Much of modern science is based upon the theories and discoveries of William Gilbert, the brilliant English physician and physicist who was the first great experimental scientist. Gilbert was the first to use the word "electricity," to recognize mass as distinct from weight, to discover the effect of heat upon magnetic bodies, to differentiate clearly between static electricity and magnetism, and to explain phenomena of terrestrial magnetism in terms of the earth as a giant magnet. In 1600 he published De Magnete in Latin. As lively and entertaining as it was scientifically scrupulous, it summarized everything that had previously been known about electricity and magnetism, founded a new science and earned Gilbert the title of "the father of modern electricity." In it Gilbert explores magnetism and electricity, lodestones, phenomena of magnetism, direction of the earth's magnetic lines of force, variation in the compass, dip, the concept of the earth as a giant magnet, and much else. This Dover edition is a complete, unabridged reprinting of the definitive English translation of De Magnete prepared by Dr. P. Fleury Mottelay. Dr. Mottelay has added a number of footnotes that explain points that might be obscure to today's readers, who will find in this historically important text invaluable insights into the origins of modern science and physics. Translation by P. F. Mottelay. Biographical introduction. 90 illustrations.