Tomlinson Movie
Macroscopic Friction
The law of Leonardo (da Vinci)
The law of Euler and Amontons
The law of Coulomb
Historical abstract
Adhesion models
Friction Force Microscopy
Principle of measuring
Measuring Topology
Measuring Friction
Both Channels
Self assessment
Tomlinson's mechanism
Phenomenology I
Phenomenology II
Mechanical adiabaticity
Distinguish positions
Playing Tomlinson
Friction - a pinning problem
2D Friction
Critical Curves
Historical Background
Research Projects
Simulator Applet
The first Picture
The Panels
Post processing

Guillaume Amontons (1663-1705)


The spring D measures the friction force during the sliding process between materials A and B. Spring C adjusts the normal force.
Two centuries after Leonardo's discoveries, the French physicist Guillaume Amontons considered the problem of friction again. In his experiments he used springs to measure lateral forces and therefore he must have been able to measure both static and kinetic friction. However, we must conclude, that also Amontons wasn't aware of the difference of the two friction phenomena. Amonton postulated the following friction laws:
  • The resistance caused by rubbing only increases or diminishes in proportion to greater or lesser pressure (load) and not according to the greater or lesser extent of the surfaces.
  • The resistance caused by rubbing is more or less the same for iron, lead, copper and wood in any combination if the surfaces are coated with pork fat
  • The resistance is more or less equal to one-third of the pressure (load).
Amontons found a material-independent friction coefficient of 0.33 and therefore also he believed in the existence of a universal friction coefficient.
  Leonardo da Vinci (1452-1519)                  Leonhard Euler (1707-1783)

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