VOL. LI.3 PHILOSOPHICAL TRANSACTIONS. 343 



thereby raised in the head ; which being of a regular figure was easily measured. 

 The sluice by which the water was drawn upon the wheel, was made to stop at 

 certain heights by a peg ; so that when the peg was in the same hole, the aper- 

 ture for the effluent water was the same. Hence the quantity of water expended 

 by any given head, and opening of the sluice, may be obtained : for by observ- 

 ing how many strokes a minute was sufficient to keep up the surface of the 

 water at the given height, and multiplying the number of strokes by the value 

 of each, the water expended by any given aperture and head in a given time 

 will be given. 



These things will be further illustrated by going over the calculus of one set 

 of experiments. 



Specimen of a Set of Experiments, 

 The sluice drawn to the 1st hole. 



The water above the floor of the sluice 30 Inches. 



Strokes of the pump in a minute. 394- 



The head raised by 1 2 strokes 21 



The wheel raised the empty scale, and made turns in a minute 80 



With a counter-weight of 1 lb. 8 oz. it made 85 



Ditto tried with water. 86 



N* Weight. Turns in a min. Product. 



lb. ttz. 



1 4 45 180 



2 5 42 210 



3 6 36^ 2171 



4 7 331 236| 



5 8 30 240 maximum. 



6 9 26^ 238J 



7 10 22 220 



8 11 l6| 181^ 



9 12 * ceased working. 



Counter-weight for 30 turns without water, 2 oz. in the scale. 

 N. B. The area of the head was 105.8 square inches. 

 Weight of the empty scale and pulley, 10 oz. 

 Circumference of the cylinder, 9 inches. 

 Circumference of the water-wheel, 75 ditto. 



Reduction of the above Set of Eodperiments, 

 The circumference of the wheel 75 inches, multiplied by 86 turns, gives 6450 

 inches for the velocity of the water in a minute ; -^ of which will be the velocity 



• N. B. When the wheel moves so slow as not to rid the water so fast as supplied by the sluice, 

 the accumulated water falls back upon the aperture, and the wheel immediately ceaseg moring. — Orig. 



