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HYDRAULICS. 



Hydraulics is the science which teaches us how 

 to estimate the swiftness and force of fluids in 

 motion, and upon these principles many machines 

 worked by water are constructed. 



When an open vessel full of liquor is pierced at 

 the bottom, the liquor spouts out with great force; 

 but as it continues to run, it flows more feebly. 



If a hole be made in the side of a vessel, the 

 water will spout out horizontally, because fluids 

 press equally in all directions. 



The velocity with which water spouts out at a 

 hole in the side or bottom of a vessel, is as the 

 square root of the depth or distance of the hole 

 below the surface of the water : for, in order to 

 make double the quantity of a fluid run through 

 one hole as through another of the same size, it 

 w r ill require four times the pressure of the other, 

 and, therefore, the aperture must be four times the 

 depth of the other below the surface of the water; 

 and for the same reason, three times the quantity 

 running in an equal time through the same sort of 

 hole, must run with three times the velocity, which 

 will require nine times the pressure, and conse- 

 quently the hole must be nine times as deep below 

 the surface of the fluid, and so on. 



