Engineering Wonders of the World
Volume I

152 ENGINEERING WONDERS OF THE WORLD. All the Tubes raised. yard, would tower 100 feet above the great cross, were set in their respective places, each track joined to- continuous long, and All four tubes for of rails were then gether to form a girder, 1,511 feet odd tons, attached firmly to weighing 5,000 the Britannia Tower, but resting upon rollers on the two land piers and the abutments, to allow for expansion and contraction of the metal. On March 5, 1850, the now completed bridge was subjected to severe tests. locomotives, Testing- the Bridge. First, three coupled together, were moved across ; then a train of twenty- four loaded coal wagons ; and finally a heavy testing train of several hundred tons crossed 35 miles an hour. The deflec- at a speed of tion caused by the load was less than half an inch, or barely one twenty-fifth of that to which, the bridge might be subjected with- out danger. As Stephenson had designed the bridge to stand eight times the maximum load that could possibly be put upon it by an ordinary train, the slightness of the deflection was anticipated. Though the weight of loco- motives and other rolling stock has increased greatly during the last half century, and nearly sixty years have passed since the opening of An Appreciation of the Bridge. the bridge, there lias been no talk of replacing Stephenson’s great structure by one of more modern design. “ The Britannia Bridge,” wrote Dr. Smiles, “ is one of the most remarkable monuments of the enterprise and skill of the present [nine- teenth] century. Robert Ste- phenson was the master spirit of the undertaking. To him belongs the merit of first seiz- ing the ideal conception of the structure best adapted to meet the necessities of the case, and of selecting the best men to work out his idea ; himself watching, control- ling, and testing every result by independent check and counter-check. “ But for the perfection of our tools, and the ability of our mechanics to use them, to the greatest advantage ; but for the matured powers of the steam-engine ; but for the im- provements in the iron manufacture, which enabled blooms to be puddled of .sizes before deemed impracticable, and plates and bars of immense size to be rolled and forged,—but for these, the Britannia Bridge would have been designed in vain. Thus it was not the pro- duct of the genius of the railway engineer alone, but of the collective mechanical genius of the English nation.” END-ON VIEW OF THE BRIDGE. (From an Old Print, by permission of the London and North - Western Railway Com- pany.)