lS5n.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



3G1 



PLATE-IRON GIRDER BRIDGES. 



The annexed engravings show the construction of one of the 

 numerous bridges which have been designed by Mr. Martin, the 

 engineer, to carry the railway from the London and North- 

 M'estern Railway to the East and West India Docks. It carries 

 the railway over Randolph-street, Camden Town. 



The peculiarity consists in constructing the bridge with two 

 side girders, each of a single web, of plates of iron, 71 feet long, 

 (i ft. 7i| inch high, and yV-i"'"!' thick; put together with plates 

 5 inches wide, overlapping the vertical joints, and |-inch rivets 

 placed 3 inches apart, and fixed to the top and bottom plates by 

 angle-iron 3 inches wide, and ^-inch rivets. The bottom plate is 

 a ft. 8 in. wide, made with y^-inch plates in lengths of 8 feet each, 

 with plates overlapping the joints 6 in wide. The outer flange is 

 curved down 1 inch, to throw off tlie wet; the top plate is 2ft. 8 in. 

 girt, made with -fS;-inch plates, excepting tlie tluee middle plates, 

 which are f-inch in thickness; the top is curved down ,5 inches, 

 and put together with inch rivets. The girders are stitfened by 

 eight vertical plates on each side of the web, of ^^inch iron, fixed 

 by angle-iron 3 inches wide, and |-inch rivets placed 4 inches 

 apart. There are also two similar stiffeners at each end, of f-inch 

 iron. The top plate is further stiffened by stays of T-iron, 5^ inch 

 wide between each pair of stiffeners. 



f'g- -.— Side View of Longituiiinal (iinUr. 



The cross girders are 24 ft. 6 in. long and I ft. 4 in. high, made 

 with |-inch plates in three lengths, and stiffened by angle-iron 

 top and bottom and on each side, 3^ inches wide, and fastened with 

 |-inch rivets 4 inches apart. The "ends of these cross girders rest 

 upon the two girders first described. 



Fig. I is a cross section of the bridge. Fig. 2 is a side view of 

 part of one of the longitudinal girders. Fig. 3 is an enlarged sec- 

 tion of one of the girders, showing the stiffeners. Fig. 4 is a section 

 through the same girder, showing the stays to stiffen the top plate. 



THE BRITANNIA BRIDGE. 



The permanent public opening of the new line of tubes for the 

 down line from London to Dublin took place on Monday 21st ult, 

 the great structure being- now in all important respects made 

 complete. On the 19th Oct , Captain Simmons, the Government 

 Inspector, went over it early in the morning, and instituted, in 

 conjunction with the engineers, a long series of experiments. 



The first experiment consisted in passing two locomotive engines 

 through the tube, and resting them at intervals in the centre of 

 the sections. At 9 o'clock a train of 28 wagons and two locomo- 

 tives, with 280 tons of coal, was drawn into all four of the tubes, 

 the deflections being carefully noted. These deflections -were 

 ascertained to be exactly three-fourths of an inch under this load. 

 After repetitions of these experimental ordeals, which occupied 

 several hours, the train of 280 tons, with its two locomotives, was 

 taken out about a mile distant from the tube, and then suddenly 

 shot through it with the greatest attainable rajiidity, and the 

 result was that the deflection at this immense lelocitv of load was 

 sensibly less in the way of undulation than when the load was 

 allowed to remain at rest on the tube. The contrivance by which 



the effects are indicated with great precision consists in a large 

 pipe containing water, laid along the lower cells of the tube, one 

 end rising up within tlie tube at the centre, and the other end 

 fixed against the stonework of the abutments of the bridge. Both 

 extremities of this ))ipe are furnished with glass tubes and gradu- 

 ated scales, by which the relative levels of the water were easily 

 ascertained. As the slightest leakage or evaporation over the 

 ordinary thermometric expansion of tlie water would derange the 

 level, w-hile only half the actual deflection of the tube was regis- 

 tered at each end of the pipe, these disadvantages are obviated by 

 the addition of a large reservoir of water in the interior of the tube, 

 which is covered with oil and jilaced beside the graduated scale. 



