ABSTRACT OF PROCEEDINGS. lxxxi. 



the Alters, the operation of the filters, the bacterial results, 

 the removal of colour, the removal of turbidity, tastes and 

 odours, the removal of coagulant, change in hardness, effect 

 of rate of filtration, and other important matters. 



He then dealt with the cost of mechanical filters and the 

 cost of operation, and he summed up the advantages of the 

 system as follows : — 



(1) Capacity to treat very turbid waters. 



(2) Capacity to remove a very large percentage of colour. 



(3) Occupies a relatively insignificant area of ground. 



(4) Protection from weather. 



(5) Freedom from risks of objectionable growths and from 



tastes and odours they impart. 



(6) Rapidly and easily cleaned, without risk of contamin- 



ation by workmen. 



(7) Sand bed can be easily and economically sterilized. 



(8) Absolute control of each separate filter, together 



with complete knowledge of its condition. 



(9) Allows water to be sent straight to the consumer with 



the least possible delay and expense. 



In an appendix the author gave certain rules and regu- 

 lations to be observed in judging the quality of a filtered 

 surface water. 



Mr. J. B. Henson, Assoc, m. inst. c.b. read a paper on " Fil- 

 tration as carried out on the Hunter River at West Mait- 

 land." 



He first of all described the watershed of the supply and 

 the nature of the water, giving comparative analyses of 

 the solids in solution. The author said that the present 

 arrangements for filtering the water are as follows : — A 

 settling tank into which the water to be filtered is delivered 

 from the pumps ; four filter beds at a lower level, each 

 100 feet square, and a clear water tank. 



/—Dec. 7, 1904. 



