VELOCITY OF FALLING WATER. ibl9 



CHAPTER 11. 



HYDRAULICS. 

 SECTION I. 



VELOCITY OF FALLING WATLR. 



Liquids in motion are subject to the same laws as 

 solids in motion. Falling water increases in velocity 

 at the same rate that the motion of falhng solids is ac- 

 celerated, as already explained under the head of Grav- 

 itation. Thus a perpendicular stream of water de- 

 scends one foot in a quarter of a second, four feet in 

 half a second, nine feet in three fourths of a second, 

 and sixteen feet in one second. Like falhng sohds, 

 the velocity at the end of the first quarter will be eight 

 feet per second ; at the end of the second quarter, six- 

 teen feet per second ; at the end of the thud quarter, 

 twenty-four feet per second ; and at the end of the 

 fourth quarter, thirty-two feet per second. 



Now, if there be an orifice made in the side of a ves- 

 sel of water, the water will spout out with the same 

 swiftness as if it fell perpendicularly from an equal 

 height, were it not retarded a little by friction. For 

 example, if the head of water is one foot above the 

 orifice, the velocity would be at the rate of eight feet 

 per second, but for friction, which reduces it to about 

 five and a half feet* per second. The velocity for any 

 other height of head may be easily found by deduct- 

 ing the same proportionate rate from the velocity of a 



Or, more accurately, 5.4 feet per second. 



