Gilbert, Walter (1544-1603)

English scientist who studied magnetism and static electricity, deducing that the Earth's magnetic field behaves as if a bar magnet joined the North and South poles. His book on magnets, published 1600, is the first printed scientific book based wholly on experimentation and observation. Gilbert was the first English scientist to accept Nicolas Copernicus' idea that the Earth rotates on its axis and revolves around the Sun. He also believed that the stars are at different distances from the Earth and might be orbited by habitable planets, but erroneously thought that the planets were held in their orbits by magnetic forces. Gilbert was born in Colchester, Essex, and educated at Cambridge. In about 1573, he settled in London, where he established a medical practice. He was appointed physician to Queen Elizabeth I 1600 and later briefly to James I. Gilbert discovered many important facts about magnetism, such as the laws of attraction and repulsion and magnetic dip. He also investigated static electricity and differentiated between magnetic attraction and electric attraction (as he called the ability of an electrostatically charged body to attract light objects). This is described in his book De magnete, magneticisque corporibus, et de magno magnete tellure/Concerning Magnetism, Magnetic Bodies, and the Great Magnet Earth 1600.