Charles-Augustin de Coulomb (1736-1806), a military civil engineer, retired from the French army because of ill health after years in the West Indies. Forced from Paris by the disturbances of the revolution, he began working at his family estate and discovered that the torsion characteristics of long fibers made them ideal for the sensitive measurement of magnetic and electric forces. He was familiar with Newton's inverse-square law and in the period 1785-1791 he succeeded in showing that electrostatic forces obey the same rule.