MECHANICS 



one of them the fluid in the whole of them will settle 

 itself at one and the same level, or, as is commonly said, 

 " water will always find its own level." 



It has been said that liquids transmit pressure, not 

 only in the direction opposite to that in which it is 

 applied, but equally in all directions; thus a hollow 

 vessel may be filled with water, which it will hold quite 

 securely. But if a long tube be screwed into the top of 

 it and filled with water, it will cause the so-filled vessel 

 to burst, if the tube and column of water be sufficiently 



FIG. 14. 



ii q? ir e 



high ; and it makes no difference whether the tube be 

 stout or slender. 



Therefore the weight of even half an ounce of water 

 will burst any vessel, if the tube and column of water 

 are only high enough ; for on account of the equality of 

 pressure in all directions, a pressure equal to the whole 

 weight of the entire column will be exerted on every 

 part of the inner surface of the hollow vessel, which is 

 of equal size with the bore .of the elongated tube. 



In hydrostatics, it is assumed that liquid bodies 

 are practically incompressible. Such is not actually the 

 case, though pressure will only reduce their bulk so in- 

 considerably that the result of such action may practi- 

 cally be disregarded. 



The pressure of water of the height of one foot is 



