GREAT RAILWAY SUSPENSION BRIDGE AT NIAGARA FALLS.

We have before, on page 265, given some account of this vast structure as it was, when so far completed as to be used for ordinary passage. But we advert to it again here, both because it has since had added to it the superstructure for railway-trains, and also that we may bring in comparison, the first suspension bridge ever attempted, (an account of which has been given,) and one of the last and largest ever undertaken. The first train of cars passed over this bridge on the ninth of March, 1855, from the Canada to the American shore, the engine and tender being crowded with people, having the English and American colors flying, while bands of music were playing alternately the national airs of Great Britain and of the United States. The opening of this mighty and magnificent structure, well worthy of being classed with the world’s wonders, really forms an epoch in the history of the world. It unites with strong iron bands two countries, to the intelligence and enterprise of whose inhabitants the bridge owes its existence, and stands a fitting monument. Its strength can never be fully tested; the weight of a fully laden train being but a trifle in comparison to its capacity. A train of eight cars, filled with passengers, two baggage-cars, locomotive and tender, weigh but about one hundred and thirty tuns; this being only one-sixtieth of its immense capacity. The railway portion of the bridge is leased to and controlled by the Great Western railway company, and has laid upon it tracks of three different gauges, viz., the New York Central, four feet and eight and a half inches; the Elmira and Niagara Falls, six feet; and the Great Western, five feet and six inches, thus affording facilities for the transit of both passengers and freight, without change of cars. The following statistics will give some idea of this immense structure and its capacity.

Length of span from center to center of towers,822feet.
Hight of tower above rock on the American side,88feet.
Hight of tower above rock on the Canada side,78feet.
Hight of tower above rock on the floor of railway,60feet.
Number of wire cables,4
Diameter of each cable,10inch.
Number of No. 9 wires on each cable,3,659
Ultimate aggregate strength of cables,12,409tuns.
Weight of superstructure,750tuns.
Weight of superstructure and maximum loads,1,250tuns.
Maximum weight the cable and stays will support,7,200tuns.
Hight of track above water,234feet.