This second edition of a textbook for advanced undergraduate and graduate students of geophysics reflects the most recent research on the natural magnetic fields in and surrounding the Earth arising from a variety of electric currents. Readers are introduced to the instrumentation for measuring geomagnetic fields, and to the applications of these techniques. Designed for use in a semester course, the volume includes student exercises at the end of each chapter. First Edition Hb (1997): 0-521-57193-6