230 



the Dominion Bridge Company at Quebec. The total cost was 

 £110,000. 



LACHIKE BRIDGE. 



The Lachine Bridge is on the Canadian Pacific Railway, and 

 has 20 spans of 242 feet. They are simple truss girders, car- 

 rying the rails on the top, except on the two channel spans, 

 where the rails run between the girders. The cost is £250,000. 



SIIKKAR BRIDGE. 



The Sukkar Bridge is built across the Indus and has a canti- 

 lever span of 790 feet in the clear, the clear centre span being 

 200 feet ; the height of the cantilever is 40 feet, and it is sup- 

 ported with trussed iron guys 280 and 300 feet long respec- 

 tively. The width of the members at the bed-plates is 100 feet, 

 and at the cantilever ends and centre of back guys 20 feet wide. 

 It is built of steel, and for a single track, and will weigh, 

 exclusive of the clear centre 200 feet span, 3,000 tons. It was 

 designed by Mr. Bendel and built by "Westwood, Bailie, & Co., 

 of Poplar, England. I am unable to state the cost, but the 

 coffer dams cost £1,635, and the erection of the ironwork 

 £4,354. 



HAWKESBURY BRIDGE. 



The Hawkesbury Bridge is to be built across the River 

 Hawkesbury, in TsTew South Wales, near its discharge into 

 Broken Bay. It is to be 2,896 feet long, in five spans of 416 

 feet each and two spans of 408 feet each. The width will be 

 28 feet centre to centre of trusses. The total height from the 

 bottom of the piers to the rail level will be 227 feet, the rail 

 level being 42 feet above high water ; the piers have to be sunk 

 185 feet. The sinking of the piers, which will be of wrought 

 iron filled with cement concrete up to low-water level, will be 

 watched with much interest. The piers are all oval in shape, 

 being 20 feet wide and 48 feet long, of three-eighths inch 

 boiler plate. "Within this large tube three cylindrical tubes 

 will be placed, and joined to the outer shell by bell-mouthed 

 connections. These inner tubes are to be used for dredging 

 the contents of the large tube, and by this means allowing it 

 to sink to the required depth. The contract price for delivery 

 and erection is £327,000, and the work is let to the Union 

 Bridge Company, of New York, and a large portion of the 

 ironwork is being executed in Glasgow. 



IRON AND STEEL. 



The question of Bridge construction leads me to touch upon 

 the relative values of iron and steel for such purposes. In 

 looking at these values, I find that in a paper read in August, 

 1885, Mr. Jeremiah Head, the President of the Inst. Mech. 



