The Conway bridge consists of a tube, or long, huge chest, the ends of
which rest upon stone piers, built to correspond with the architecture
of the old castle. The tube is made of wrought-iron plates, varying in
thickness from a quarter of an inch to one inch, riveted together, and
strengthened by irons in the form of the letter T; and, to give
additional strength to the whole, a series of cells is formed at the
bottom and top of the tube, between an inner ceiling and floor and the
exterior plates; the iron plates which form the cells being riveted and
held in their places by angle irons. The space between the sides of the
tube is 14 feet; and the height of the whole, inclusive of the cells, is
22 feet 3-1/2 inches at the ends, and 25 feet 6 inches at the centre.
The total length of the tube is 412 feet. One end of the tube is fixed
to the masonry of the pier; but the other is so arranged as to allow for
the expansion of the metal by changes of the temperature of the
atmosphere, and it therefore, rests upon eleven rollers of iron, running
upon a bed-plate; and, that the whole weight of the tube may not be
carried by these rollers, six girders are carried over the tube, and
riveted to the upper parts of its sides, which rest upon twelve balls of
gun-metal running in grooves, which are fixed to iron beams let into the
masonry.
Pages:
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341