Gradually the two sections of every arch approached each other until they met over the turbid water and were permanently connected. With the completion of the three arches, built entirely from the piers supporting them, the great stream was spanned. The Eads Bridge was practically a double series of cantilevers balancing on the towers. Three arches were built, the longest being 520 feet long and the two shorter ones 502 feet each. Every situation that confronts the bridge builder requires different handling; at one time he may be called upon to construct a bridge alongside of a narrow, rocky cleft over a rushing stream like the Royal Gorge, Colorado, where the track is hung from two great beams stretched across the chasm, or he may be required to design and construct a viaduct like that gossamer structure three hundred and five feet high and nearly a half-mile long across the Kinzua Creek, in Pennsylvania. Problems which have nothing to do with mechanics often try his courage and tax his resources, and many difficulties though apparently trivial, develop into serious troubles. The caste of the different native gangs who worked on the twenty-seven viaducts built in Central Africa is a case in point: each group belonging to the same caste had to be provided with its own quarters, cooking utensils, and camp furniture, and dire were the consequences of a mix-up during one of the frequent moves made by the whole party. [Illustration: BEGINNING AN AMERICAN BRIDGE IN MID-AFRICA] And so the work of a bridge builder, whether it is creating out of a mere jumble of facts and figures a giant structure, the shaping of glowing metal to exact measurements, the delving in the slime under water for firm foundations, or the throwing of webs of steel across yawning chasms or over roaring streams, is never monotonous, is often adventurous, and in many, many instances is a great civilising influence. SUBMARINES IN WAR AND PEACE