NORTH SYDNEY AND DOUBLE BAY SEWERAGE SCHEMES. XIX. 



presses. Lime is again supplied in a suitable proportion to 

 facilitate the pressing of the cake. 



Near the sludge receivers, and of similar construction and 

 capacity, is a third cylinder for compressed air, which is supplied 

 from the air compressor at a pressure which for all ordinary 

 requirements averages about 80 lbs. per square inch. 



When the sludge receiver is filled, the sludge supply is closed 

 and an inlet valve from the air cylinder is opened. The com- 

 pressed air exerts a downward pressure on the surface of 

 the sludge, forcing it through a deep pipe which passes up to 

 one or other of the filter presses on the upper floor of the 

 building. 



The filter presses were manufactured by Messrs. Manlove, 

 Alliott & Co., of Nottingham, and specially designed for these 

 works. Each press consists of a series of rectangular cast iron 

 plates, each 3 ft. 2 in. square, vertically hanging between and 

 bearing upon the sides of a strong frame in such a way that 

 they can be moved together or apart. Each plate is cast with a 

 4 in. diameter hole in the centre. At one end of the frame a 

 strong cast iron cylinder is attached into whicli compressed air 

 can be admitted with the effect of actuating the headstock that 

 bears against the series of plates. To prepare the plates for use 

 each is tightly sewn up in filter cloth, leaving the hole in the 

 centre open. 



A small quantity of slack coal is used to start the combustion 

 in the destructors. After a fair start, owing to the greasy nature 

 of the cake (with the coke breeze mixed with it after leaving the 

 press), it burns quite freely, producing a hard clinker quite 

 devoid of the slightest odour. 



Steam injectors fed from the boiler are provided to increase 

 the draught in the destructors. The fumes pass round the boiler 

 and over the fire grate before finding their way to a chimney 

 stack 80 ft. in height. 



The amount of sludge produced by precipitation, with the 

 present population, would, if the area were all sewered, be about 



