"The for many years have striven hard to obtain a physical connection of their lines north and south of the Forth by means of a bridge. Twenty years ago they were authorized by to build a bridge across the Forth at a point five miles above the site now under construction., but borings 120 feet in depth showed nothing but soft silt and mud, and the bridge, which was to have been two miles in length, inclusive of the four spans of 500 feet each, was luckily abandoned, as the difficulties with the foundation would have proved practically insuperable. In 1873 another Act was passed for a bridge across a narrower and deeper part of the Forth at . At low water the width of the channel there is about 4,000 feet; and the island of affording a foundation for a central pier, it was possible to cross the 200 feet deep portion of the sea-way by a couple of spans from 1,600 feet to 1,700 feet each in the clear."