Drainage hy Steam Power. 



167 



By the above statement a comparison may be instituted be- 

 tween the amount of evaporation and absorption in summer and 

 imnter. 



I have not thought it necessary to give the average depth of 

 water in the wheel-race each month ; but the average up to the 

 19th of February, 1852, was about 1 foot 10^ inches, and the 

 average for the year would be nearly 2 feet. 



As the engine drains 1100 acres, and the amount of rain-fall is 

 35j inches, the total weight of rain for the year on that area 

 would be 3,937,541 tons. From these results it would appear 

 that 66 per cent, of the rain-water was collected by the drains 

 and lifted by the engine, and 34 per cent, was evaporated and ab- 

 sorbed. The average annual evaporation of England for six years 

 ending 1843 has been stated at 57*4. 



Mode adopted in calculating the (Quantity of Water lifted. — 

 Presuming it may be useful to those who are seeking for inform- 

 ation on the subject, the principle adopted in calculating the 

 effective power of the wheel is here given. 



The following are the data: — the speed of the wheel, its width, 

 and the " dip" or depth of the water through which it passes. To 

 show the application of these, let us assume the depth of water 

 to be 2 feet. As the diameter of the wheel is 30 feet, the dia- 

 meter of a circle, the arc of which passes through the centre of 

 the water, will be 28 feet. Then the diameter being 28, the cir- 

 cumference will be (28 X 3-146} = 87*9648 feet; from this 

 deduct 10 feet for the space occupied by the 40 float boards and 

 framing (being 3 inches for each), which will leave in round 

 numbers 78 feet. Next multiply this 78 by the number of revo- 

 lutions per minute (in this instance 4i), and we get 331^ ; which 

 again multiplied by the width of the float boards or scoops — \\ 

 feet (the exact width is 16 inches, but i an inch on each side up 

 to the walls is considered unavailable), makes 414.i ; this, multi- 

 plied by the depth — 2 feet, is 828| nearly — say 829, the number 

 of cubic feet discharged per minute. Then 829 divided by 36 *, 

 gives 23 tons. 



The following table shows the quantity of water discharged by 

 this engine, at different dips : — 



Mr. Boosie's garden at Kulford, which is about 31 feet above the sea. — By the same 

 gauge it was ascertained that the fall of rain for the year 1847 was 38* 54 inches; 

 1848, 45-11; 1849,35-41; 1850, 35-35 ; and 1851, 33-49 ; making an average for 

 the 5 years of 37*54 inches. — The average fall of rain in Deeping Fen, Lincoln- 

 shire, for the 6 years ending 1843, was only about 27 inches, which was the 

 average of England for the same period. 



* This may be taken as the number of cubic feet of water in a ton. A cubic 

 foot of water (1728 inches) weighs 62ilb3. ; the exact weight of 36 feet, therefore, 

 would be 1 ton 10 lbs. ; a gallon of water (2774 inches) weighs 10 lbs., and there 

 are 224 gallons in a ton. 



