The subject of our large illustration this week is a large steel
bridge carrying the Central Pacific Railway over the St. Lawrence
River at Lachine, near Montreal. The main features of this really
magnificent structure are the two great channel spans, each 408 feet
long. It will be noticed that the design combines, in a very ingenious
manner, an upper and a lower deck structure, the railway track being
laid on the top of the girders forming the side spans, and on the
lower flanges of the channel spans, which are crossed by continuous
girders, 75 feet deep, over the central pier, and supported by
brackets as shown. The upper of our two engravings shows the method of
constructing the principal spans, which were built outward from the
side piers, while the work on the center pier was extended on each
side to meet. It was built at the works of the Dominion Bridge
Company, Montreal, from the design of Mr. C. Shaler Smith, the
well-known American bridge engineer.--_Engineering._
[Illustration]
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