644 PROCEEDINGS OF SECTION J. 



rising to the higher levels, also with flushing and penstock 

 chambers. Three million biicks and thirty-five thousand casks of 

 cement were used. 



From the main sewer branches have been laid along Nobbs, 

 Arthur, and Phillip-streets, and to these branches the City Council 

 have connected a series of subsidary pipe sewers which are laid on 

 the most approved system in straight lines, with lamp-holes, pro- 

 vided with dirt boxes and moveable gratings, the whole system 

 being so constructed that it can be examined from time to time 

 without disturbing the road. Complete arrangements have also 

 been made for flushing by means of valve chambers and automatic 

 syphons at the head of the pipe sewers ; but, at present and until 

 the city water is fully available, fresh water will be used from the 

 adjacent water mains, conveyed to the lamp-holes or dead ends by 

 means of a hose. 



OUTLET-HOUSE AND STRAINING CHAMBER. 



The inlet-house receives the sewage from the main outfall sewer, 

 where it is made to pass through three sets of circular screens 

 which can be revolved by means of gearing worked by hand. The 

 screens intercept extraneous matter, such as heavy road detritus 

 and sand, which it would not be advisable to admit into the syphon; 

 it is therefore dredged out and conveyed to the sewage farm by 

 means of trucks drawn by a six-ton locomotive over a timber bridge 

 constructed (with a swing opening or lift) immediately over the 

 syphon. The screening apparatus is in duplicate, so that one set 

 is in operation while the material is being dredged from the other. 

 The sewage, after passing through the screening chambers, flows 

 into a chamber or sand-basin, where a further deposition of sus- 

 pended matter, such as fine sand, takes place. This chamber is 

 separated from the syphon well by means of a curved weir, over 

 which the sewage falls into the well and from thence to the sewage 

 farm. The sewage in the sand basin is raised when necessary by 

 means of a small ejector, so that every drop of sewage is passed 

 to the farm. The syphon is one thousand and ninety-two feet 

 long, with grades of one in sixteen and one in eight hundred ; the 

 hydraulic grade is one in one thousand one hundred and two, and 

 consists of cast-iron pipes three feet nine inches in diameter sur- 

 rounded with concrete. The syphon delivers the sewage into an 

 inlet-house, built on the south side of the river, from which the 

 sewage passes along an open channel or main carrier, which is 

 supported by means of concrete arches over the low-lying ground, 

 and on a continuous concrete foundation on the higher ground. 

 The main carrier is constructed with concrete six feet nine inches 

 deep by four feet wide, with sides sloping one in eight on a gradient 

 of three feet per mile. It is rendered inside with cement mortar 

 of similar proportions to those used in the main sewer. The 

 carrier is provided with stop-boards, grooves and valves on each 



