XXX. J. DAVIS. 



By this means the water is turned off or on when the machinery- 

 stops or starts. 



STORAGE BATTERY. 



A storage battery has been installed, consisting of 230 Epstein 

 cells. The primary duty of this is to provide power to run the 

 plant at night when the tramway plant is not available, and, 

 in the second place, during ordinary running to reduce the drop 

 in the line between Rushcutter's Bay and Double Bay. 



The battery is always switched on, so that when the machinery 

 is running the motors obtain their energy partly from that and 

 partly from the line. As soon as the motors are stopped the 

 batteries start charging, making up for what has been used whilst 

 running. In addition to the advantages derived in this way 

 from the battery, it was possible to materially reduce the area 

 of the cable. 



SWITCH BOARD. 



A switch board is provided with all the necessary fittings, 

 including recording ammeter, voltmeter with connection to line 

 or battery, ammeter to each motor, polarised battery ammeter, 

 and all the necessary quick break switches, polarised battery, 

 cut out plug fuses, and electric light circuit connections. 



QUANTITY TO BE PUMPED. 



Taking the average annual rainfall at 51*522 inches, the 

 quantity of sewage and rainfall to be pumped would amount to 

 54,846,137 gallons per annum, and the h.p. hours expended, 

 taking the efficiency of the whole plant as 34*8 per cent., would 

 be 35,371. The cost of electrical energy would therefore be 

 £147 7s. 6d. per annum, and the cost (including energy, wages, 

 and 6 per cent, per annum on capital cost for repairs and 

 renewals) of lifting 1,000 gallons would amount to 5*688 pence 

 with present population, and 3*991 pence with future population. 



EFFICIENCY TESTS OF PLANTS. 



In order to obtain efficiencies of the plant, tests were made 

 under ordinary working conditions on February 13th, 14th, 15th 

 and 16th, with one air compressor and all the ejector stations 

 working. 



