De Magnete
William Gilbert
 De Magnete consists of six books. # Historical survey of magnetism and theory of Earth's magnetism. # Distinction between electricity and magnetism. Argument against perpetual motion. # The terrella experiments. # Declination (the variation of magnetic north with location). # Magnetic dip and Design of the magnetic inclinometer. # Magnetic theory of stellar and terrestrial motion. Precession of the equinox.