ost formidable. It is
about two miles long, and in some parts 80 feet deep. It is a narrow
ravine or defile cut out of the solid rock; and not less than 480,000
cubic yards of stone were removed from it. Mr. Vignolles, afterwards
describing it, said it looked as if it had been dug out by giants.

The crossing of so many roads and streams involved the necessity for
constructing an unusual number of bridges. There were not fewer than 63,
under or over the railway, on the 30 miles between Liverpool and
Manchester. Up to this time, bridges had been applied generally to high
roads where inclined approaches were of comparatively small importance,
and in determining the rise of his arch the engineer selected any headway
he thought proper. Every consideration was indeed made subsidiary to
constructing the bridge itself, and the completion of one large structure
of this sort was regarded as an epoch in engineering history. Yet here,
in the course of a few years, no fewer than 63 bridges were constructed
on one line of railway! Mr. Stephenson early found that the ordinary
arch was inapplicable in certain cases, where the headway was limited,
and yet the level of the railway must be preserved. In such cases he
employed simple cast-iron beams, by which he safely bridged gaps of
moderate width, economizing headway, and introducing the use of a new
material of the greatest possible value to the railway engineer. The
bridges of masonry upon the line were of many kinds; several of them
askew bridges, and others, such as those at Newton and over the Irwell at
Manchester, straight and of considerable dimensions; but the principal
piece of masonry was the Sankey viaduct.

[Picture: Sankey Viaduct]

This fine work is principally of brick, with stone facings. It consists
of nine arches of fifty feet span each. The massive piers are supported
on two hundred piles driven deep into the soil; and they rise to a great
height,--the coping of the parapet being seventy feet above the level of
the valley, in which flow the Sankey brook and canal. Its total cost was
about 45,000 pounds.

By the end of 1828 the directors found they had expended 460,000 pounds
on the works, and that they were still far from completion. They looked
at the loss of interest on this large investment, and began to grumble at
the delay. They desired to see their capital becoming productive; and in
the spring of 1829 they urged the en