Pascal's Law (from Blaise Pascal 1623 to 1662), comprises a set of principles
formulated in 1648.
The principles state that pressure applied to a confined fluid
at any point is transmitted undiminished throughout the fluid in all directions
and acts upon every part of the confining vessel at right angles to its
interior surfaces and equally upon equal areas.
This is the basic principle behind any hydraulic system, that pressure applied
anywhere to a body of fluid causes a force to be transmitted equally in
all directions, with the force acting at right angles to any surface in
contact with the fluid.