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SIDE PLATES.

Beginning at the centre, and strengthened by Tee bars inside and out, placed at distances of 3', 6",

The first space of 35 feet from the centre is formed of inch plate.

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Keelsons, 10 inches in depth, are placed transversely at distances of 7 feet, and secured to the side Tee bars by gussets, for the support of the longitudinal timbers carrying the rail.

The top of the tube is also supported by keelsons at the same distances apart, and the whole tube rendered rigid, by stiffening gussets and double covers over every joint.

The wrought iron in a single tube 258 feet in length, including its bearings over the piers, weighs about a ton to the running foot, or 258 tons in all.

The central tube, in consequence of its increased length, is somewhat different in its arrangement; the bottom and top being proportionally stronger,-the first with an additional thickness of plates, and the last, with longitudinal keelsons 10" high, taking the place of the ordinary longitudinal Tee bars, as existing on the side tubes; the side plates are 2 feet, instead of 3 feet wide, with a proportionately larger number of side Tee bars. The whole tube is disconnected from the others, being bolted to pier No. 12, and resting on rollers on No. 13 pier.

Windows are introduced into the sides of the tubes near the line of neutral axis, and serve to light up the inside. Iron brackets are placed on the piers where not

occupied by the tubes, and slope back to the top of the tubes, but are entirely disconnected from it. They serve to give a finished appearance, and likewise prevent the snow and rain blowing in through the openings left for expansion and contraction.

It was originally intended to cover the top of the tubes with a curved corrugated iron roof, to protect them from the weather. This design was subsequently abandoned and the present sloping angular one substituted, composed of grooved and tongued boards, covered with the best quality of tin. This tin is not put on in the usual manner, but, by an ingenious arrangement, each sheet is allowed to expand and contract at pleasure, without the danger of destroying the fastenings which attach it to the timber underneath, as in the ordinary method made use of, and thus insures its continual efficiency.

A foot-walk 26 inches in width extends along the top of the roof, the whole length of the tubes, for the convenience of the employés connected with the work; a track is also provided for the painting-travellers.

The contract price may be put down under the heads of,

First-The approaches and abutments, which together extend
to 3,000 feet in length, amount in the estimate to....
Second-The masonry forming the piers, which occupy the inter-
vening space of 7,000 feet between the abutments, including
all dams and appliances for their erection... ...
Third. The wrought-iron tubular superstructure, 7,000 feet in
length, which amounts to...

$1,000,000

4,000,000

2,000,000

(About $285.70 per lineal foot), making a total of .......... $7,000,000

The following interesting details are annexed by Mr. Legge:

First stone, No. 1 Pier, laid 20th July, 1854.

First passenger train passed 17th December, 1859.

Total length of Bridge, 9,184 feet lineal.

Number of spans, 25; 24 of 242 feet; one of 330 feet.

Height from surface of water to under side of centre tube, 60 feet.

Height from bed of river to top of centre tube, 108 feet.

Greatest depth of water, 22 feet.

General rapidity of current, 7 miles an hour.

Cubic feet of masonry, 3,000,000.

Cubic feet of timber, in temporary work, 2,250,000.
Cubic yards of clay used in puddling dams, 146,000.
Tons of iron in tubes, say, 8,250.

Number of rivets, 2,500,000.

Acres of painting on tubes, one coat, 30; or for the four coats, 120 acres. Length of abutments, 242 feet each.

แ of north approach, 1,344 feet.

46 of south approach, 1,033.

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Force employed in construction during summer of 1858, the working season extending from the middle of May to the middle of November:

Steamboats, 6; horse power, 450

Barges, 72...

Manned by..

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12,000 tons.

500 sailors.

450 men.

2,090 men.

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SYNOPSIS OF PLANS PROPOSED FOR A BRIDGE OVER THE ST. LAWRENCE, AT MONTREAL

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*No plan or estimate-line of soundings taken only.

THE ELECTRIC TELEGRAPH.

THE whole of the telegraphic system of Canada (except the private lines belonging to railway companies) is in the hands of one company.

The Montreal Telegraph Company was organized in 1847, and first opened between Quebec and Toronto. The following figures show the progress of this company:

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The lines enumerated above embrace all the important

towns and villages in both provinces.

There are thirty-two poles to the mile, and the wire is

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