DISTRIBUTION AND DISTRIBUTORS 303 



the central rotating bucket and the fixed central pillar is made 

 by means of two anti-friction rings and a resilient washer of 

 rubber or corrugated copper. Arrangements are made for an 

 easy inspection of the bearings. The least head desirable is stated 

 to be 4'', and to give three times the dry weather flow a head of 

 28" would be required, unless extra arms are placed at slightly 

 higher levels on the central bucket. For intermittent working 

 an automatic flushing tank is recommended. 



8. Ham and Baker's Revolving Sprinkler at Abbots Langley, 

 near Watford, is illustrated in Fig. 50. 



The Fiddian Automatic Distributor (Birch, Killon and Co.) 

 consists of one or more elongated water wheels 9" to 18'' 

 diameter, which roll bodily over the surface of a filter on 



Fig. 51. — Section of Fiddian Water Wheel. 



circular rail tracks about a central pivot. Each rolling drum 

 has a pipe connecting it to a supply of tank efliuent, which falls 

 into the buckets of the wheel. The water-wheel buckets are 

 divided transversely into sections, each section being supplied 

 from a separate opening in the feed-tube (Fig. 51). The 

 openings are fitted with adjustable weirs of a width propor- 

 tional to their distance from the centre of the filter bed. It is 

 claimed by this system that equal distribution can be obtained 

 without the sewage passing through any restricted areas, or 

 any power other than the head of the sewage itself being 

 utilized. Filters up to 20 ft. diameter have the rolling drum 

 supported on one roller track in addition to the central stand- 

 pipe. A second rolling track is provided when the filter is 

 between 20 and 30 ft. in diameter. A balancing arm or second 

 rolling drum is required when the bed exceeds 30 ft. diameter^ 



