any was issued in 1843, the names of George Stephenson and
George Hudson appearing on the committee of management, Robert Stephenson
being the consulting engineer. The project was eventually taken up by
the Newcastle and Darlington Railway Company, and an Act for the
construction of the bridge was obtained in 1845.

The rapid extension of railways had given an extraordinary stimulus to
the art of bridge-building; the number of such structures erected in
Great Britain alone, since 1830, having been above 25,000, or more than
all that had before existed in the country. Instead of the erection a
single large bridge constituting, as formerly, an epoch in engineering,
hundreds of extensive bridges of novel design were simultaneously
constructed. The necessity which existed for carrying rigid roads,
capable of bearing heavy railway trains at high speeds, over extensive
gaps free of support, rendered it obvious that the methods which had up
to that time been employed for bridging space were altogether
insufficient. The railway engineer could not, like the ordinary road
engineer, divert his road and make choice of the best point for crossing
a river or a valley. He must take such ground as lay in the line of his
railway, be it bog, or mud, or shifting sand. Navigable rivers and
crowded thoroughfares had to be crossed without interruption to the
existing traffic, sometimes by bridges at right angles to the river or
road, sometimes by arches more or less oblique. In many cases great
difficulty arose from the limited nature of the headway; but, as the
level of the original road must generally be preserved, and that of the
railway was in a measure fixed and determined, it was necessary to modify
the form and structure of the bridge, in almost every case, in order to
comply with the public requirements. Novel conditions were met by fresh
inventions, and difficulties of the most unusual character were one after
another successfully surmounted. In executing these extraordinary works,
iron has been throughout the sheet-anchor of the engineer. In its
different forms of cast or wrought iron, it offered a valuable resource,
where rapidity of execution, great strength, and cheapness of
construction in the first instance, were elements of prime importance;
and by its skilful use, the railway architect was enabled to achieve
results which thirty years ago would scarcely have been thought possible.

In many of the early cast-iron br