Ship Canal Company. About the same time also they undertook the erection of the steelwork for the Tower Bridge across the Thames in London. This bridge in many respects is one of the most novel in Great Britain, having opening bascule spans in the centre, and a high-level footway overhead to allow of passenger traffic proceeding even while the bascule spans are open.
In the carrying out of this contract
PUBLISHED BY PERMISSION OF F. C. COFFIN, ASST. ENGINEER.
THE NEW TAY VIADUCT. PONTOON USED IN TRANSFERRING GIRDERS FROM THE OLD TO THE NEW PIERS.
it was necessary to stage the River Thames right across, with the exception of the centre opening. The piers were built of steel, with an outside covering of granite. The overhead footway is made up of cantilevers and central girders, and was erected in a manner somewhat similar to that adopted at the Forth Bridge. Before the central girder was joined up, to an observer standing on London Bridge it would seem that the two girders, coming out from the main piers, were at different levels. This, however, was merely an optical delusion, as the central girders met exactly, both as to line and level. After the piers and high-level roadways had been completed, the main chains were erected on a stage, and the approach from the river to the main piers was connected to the chains and completed. The opening ceremony was performed by the Prince of Wales in June, 1894.
The firm of Sir William Arrol & Co. do not confine themselves to the work of bridge-building, but carry on a very large general business in mechanical engineering and in all kinds of structural work. They manufacture to a very large extent the riveting machines patented by Sir William, which are adopted in most of the leading ship-building and iron centres throughout Great Britain, and also in other countries. In recent years they have also introduced and developed the Arrol-
