390 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[December, 



the place, little more is required than to fix the finished mate- 

 rials in the positions intended for tliem. The lenirth of sash- 

 I>ar is stated liy Mr. Paxton at 20.5 miles. The quantity of glass is 

 about 90(),(KK) feet, weiijhing too tons. 



On eacli of tlie longitudinal «-rouglit-iron framed girders is laid 

 a gutter, and upon and coniniuuii'ating with this, four transverse 

 gutters and plates, on whicli are l.iid the saslil)ars of the fourridge- 

 and-furrow roofs and glazing. The water falling on the glass is 

 carried to the transverse gutters in the furrows, tlience to the 

 longitudinal gutters on the girders, and so down the hollow columns 

 of the building to the bases, whence it is carried o6f by 6-inch 

 cast-iron water pipes. 



The glass made use of is English crown, jO inches Ions, 10 inches 

 wide, and yij-inch thick, running from the ridge-piece to the 

 gutter-plate. The object of this length is to do away with overlaps. 



The transverse trussed gutter -plates or troughs are cut out ot 

 solid fir-scantling by machinery before they are brought on to the 

 building. These transverse gutter-plates are trussed v.ith wrought- 

 irun rods, bent in the form shown, which can be screwed up or 

 slackened by nuts at the end. 



Havinjj: explained the general construction, we shall now refer to 

 our engravings. Fig. 1 is half-length of the transverse gutter- 

 ))late A, the whole length being 2+ feet, widtli 5 inches, and depth 

 fi inclies. On the lower part of the gutter-plate is seen the tension 

 rod, c, 1 inch in diameter, secured by a nut and screw-plate at a, 

 and passing through the eye of the queen bolts, h. It is particu- 

 larly worthy of observation that the gutter-plates are made with a 

 camber, so that the rainwater shall fall from the middle of the 

 gutter to the ends, be readily carried off, and be precluded from 

 lodging. The but-ends of the gutter-plates, as shown in fig. 2, are 

 likewise brought together, and fixed in a cast-iron shoe, with an 

 aperture to carry the water down into a square trough. 



Figs. 2, 3, 4-,' and 5, are enlarged views of the gutter-plate, 

 drawn to a scale of one-fourth the full size. Fig. 2 is a side view, 

 bowing the ends of the tension rods with the nut and screw, and 

 cast-iron plate fixed to the underside of the gutter-plate, of which 

 fig. l is a view of the underside, and fig. 5 a transverse section of 

 the gutter, showing the end of the tension rod, and how the plate 

 is fastened to the timber. 



Fig. 3 is another transverse section of the gutter at //, s, and also 

 of the skylight, showing the wooden bar of the skylight and the 

 ridge. The ridge is worked by macliinery out of solid deal 3 

 inches square, and the butting-joints have ^-inch dowel 3 inches 

 long. The ordinary skylight-bars are Ij inch deep by 1 inch 

 wide, shown in the small section, with a ^--inch groove on each 

 side to receive the glass. The other small section shows the form 

 of other intermediate-skylight bars called string-bars, which are 

 2,' inches wide by 1^ inch deep. It will be perceived by the 

 section, that the skylight-bars frame into the ridge, and are 

 notched on to the trough gutter, being secured at top and bottom 

 by 3-inch nails. For the purpose of taking off any condensation 

 fm'ming within the building which may run down the glass, a 

 groove is provided worked on eacli side of the gutters. 



'I'he skylights are H feet span, and have an incline of 24 to 1. 

 Fig. () is a transverse view of one of the ridge-and-furrow 

 skylights. 



Figs. 7 and 8, elevations of the exterior, showing the two stories, 

 the lower being closed with boarding, and tlie upjier glazed. The 

 base, to the height of -t feet, is fitted with lufi'er boarding, with 

 the view to ventilation. 



If the several details be carefully examined, it will he discovered 

 there are several contrivances to save labour and facilitate fixing. 

 It vvill be interesting to observe, that in matters so common and so 

 c<inimonplace, there was yet room for the exercise of research and 

 ingenuity. 



TIIF lUlIDGE FAILURE AT THE SOUTH-EASTERN 

 STATION, LONDON HRIDGE. 



