Pascal's Principle
| HYDROSTATICSHydrostatics is that part of the general science of hydrodynamics that deals with the application of forces to fluids at rest. Among the chief principles of hydrostatics may be mentioned the following:(1) The intensity of pressure at any point of a fluid is the same in all directions; it is the same whether the surface that receives the pressure faces upwards, downwards, horizontally or obliquely.(2) When a fluid is confined, if the intensity of pressure in one part is increased, as by forcing in a piston or by any other means, an equal increase will be produced in the intensity of pressure at all other parts: in other words, pressure applied to any one part is transmitted without any change in its intensity to all other parts. This principle, which is known as Pascal's principle from being distinctly formulated by him, is the most important in hydrostatics, and finds a practical application in the Hydrostatic press, or Bramah's Press(3) Not only is pressure transmitted out to the surface or envelope of the liquid, but within the fluid itself the particlesare all pressed together. When a solid is immersed in the liquid it is pressed at every point of its surface in the direction perpendicular to the surface at that point.(3) In every horizontal layer throughout the liquid the pressure per unit area is the same; and this is the case independently of the shape of any vessel in which the liquid may be contained. The pressure per unit area in any horizontal layer depends only on the height of the free surface of the liquid above the layer considered, and the specific gravity of the liquid: and it is equal to the weight of a column of the liquid of unit sectional area whose height is the height of the free surface. Hence whatever be the shape or size of several vessels, if all have the same area of base, and if in all the water stands at the same height, the pressure on each of the bases is the same.(5) When a solid is immersed either partially or wholly