OF A BALL BY A JET OF WATER. 



285 



The apparatus employed in these experiments consisted 

 of a wheel three inches in diameter and half an inch broad 

 at the rim^ made of painted wood, capable of turning very 

 freely about its axis^ and suspended by 

 two wires, with its axis horizontal, so 

 that it could swing like a pendulum. A 

 vertical jet of water was so arranged 

 that it could be made to strike the reel 

 at any point from below, or to miss it 

 altogether. This was done by bringing 

 the jet out of a horizontal pipe which 

 would slide backwards and forwards in 

 the same direction as the wheel could 

 swing. This pipe was furnished with 

 a cock, so that the force of the jet might be altered. 



In experiment No. i, the pipe from which the jet issued 

 was pushed so forward that the jet missed the reel by about 

 an inch, and the jet was turned on to rise about six feet 

 above the reel; the pipe was then brought back until 

 the water passed as near as possible to the reel without 

 touching it — but there was no apparent effect produced 

 on the reel. The tap was turned so as to increase and 

 then diminish the height to which the jet rose — still, with- 

 out any effect. 



Experiment No. 2 was made with the same apparatus as 

 No. I . The reel was then changed for one six inches in 

 diameter, and the same experiment repeated. 



The jet was placed so that it missed the reel (when 

 hanging freely) by about two inches, and the water was 

 turned on to rise about six feet. The reel was then pushed 

 forward until it touched the jet and then let go; it imme- 

 diately began to turn about its axis, but left the jet, swing- 

 ing backwards and forwards, touching the jet each time, 

 and each time gaining in speed of rotation. This went on 

 for several oscillations ; but as it got to turn faster, it ap- 



