ANNUAL ADDRESS. VII. 



the annual cost to the ratepayer would not be much in excess of 

 the present unsatisfactory system, for the constantly increasing 

 biological knowledge has shown us how the work of dealing with 

 the crude sewage can be satisfactorily and cheaply performed 

 by utilising the means nature has placed at our disposal. 



Among other matters, which, as an Engineer, I hope to see 

 accomplished, is the passing of a satisfactory Local Government 

 Act, and also of an Act dealing with steam boilers, but not, I 

 trust, one to place the inspection in the hands of a Government 

 Department, as proposed in the Bill brought before the Parlia- 

 ment recently. An Act modelled on the English laws would suit 

 all requirements. 



Amongst the works that are in progress the most important is 

 undoubtedly the Sewerage of Sydney which is being carried on 

 by the Departments concerned, the number of houses connected 

 to it being over 50,000, with an estimated population of 250,000. 

 The total cost of the system when completed will, it is stated in 

 the report of the Royal Commission which sat last year, be 

 .£3,463,486, of which the sum of £1,200,000 was unexpended 

 last June. The North Sydney out-fall works at Willoughby Bay 

 are nearly finished, and as they involve several features which 

 have not been used in Australia before, a short description may 

 prove interesting. 



The sewer discharges into screening chambers, in which all the 

 large floating matter will be screened out ; lime will be then 

 added to that portion which passes through the screen and be 

 thoroughly mixed with it, the mixture then flowing into a tank 

 in which to settle and deposit the sludge ; after settlement, the 

 supernatant water will be drawn off by a floating off-take and 

 delivered on to some portion of a large filter bed of about thirteen 

 acres in extent, formed of sand dredged from the harbour and de- 

 posited by the sand-pumps. At a depth of about 4ft., and half a 

 chain apart perforated glazed earthenware pipes have been laid in 

 the sand and connected with a main drain to collect the filtrate and 

 discharge it into the Bay. The trenches in which these pipes are 



