The Scoop Wheel. 87 



water by the outer diameter of the scoops, combined with 

 the gradual contraction of the feeding drain increasing the 

 velocity of the water, the cavities between the scoops are filled 

 from a fourth to a fifth more than the actual dip. The other 

 deduction from the gross power applied for friction of the 

 gearing between the motor and the wheel for the gudgeons 

 and for water lifted too high they consider also as much 

 overrated. Mr. Korevaer, in a paper read before the Dutch 

 Institution of Civil Engineers, gives the useful effect of four 

 scoop wheels and engines in the Netherlands at a mean of' 

 6y per cent, of the indicated horse-power, the greatest being 

 69*6, and the least 60 'O, the lifts varying from 3*66 feet to 

 6-0 feet At Katwijk the percentage varied from 33 to 70 

 according to the height of lift, the mean being 50. At Gouda, 

 with curved scoops, the percentage was 56*3 per cent. ; with 

 the wheels as recently altered to flat scoops, and with new 

 engines an efficiency of 81 '97 per cent was obtained, the lift 

 being 5*80 feet, and the quantity discharged 598 tons per 

 minute. Mr. Huet, in his description of the scoop wheel at 

 Adria, in Italy,* which has a diameter of 39 J feet and width of 

 6J feet, with a lift of from 4 feet to 6 feet, states as the I'esult 

 of working that the proportion of horse-power of water lifted 

 to the indicated horse-power is 72 per cent In the Wexford 

 Harbour trials, when the wheel was first started, the per- 

 centage of useful effect was 68 * 2. 



* * Stoombemaling van Polders en Boezems,' door A. Huet, C.E. Published 

 at The Hague, 1885. The author here acknowledges much valuable information 

 that he has obtained from this work. 



