As French physicists Guillaume Amontons and Charles-Augustin de Coulomb
established in the 17th and 18th centuries, the sideways force needed to overcome the friction between surfaces is proportional to the forces, such as weight, pressing the surfaces together.
In 1777, however, the French physicist Charles-Augustin de Coulomb
(1736-1806) showed that it took a certain amount of force to twist (that is, to apply torsion to) a fiber or a wire, and that the amount of torsion was proportional to the amount of force.
In 1784, French physicist Charles-Augustin de Coulomb
developed the torsion-balance electrometer, a sensitive device that measures electric forces.