1918] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



35 



The great height and length of this bridge, and the extreme 

 lightness of its construction, render it an imposing object, spanning 

 a beautiful and thickly wooded ravine near Dalkeith Palace, with 

 the river Esk streaming through it, and appearing as a mere line 

 of water in passing under the centre arch, which is the largest and 

 highest. 



The system of arching with planks, may be carried to almost any 

 extent, and in Messrs. Green's design for the proposed bridge 

 across the Tyne, to connect the towns of Newcastle and Gateshead, 

 at a high level, the largest arch over the middle part of the river 

 was intended to have been 280 feet span, with a versed sine of 70 

 feet, the total length of the bridge as designed was 1,220 feet, and 

 the height 1 10 feet. 



Fig. 1. 



The annexed wood engravings show an oblique bridge on the 

 Newcastle and North Shields Railway, crossing the Shields road, 

 at Walker. The angle of the skew is 25°, and the span is 71 feet. 

 Fig. 1 is an external elevation of one of the ribs and the piers, and 



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Fig 2. 



iig. 2, a plan of the joisting and piers. The joists of the platform 

 rest upon the longitudinal beams, which are suspended by queen 

 posts and iron straps, from two arched ribs, one on each side of 

 the railway, and stiifened by struts and braces. The ribs are formed 

 of de lis 11 inches by 3 inches, dressed one deal and a half for the 

 width of the rib, and nine deals in depth, as shown in figs. 3 and 4. 



Fig. 3. 



Th«y spring from cast-iron sockets, bolted to the ends of the longi- 

 tudinal beams, on which they abut. An iron strap is also keyed 

 over eacli foot of the ribs, for additional security. The width for 



the railway on the bridge is 21 feet 6 inches. In the centre, at in- 

 tervals of about 7 feet, the platform is strengthened by 

 trusses, which are marked h b, fig. 2, and constriicted in 

 the manner sliown in fig. 4-, with wrought-iron bars keyed 

 at the ends of the l)eams, and coming underneath, hav- 

 ing three iron bearers in the full length. The cost of 

 this bridge was about 1,300/. 



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Fig. 4. 



The DiNTiNo Vale Viaduct, oj) the line of the Sheffield anrf Man- 

 chester Railuiiy. By Alfred Stanistreet Jee, M. Inst. C.E 

 (With an Engraving, Plate IK J 



This viaduct consists of sixteen arches, five of which are of tim- 

 ber and eleven of brick, faced with stone quoins. The whole of 

 the large piers, wings, outside spandrils and parapets, are of ashlar 

 stone, of excellent quality, from the quarries in the neighbour- 

 hood. The foundations of some of the piers are laid upon the hard 

 shale, and of others upon a bed of wet sand of considerable depth ; 

 in the latter cases masses of concrete were formed to receive the 

 masonry. Several of the smaller piers are founded upon the marl ; 

 also with beds of concrete beneath them. The piers for the large 

 arches are built solid, up to the surface of the ground, and above 

 that le\el they are hollow, nearly up to the impost ; the hollow 

 portion having an inverted arch at the bottom, and being also 

 arched over at the top. The iiortion above the impost in the 

 large piers is solid to the top, (see fig. 3.) The smaller piers are 

 cased with ashlar on the outside, and are filled in solid with good 

 flat-bedded rubble, well grouted, and with through stones at inter- 

 vals of 6 feet horizontally in each course. 



The smaller semicircular arches of brick, at each end of the 

 viaduct, are 50 feet in the span and 3 feet in thickness, 

 with stone quoins, and are built in a curve ot 40 chains radius'. 

 The face of each ])ier is parallel to that of the next, the 

 piers themselves being wedge-shaped, on account of the curve. 

 The abutments between the large and the small arches are hollow 

 and are arched over in the interior, to carry the roadway. The 

 abutments and wings at each end of the viaduct, are also 'hollow, 

 being com))Osed of longitudinal and cross walls, flagged over on 

 the top. They are surrounded on the outside by the slope of the 

 embankment, the material of which being clay, is kept out by a 

 wall at the ends. 



The five large arches are each 125 feet span and 25 feet versed 

 sine, of the best Memel timber, tlie whole of which has been im- 

 mersed in a solution of the sulphate of copper, according to Dr. 

 Margary's patent, for the prevention of decay. There are four 

 main ribs in each arch, composed of planking 3 inches thick, laid 

 longitudinally, with a layer of brown paper and tar between the 

 planks, which are fastened together with oak trenails at intervals 

 of 4 feet. These ribs are 4 feet 6 inches deep, and 18 inches wide, 

 and are firmly stayed by diagonal and cross braces, screwed up 

 tight, by means of wrought-iron rods, 2 inches in diameter, passing 

 through and secured by nuts on the outside. The uprights and 

 diagonals in the spandrils are also stayed by iron rods, and are 

 morticed into the longitudinal beams which carry the cross joist- 

 ing. These longitudinal beams are fastened down upon the piers 

 by iron bolts, let 12 feet into the solid stonework, to resist any 

 tendency of the arch to rise in the haunches, when the weight of a 

 train comes upon the centre. The cross joists are placed 5 feet 

 apart, from centre to centre, and are bolted to the longitudinal 

 beams underneath. Upon them is placed longitudinally a half balk 

 of timber, to which the rails and chairs are fastened, and also a 

 guard rail to prevent tlie carriages getting off the road. The whole 

 is covered over with planking 3 inches thick, and is coated with a 

 mixture of lime, ashes, and sharp sand, which has set hard and 

 does not crack. 



The centering used for turning of the arches is of iron, of light 

 construction, and is shown in fig. 1. 



The total length of the viaduct is 484 yards, and its greatest 



