BRIDGES

BRIDGE

The first bridge was the trunk of a tree thrown across a channel, or a large slab placed upon stepping stones in a stream. Rope bridges, hammock bridges of vines, pontoon bridges with boats for supports these were among the types of bridges used in olden days, and still used in emergency or in out of the way places of the world. In the course of time came the arch bridge, the materials being either wood or brick, then stone.

Excavations on the site of Nineveh and Babylon show remains of brick arches dating back to four thousand years before Christ. A brick arch bridge, over six hundred feet long, is said to have been built over the Euphrates River within the city of Babylon about 200 b.c. It was composed of wooden platforms laid on stone piers. The first bridge to be composed entirely of iron was built in 1776 in England. Later, wrought iron took the place of cast iron, and about 1862 the first steel bridge appeared. The first steel arch, and the first steel railway bridge in America was the Eads Bridge over the Mississippi at St. Louis (1869-1874).