Soon afterwards, in a great cast-iron arch thrown over the Spey, Telford made new experiments, and, as Professor Fleeming Jenkin has said, his bridge at Craigellachie marked “a great advance in the conception of what was the safest form in which to apply cast-iron to an arch.” But more than this was expected from an engineer of Telford’s reputation, and nothing more came from him, unfortunately. In fact, Telford divorced his work from the good sense of good design, which Darby and Burdon had endeavoured to respect. At each abutment he put up a silly tower pierced with arrow-slits and armed with battlements, advertising a farce of warlike make-believe which scores of foolish engineers would copy and adapt, while leaving their bridges entirely unfortified. A bridge here and there is supposed to be all right. Take, for instance, the Forth Bridge, with his 51,000 tons of steel, and his amazing cost, about £3,000,000; he is looked upon as a “safe” bridge, and safe he is if we forget what bombs and shells can do in a few seconds. At each end of this bridge the railway is carried by trivial columns forming the approach viaducts, and these a naval gun would blow to smithereens. A bomb falling upon them from an airship might put the whole bridge out of action. Further, the columns are comically out of scale with those gigantic pyramids of steel bars which counterbalance the centre girders, and yet seem to play at leapfrog in two bounds of 1710 ft. each, and in two lesser jumps of 680 ft. each. Yes, the Forth Bridge looks formidably alive and active; he is to modern engineering what the Ichthyosaurus became to our knowledge of prehistoric animals: a semi-marine colossus, fit to be kept for ever as a tremendous danger happily extinct.