[Illustration: THE CLIFTON BRIDGE.] In its day, this stupendous bridge was as great a wonder as its later companion over the same Straits—the Britannia Tubular. Six years were occupied in building, and it was opened in 1825. Why, then, did not Stephenson construct a similar bridge when, twenty years or so later, he had to solve a similar problem? The answer is, that suspension bridges are not—or were not—considered sufficiently strong and rigid for railway work. In America, however, they have been used for this purpose; witness the famous Niagara Suspension Bridge, 2⅓ miles below the Falls, and with a superb span of 822 feet; but American engineers appear to stiffen the roadway considerably, so as to distribute the stress of the rushing train over a large portion of the cable. The Niagara Bridge is not supported by plate-link chains, but by four immense wire cables, stretching from cliff to cliff over the roaring rapids. Four thousand distinct wires make up each cable, which pass over lofty piers, and from them hangs the railway by numerous rods. [Illustration: THE BROOKLYN BRIDGE.] Probably the famous Brooklyn Bridge is the largest suspension bridge in the world, even as the Clifton Suspension Bridge, in England, is one of the most interesting. The Brooklyn Bridge has a magnificent central span of 1595½ feet over the East River between Brooklyn and New York; further, there are two land spans of 930 feet, which, together with the approaches, make up a total of about a mile and a furlong. The cables, four in number, are each composed of 5000 steel wires, and measure 15¾ inches in diameter. They are anchored to solid stone structures at either end, measuring 119 feet by 132 feet, and weighing 60,000 tons; while the towers from which the main span is suspended rise to the height of 276 feet, and are embedded in the ground 80 feet below high-water. It has been estimated that the weight hung between these towers is nearly 7000 tons. The roadway of the bridge is divided into five thoroughfares. Those on the outer sides are for vehicles, and are 19 feet wide; the centre is for foot passengers, and is 15½ feet in width; while the two others are for tramway traffic. The bridge was opened in 1883, and affords a great triumph of engineering skill. Much smaller, but none the less interesting, is the Suspension Bridge at Clifton. As far back as 1753, Alderman William Vick, of Bristol, left a sum of £1000 to build a bridge at Clifton. The sum was to lie at compound interest until £10,000 was reached. However, the money was increased by subscriptions, and in 1830 an Act of Parliament was obtained for its construction. The work coming into the hands of Mr. I. K. Brunel, he designed a bridge of 702 feet span, and 250 feet above high-water. The piers and abutments were built, but lack of cash, which forms an obstacle to so many brilliant enterprises, stopped the progress of the bridge for nearly fourteen years.