Suspension bridges are of very remote origin. One mentioned by Kirchen, still in use in China, was built, according to tradition, in the year A. D. 65; it is 330 feet long, a roadway of plank supported by chains. Rope suspension bridges were built by the ancient Peruvians, and they have been used in Europe. The first iron suspension bridge was built in 1819, across the Tweed, at Berwick-on-Tweed, by Captain Sir Samuel Brown. It was supported by chain cables, six 02a a side, and its span was 449 feet. The same engineer constructed the Brighton chain pier and the bridge at Montrose. The former was built in 1823, having four spans of 255 feet each; the latter was finished in l8 9, and nine years afterward was destroyed by a hurricane. The Menai suspension bridge was built by Telford in 1826. Its span was 580 feet, and hight above the water 102 feet. A violent gale produced such an oscillation that the chains were dashed against each other, and the heads of many of the bolts were broken. The chains were similar to those used on lathes, planers, etc., made of plates bolted or riveted together. The Conway bridge, connecting Chester and Bangor, also built by Telford, has a span of 327 feet. It was built in 1826. The Freyburg (Switzerland) bridge is suspended by wire cables, and has a span of 870 feet. In the United States, the most remarkable suspension bridges are Ellet's Wheeling bridge over the Ohio, with a span of 1,010 feet; erected in 1848, and blown down in 1854. The Lewiston bridge, seven miles below Niagara Falls, built by E. W. Serrell, spanned 1,040 feet. Roebling's bridge, at the falls, spans 821 feet; McAlpine's new Niagara bridge has a span of 1,264 feet, and the proposed bridge to connect New York and Brooklyn is to have a span of 1,600 feet. The bridge seen in the full-page engraving crosses the Ohio River from Cincinnati, Ohio, to Covington, Ky., and has a span of 1,057 feet, with an elevation of roadway of 103 feet. This elevation is the mean, extreme cold raising the bridge, by contraction of the cables, twelve inches, and extreme summer heat allowing it to sink the same distance. At a mean temperature of 60 deg. the hight is 103 feet. The foundations of the towers were begun in September, 1856. Work was Suspended in 1857, and not resumed until 1863. The bridge was opened for travel for foot passengers Dec. 1, 1866, and for Carriages one month later. At the water level the space between the towers on either shore is 1,005 feet. The floor of the bridge is composed of a strong wroughtriron frame overlaid with several thicknesses of plank, and suspended to two wire cables by suspenders placed every five feet. The suspenders are between the roadway and footpaths, the former being twenty feet and the latter seven feet wide. No lateral or transverse stays or guys are employed in this bridge, the requisite stiffness being assured by two wrought-iron girders extending from abutment to abutment, and running through the center line of the bridge, under and over the floor beams. One is twelve and the other nine inches deep, the former under the beams and the latter over, secured together and to the beams by bolts, thus making a combined and continuous girder of a depth of twenty-eight inches. The base of each tower is 82 by 52 feet, with a hight of 165 feet to the spring of the arch The towers are buttressed from foundation to top. On the Ohio side the substructure is similar to that proposed for the New York tower of the proposed East River bridge a mass of timber work resting on compacted Sand, ancfrfirmly bolted together, the whole infilled With concrete grouting The depth excavated on this side was so great that most of the wells in the vicinity were drained. The total weight of one tower is estimated at 60,-000,000 pounds. The cables are two in number, twelve and one-third inches diameter, composed each of 5,180 wires of No. 9 gage, twisted in situ, and overlaid with No. 10 wire, the total weight of \vire used being 1,050,183 pounds. Each cable rests upon cast iron saddles at the top of the towers, each saddle resting upon 82 rollers. The bridge is the work of the celebrated engineer, John A. Roebling, to whom we are indebted for the facts herein stated. The view in the engraving is taken from the Kentucky shore.