Friction of Class 8
The classic rules of sliding friction were discovered by Leonardo da Vinci (1452–1519) but remained unpublished in his notebooks. They were rediscovered by Guillaume Amontons (1699). Amontons presented the nature of friction in terms of surface irregularities and the force required to raise the weight pressing the surfaces together. This view was further elaborated by Belidor (representation of rough surfaces with spherical asperities, 1737) and Leonhard Euler (1750) who derived the angle of repose of a weight on an inclined plane and first distinguished between static and kinetic friction.
A different explanation was provided by Desaguliers (1725), who demonstrated the strong cohesion forces between lead spheres of which a small cap is cut off and which were then brought into contact with each other.