Pumping Stations- 115 



level, tlie engine is well above its work, and advantage is taken of 

 the expansion gear, the steam being frequently ciit-ofF at from one- 

 sixteenth to one-tenth of the stroke. Steam is generated in three 

 Lancashire boilers, 24 feet long by 7 feet diameter, the safety-valves 

 of which are adjusted to blow off at 20 lb. The enormous weight of 

 this machinery compared to the work done may be judged from the 

 following : — The wheel alone weighs 75 tons ; the beam of the engine 

 is 3 feet 8 inches deep, and weighs 15 tons ; the fly-wheel is 25 feet 

 diameter and weighs 30 tons. 



The improvements in the engine and wheel resulted in a very 

 considerable saving of coal, the consumption for 1881, before the 

 improvements were made, being 141 1 tons for a running of 2988 

 hours, and an average dip of the scoops of 2' 66 feet as against 691 

 tons for 1883 for 2288 hours' running, and an average dip of 3*30, 

 or, after allowing for the difference in the number of hours' run, this 

 shows a clear saving of 369 tons of coals in one season, while the 

 average extra head pumped against was increased i ' 54 feet, or an 

 increase of work of 31 per cent, and a decrease of coal of 35 per cent. 



A series of trials was made by Messrs. Watt & Co., Birmingham, 

 on January 13th, 1882, after the improvements to the engine and 

 wheel had been completed by them. The following figures give the 

 results of the last of these trials : — 



Mean dip of scoop , .. 4*0 feet. 



Mean lift of scoop 14*79 feet. 



Mean revolutions of engine per minute .. 18 '66. 



Mean revolutions of wheel per minute ., 2* 75. 

 Mean velocity of water flowing down 



engine drain per minute 45 '766 feet. 



Area 137*397 feet. 



Quantity per minute 6288 " 1 1 cub. feet. 



Horse-power, gross indicated 224*05. 



Horse-power, water lifted 1 76 * 1 58. 



Ratio p = -7862. 



Mean circumference of immersed portion 

 of wheel .. .. .. .. 144*5 feet. 



Cubic contents of immersed portion, each 

 revolution less space occupied by scoops 1782' 11 cub. feet. 



Ditto ditto per minute 4900*80 cub. feet. 



The diagram, Fig. 9A, Plate 6, is the mean of those taken for this 

 trial. 



From this it will be seen that the quantity delivered, as measured 



I 2 



