sot 



quired the time of the water's oscillating in either of the legs from tire 

 lowest to the highest points. 

 Let L = length of the whole canal, g = 32% feet ; thea 



W- 



gX (sin. 0+ sin. 6')' 

 "When the two ascending tubes are vertical, 



Cor. Hence if the legs are vertical, the time of one oscillation = th 

 time in which a pendulum would vibrate, whose length is L. 



2. The vibratory motion of water in the form of waves may be com- 

 pared to the above reciprocation in a siphon or bent tube. And hence if 

 a be the altitude of a wave, and b half the breadth, the time of one undu- 

 lation, i.e. the time, from the wave being highest at any point, to its 

 being highest at that point again, is 



and the space which the wave appears to pass over in a second is 

 b 



Cor. 1. If a be neglected, the velocity of the wave becomes * g , 

 which is the velocity as determined by Newton, Princip. lib. 2. Prop. 46. 



Cor. 2. Hence a pendulum whose length = its distance between any 

 two consecutive highest and lowest points will make two vibration* 

 during the time of one complete undulation ; or if the pendulum is four 

 times the preceding, i.e. equal to the distance of any two consecutive 

 waves, the time of one undulation equals the time in which this latter 

 pendulum would perform one vibration. 



SLUICES. See fluids. 



SOLAR inequality. See Precestion. 



SOLAR mean time. See Time. 



206 



