598 PROCEEDINGS OP SECTION J. 



girders. Two winches, resting on platforms secured to each pier 

 convey the power necessary to raise the bridge. The towers, formed 

 of angle irons and plates braced with T-irons and flat bars,. 

 are connected longitudinally with overhead girders. Bevel 

 gearing to ensure uniformity of motion connects chain wheels at 

 top of towers. Two men can lift the main span through nine- 

 teen feet in three minutes. The piers are formed of wrought and 

 cast-iron cylinders, four feet six inches diameter, sixteen feet 

 centres, based with wrought-iron diaphragm bracing. The bridge 

 was designed in 1885. Lift bridges of the same type, with iron 

 approach spans, were constructed at Bourke in 1877, and Bal- 

 ranald in 1878, whilst a contract for a modified design, working 

 wire rope in place of chains, has recently been let for the Murray 

 River and Mulwala. 



PUNTS AND PERRIES. 



The total number of ferries provided for by the Roads Depart- 

 ment is one hundred and thirty-seven ; eighty-five of these are 

 worked by punts, with hand gearing and wire rope of a total 

 length of eleven and a half miles ; six punts are worked by steam 

 and wire rope ; fifty-two crossings ai'e supplied with passenger 

 boats only, eighteen of them being of iron, for occasional use 

 during flood time, as it was found that in the hot months the 

 timber boats were useless when most required. All the punts are 

 built of timber, except seven, which are of iron. The old system 

 of chain and gearing has been replaced by galvanised crucible 

 steel wire rope of a strength of eighty tons per square inch. 

 These steel ropes last from nine to twelve months, working con- 

 stantly fifteen hours a day for seven days a week. The commonest 

 kind of indiarubber is found to be the best lining for the driving 

 wheels, and gives quite suflicient grip on the rope. The sizes of 

 ropes used are two and a-quarter inches circumference for hand- 

 worked ferries, and two and a-half inches circumference for steam 

 ferries. In most cases the ferries are leased for a term of yeai's, 

 but all the steam ferries are worked by the Department. 



CARRIAGE WAYS. 



The older streets of Sydney were originally roughly formed 

 over the routes of the bullock drays, and as buildings sprang up 

 these tracks were first ballasted with sandstone, and ultimately 

 metalled with broken ballast, but they remained very convex in 

 shape and difiicult to maintain. As the traffic developed with 

 the growth of the city, increasing renewals and reconstructions 

 became necessary, in spite of which the cost of maintenance in 

 the principal thoroughfares rapidly increased. The streets with 

 light traflic were reconstructed with satisfactory results in the 

 following manner : — A solid foundation, consisting of hand- 

 packed hammer-dressed sandstone pitchers, ten inches deep, was 

 laid and covered with a layer of broken basalt two and a-half inch 



