Charles Augustin Coulomb (14.06.1736—23.08.1806) was a French physicist and military engineer and a member of the Paris Academy of Sciences (1803). He was born in Angoulême. He graduated (1761) from the school of military engineers and was in military service all his life.
His work was in the field of electricity, magnetism and applied mechanics. In 1781 he formulated the laws of friction, of rolling and of sliding. Studying the torsion of silk and metal threads, he established the laws of elastic torsion; in particular he determined that the force twisting a thread depends on the material of which the thread is made, is proportional to the angle of twist and to the fourth power of the diameter of the thread, and is inversely proportional to its length. This was important, because it gave a new and very sensitive method of measuring force. Starting from it, he built in 1784 an instrument for measuring force, the torsion balance. With its help he established experimentally in 1785 the fundamental law of electrostatics (Coulomb's law), which he extended in 1788 to the interaction of point magnetic poles. He put forward a hypothesis of magnetism according to which magnetic fluids are not free, or cannot flow as their electrical analogues do, and are bound to individual molecules. He supposed that in the course of magnetisation each molecule becomes polarised. He constructed a magnetometer (1785). He laid the foundations of electrostatics and magnetostatics. He tried to measure experimentally (1796) the friction in a liquid from the damping of the oscillations of a pendulum moving in it, and to determine how friction depends on velocity.