ut his plans
successfully. From each tower a steel arch was started on each side,
built of steel tubes braced securely; the building on each side of every
tower was carried on simultaneously, one side of every arch balancing
the weight on the other side. Each section was like a gigantic seesaw,
the tower acting as the centre support; the ends, of course, not
swinging up and down. 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

During the early part of the Spanish-American war a fleet of vessels
patrolled the Atlantic coast from Florida to Maine.