Fundamentals of Geophysics: Geomagnetism and paleomagnetism

摘要: HISTORICAL INTRODUCTION The discovery of magnetism Mankind's interest in began as a fascination with the curious attractive properties mineral lodestone, naturally occurring form magnetite. Called loadstone early usage, name derives from old English word load, meaning “way” or “course”; was literally stone which showed traveller way. earliest observations were made before accurate records discoveries kept, so that it is impossible to be sure historical precedents. Nevertheless, Greek philosophers wrote about lodestone around 800 BC and its known Chinese by 300 BC. To ancient Greeks science equated knowledge, considered an element philosophy. As result, forces ascribed metaphysical powers. Some animistic even believed possess soul. Contemporary mechanistic schools thought equally superstitious gave rise false conceptions persisted for centuries. Foremost among these view electrical magnetic related invisible fluids. This well into nineteenth century. power magnet seemed flow one pole other along lines induction could visible sprinkling iron filings on paper held over magnet. term “flux” (synonymous flow) still found “magnetic flux density,” regularly used alternative induction” fundamental field vector B .