Although he is best known as one of the greatest mathematicians of all time, Carl Friedrich Gauss was also a pioneer in the study of magnetism and electricity. To facilitate an extensive survey of terrestrial magnetism, he invented an early type of magnetometer, which is a device capable of measuring the direction and strength of a magnetic field. Gauss also developed a consistent system of magnetic units and with Wilhelm Weber built one of the first electromagnetic telegraphs. Gauss's laws describing magnetic and electric fluxes served as part of the foundation upon which James Clerk Maxwell developed his famous equations and electromagnetic theory.