Experience is only true and valuable so far as it is on an 

 extended basis, for though called so, that is not experience which 

 is merely local and partial. We are not always called upon to 

 reproduce the same model or work on the same lines; but our 

 practice is chiefly in the extension or particular application of 

 existing examples. It therefore becomes of tiie greatest import- 

 ance that we should have as wide a c(d!ection of facts as pos- 

 sible, so as to enal)le us nu)re safely to calculate the result of any 

 new direction, new application, or further extension; so, indeed, 

 as to secure us from experimenting too far. We want, tlierefore, 



not only examples of success, but of failure; we want especially 

 to know where any princijile has been strained too much, that we 

 may avoid such extreme, and where any detail has proved de- 

 fective, so that we may apply the proper remedy. It has there- 

 fore always been considered, by our best authorities, as most ex- 

 pedient to record failures. Thus Smeaton prefaces the history of 

 the Eddystone Lighthouse; thus, in the history of the Menai 

 Bridge, the checks received in experimenting, by which the ulti- 

 mate application was arrived at, are carefully set forth for the 

 guidance of future practitioners. ^Ye have therefore felt it highly 

 desirable to report, as accurately as it is possible, a few parti- 

 culars as to the failure of the Bridge over Joiner-street, at the 

 carriage entrance to the South-Eastern Railway Offices of the 

 London Bridge Station, which took place on the IQth October last. 



The bridge is of a peculiar construction, and consists of six 

 compound girders of cast and wrought iron, patented by Captain 

 Warren. The annexed engraving, fig. 1, shows part of one of the 

 girders, rather more than half the length; and fig. 2, a transverse 

 .section of the roadway and two of the girders. There are in all 

 six girder.s, placed lift. 6 in. apart. The girder that broke is 

 41ft. 6 in. long, and consists of a series of triplet cast-iron tri- 

 angles, with a connecting-rib along the top and bolted at the 

 joints, hut there is no connecting-rib along the bottom of the 

 girder; instead of which, they are held together by a horizontal 

 tie, consisting in width of four wrought-iron bars, 6 inches deep 

 by Ij inch thick and 13 feet in length, coupled together by 4A 

 inch bolts passing through a boss cast on the triangular stays, and 

 also bolted to the intermediate triangles. 



The cast-iron triangles are 4 feet deep, with a rib cast on the top 

 6 inches deep, making the whole height of the girder 4 ft. (i in., 

 and the length of the triplets 13 feet; the section of the cast-iron 

 is T-shaped, 5^ inches wide on the back, and the depth the same; 

 the thickness of metal 2 inches. 



On the top of the girders are laid cast-iron plates, U ft. 6 in. 

 long, with ribs bearing at each end on the girders; on these plates 

 rest the materials which form the road, as shown in fig. 2. It 

 must be observed, that the horizontal tie-bars are not intended to 

 act iis suspension bars; they are merely connected at the abutment 

 piers to the ends of the cast-iron triangles. The points at which 

 the bridge failed is marked with the lettery^ where one of the cast- 

 iron stays broke asunder, and also the top rib, as shown in fig. 3, 

 which is an enlarged view of the triangle which failed. It was 

 only 5 feet from the abutment. The fracture is shown »tf,f,f. 



Various statements have been made as to the cause of the failure. 

 It was stated that the accident was caused by the girder being 

 loaded with a large stack of bricks; but tliis is doubted, as the 

 stack was at the opposite end, as shown in the annexed diagram. 



The stack of bricks bearing on the girder was 11 feet square and 

 5 ft. 6 in. high, equal to 066 cubic feet, which will give, at 72 feet 

 to the thousand, between nine and ten thousand bricks, or a weight 

 of about 22 tons. Another statement is, that tlie failure was 

 caused by two carts which were on the bridge at the time ; one of 

 them, loaded with bricks, it is supposed passed over some obstacle, 

 and caused the wheel to descend suddenly with great force. AVhe- 

 ther this be so or not, we cannot pretend to say; but if the bridge 

 had been properly constructed, with a cast-iron girder 41 ft. 6 in. 

 long, and of the great depth of 4 ft. 6 in., it ought not to have 

 broken down with any such force. For ourselves, we are decidedly 

 averse to these compound girders of wrought and cast iron. The 

 contraction and expansion are unecpial; and, consequently, the 

 strain must be constantly varying, while the slightest deflection of 

 the wrought-iron must cause the cast-iron to snap asunder. 



If this bridge had been constructed with a series of triangles, 

 cast with a connectini':-rib at the bottom and a broad flange on the 

 underside ecpial in weight to the wrought-iron, it wouiil, in our 

 opinion, have stood, and borne a weight far greater than this com- 

 pound-girder bridge. 



The broken rib having been made good, the bridge has been 

 tested with a considerable weight, but with what success we have 

 not been able to ascertain. 



Figs. 1 and 2 are drawn to a scale of ^-inch to a foot, and fig. 3 

 to a scale of j-iuch to a foot. 



