stout beam of wood is fixed horizontally upon or behind two strong stakes, that are driven into the banks on each side of the water; and round these beams ropes are strained, extending from the one to the other across the river, and they are hauled tight, and kept in their place, by a sort of windlass. The rope used in forming...
Page 210 - A suspension bridge, moreover, on a great military pass, would give the inhabitants greater command over it j for by knocking out a few connecting bolts, a whole bridge might be dismantled very rapidly, without being destroyed, to check or retard the enemy's passage ; whereas, to cut off the passage of a stone bridge, it must be blown up, and cannot be renewed but with great expense and loss of time.
Page 49 - By the nature of the framing, and from its being secured by horizontal and suspending bars, I presume every person accustomed to practical operations, will admit that these platforms may be rendered perfectly firm and secure." " The second portion of the centering frames having been previously prepared and fitted together in the carpenter's yard, are brought in separate pieces, through passages purposely left open in the masonry to the before mentioned platform.
Page 209 - ... a light one. The object, therefore, in building a suspension bridge is, either to make it so light that its own vibration shall not hurt it ; or if, as in nine cases out of ten, that cannot be done, then to make it so heavy and stiff, in proportion to the load it will have to carry, that the load shall not cause it to vibrate much. This, for a bridge liable to be constantly loaded with as much as it could contain, would be impracticable.
Page 3 - The j,hoola at Rampore was somewhat formidable, for the river tumbles beneath in a very awful way ; and the ropes, though they decline in the centre to the water, are elevated from thirty to forty feet above it ; the span is from ninety to a hundred yards.
Page 49 - These frames to be about 50 feet high above the top of the masonry ; and to be rendered perfectly firm and secure. That this can be done, is so evident, I avoid entering into details respecting the mode. These frames are for the purpose of receiving strong blocks or rollers and chains, and to be acted upon by windlasses or other powers.
Page 3 - ... of wood hollowed into a semicircular groove large enough to slide easily along it, and around this block ropes are suspended, forming a loop, in which passengers seat themselves, clasping its upper parts with their hands to keep themselves steady; a line fixed to the wooden block at each end, and extending to each bank, serves to haul it, and the passenger attached to it. from one side of the river to the other...

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