Iron

This bridge is recognized as the first iron bridge in the world. This rural region of England was an important industrial area thanks to coal deposits near the surface. In 1776 the nearest bridge that enabled people and goods to pass over the River Severn was two miles away at Buildwas. There was a ferry crossing, but the trip was difficult and dangerous especially in winter. In 1776, an Act to build a bridge to remedy this situation received Royal Assent.

The design of the Bollman Truss Bridge-patented in 1852 and one of the first to use iron exclusively in all essential structural elements-was critical in the rapid expansion of American railroads in the 19th century. Replacing wooden bridges, which  were cumbersome to build and vulnerable to decay, the Bollman Truss Bridge could be built relatively quickly and inexpensively, while providing the long-lasting qualities associated with metal. This allowed new rail lines to be built over long distances in a short period of time.

A 214-foot single-span covered wooden bridge, built above the cribs of stone in the AuSable River that served to break log jams and ice floes, collapsed during the winter of 1875 under the weight of a three-foot snowfall and high winds. The "Upper Bridge" (pictured) was built in its place.

The drilling of this oil well marks the modern phase of the petroleum industry. A series of revolutionary technological changes, unforeseen even by the most prophetic, followed. Drake demonstrated practical oil recovery by applying salt-well drilling techniques, including the use of the derrick, and invented the modern method of driving iron pipe.