Messrs. E. and L. Clark, the resident engineers, who have 

 watched minutely from day to day all the developed peculiarities 

 of the novel undertaking, state that the heaviest gales through 

 the Straits do not produce so much motion over the extent of 

 either tube as the pressure against the side of the tubes of 10 

 men ; and that the pressure of 10 men keeping time with the 

 vibrations produces an oscillation of 1^ inch, the tube itself mak- 

 ing 67 double vibrations per minute. 'Flie strongest gusts of wind 

 that have swept up the Cliannel during the late stormy weather 

 do not cause a vibration of more than a cpiarter of an inch. The 

 broadside of a storm causes an oscillation of less than an inch ; 

 but when the two tubes are braced together by frames, which is 

 now being done, these motions, it is expected, will cease. The 

 action of the sun at midday does not move them more than a 

 quarter or three-eighths of an inch. The daily expansion and 

 contraction of the tube varies from half an inch to three inches, 

 attaining either the maximum or minimum at about 3 o'clock a.m. 

 and p.m. If a compass be held over any part of the bottom of 

 the cells, the south pole is affected, and if held over the top of the 

 cells, the north pole is affected ; and this effect is observable in all 

 parts of the tube, whether at the centre or the end, although their 

 position is only about 10° west of the magnetic meridian. Pre- 

 parations are making for covering the tubes with a light arched 

 roof of peculiar construction. 



GRAND CONTINENTAL CANAL. 



A Belgian engineer, M. de Lavelcye, proposes to connect the 

 Seine and the Rhine by means of a canal. This was one of 

 Cliarleuiagne's ideas — eipially with that connection of the Kbine 

 and the Danube which has been efiected in our own day by means 

 of the Ludwig Canal. The points which M. de Laveleye proposes 

 to connect — Sedan and Trier — are but ninety-five miles asunder, 

 intersected by the rich and populous Grand Duchy of Luxembourg; 

 and presuming the canal to be made, navigation would be open 

 from London to the Black Sea and Constantinople, throuffh the 

 heart of the Continent, and by means of the great watercourses 

 on or near whose hanks lie the materials of nearly all the internal 

 and external trade of Europe. Vessels would ascend the Seine 

 from Havre to the junction of the Oise — they would turn up that 

 river and continue to the .Aisne — there they would again <|iiit tlie 

 main stream and proceed to tlie Ardetmes Canal. At Donchery 

 that canal falls into the Meuse, which is navigable already to 

 Sedan. These rivers and canals are at present connected by 

 trilnitaries and branches witli the whole of north-eastern France, 

 from Rouen to the wine-fields of Champagne, and also with the 

 coal and metallic beds of Belgium. Less than a hundred miles of 

 cutting — but tlirough a district of which we suspect all the 

 engineering difficulties are not fairly stated — -will connect tlus 

 immense net-work of navigation with another still larger and 

 more important — of which the Rhine and the Danube are the 

 main highways — Prussia, Germany, Austria, Huntrary, and the 

 Eastern provinces are the chief features — and the Black Sea and 

 the Mediterranean are the great outlets. The Moselle already 

 reaches the foot of the Ardennes. From it to the .Meuse the 

 distance is what we have stated. From Trier the navigation is 

 open to Coblentz, — the Rhine would carry the vessels up to the 

 Maine, — this river takes them past the trading emporium of 

 Frankfort to the Ludwig Canal, and so into the Danube. On the 

 face of such a project the advantages to France seem to be greater 

 than to any other country — but the subject engages more attention 

 in Vienna than in Paris. Tlie estimated cost is 1,600,000/., — a 

 large sum; but the results are apparently of such magnitude as to 

 insure the execution of the work at some period or other. The 

 whole system of European internal navigation is incomplete so 

 long as the eastern and western branches remain unconnected. — 

 Atltenceum. 



48 



