Pascal’s law — developed by French mathematician Blaise Pascal — states that when there is an increase in pressure at any point in a confined fluid,there is an equal increase at every other point in the container.
This is an important principle in hydraulics and explained the large amount of work a hydraulic system could do with very little liquid and minimal pressure.
Due to the fact that liquids are practically incompressible and that any force or pressure applied is equally transmitted in all directions, you could apply a moderate amount of pressure on a small area and that same pressure would be transmitted to a larger area without losing power and doing much more work.
The basic idea behind any hydraulic system is very simple: Force that is applied at one point is transmitted to another point using an incompressible fluid. The fluid is almost always an oil of some sort. The force is almost always multiplied in the process.
Hydraulic multiplication. The piston on the right has a surface area nine times greater than the piston on the left. When force is applied to the left piston, it will move nine units for every one unit that the right piston moves, and the force is multiplied by nine on the right-hand piston.