614 PROCEEDINGS OF SECTION J, 



consists of four openings sixty feet in the clear formed with two 

 main girders two hundred and forty feet long over all and seven 

 feet deep, each continuous over three piers, and in other respects 

 similar to the bridges over Orimbah and other creeks referred to. 

 The bridge over Dora Creek consists of seven openings, each sixty 

 feet in the clear, formed with two main girders, each continuous 

 over two piers, and also two main girders, each continuous over 

 three piers ; in other respects the bridge is similar to those last 

 described. As only one pair of rails was laid over these bridges 

 when they were tested by the Engineer-in-Chief, the maximum 

 load which could be put upon one girder was .71 tons per foot run, 

 and the maximum deflection observed with this load during the 

 testing of all the bridges was .23 inches. A series of timber 

 openings occur in this line, just beyond Gosford, twenty -six feet 

 and ten feet in the clear, similar in construction to those on 

 Southern and Western lines. 



On the line from Newcastle to Tenterfield the first work of im- 

 portance is the bridge over the Hunter, at Singleton, forty -nine and 

 a-half miles from Newcastle, which consists of five timlaer-arched 

 openings each eighty feet in the clear, and two masonry arches 

 fifteen feet span. The piers and abutments are built in masonry set 

 in Portland cement. Each eighty feet span consists of four lami- 

 nated timber arches under the railway, having a rise of twelve feet 

 three inches ; they are formed of planks three inches inthickness and 

 bent by steaming and fastened together by wrought-iron bolts. 

 The main ribs are three feet deep at the springing, diminishing to 

 two feet at the crown of the arch, and are fifteen inches thick. 

 Resting on theop tof each arch is a longitudinal beam of ironbark 

 timber, twelve inches by twelve inches, extending the full length of 

 the bridge, supported over the spandrails by open timber-bracing. 

 Joists ten inches by seven inches and thirty feet long are laid across 

 the roadway three feet apart from centre to centre, and covered with 

 three inch planking throughout the full length of the bridge. The 

 width between the parapets is twenty -seven feet six inches. 



A bridge over the River Hunter at Aberdeen, eighty-eight miles 

 from Newcastle, erected in 1871, is of the same construction as the 

 lattice-girder bridge over the River Macquarie at Bathurst and 

 Wellington, with the exception of the depths of the cylinders, 

 which for this bridge are sunk an average depth of twenty feet 

 below the ordinary level of the water in the river. The testing 

 of this bridge with a load equivalent to 1.37 ton per foot gave a 

 maximum deflection of .92 inches in the side spans and .89 in 

 the middle span. The tunnel through the Liverpool Range, 

 one hundred and twenty-six miles from Sydney, is five hundred 

 and twenty-eight yards in length, and is lined throughout with 

 brickwork set in Portland cement. It is of the same dimen- 

 sions and form as the tunnels previously described. 



