Produced by Curtis Weyant, Keith Edkins and the Online Distributed Proofreading Team at http://www.pgdp.net (This file was produced from images generously made available by the Posner Memorial Collection (http://posner.library.cmu.edu/Posner/)) VVILLIAM GILBERT OF COLCHESTER, PHYSICIAN OF LONDON. ON THE MAGNET, MAGNETICK BODIES ALSO, AND ON the great magnet the earth; a new Physiology, _demonstrated by many arguments_ & experiments. [Illustration] LONDON * * * * * IMPRINTED AT THE CHISWICK PRESS ANNO MCM. * * * * * [Illustration] * * * * * {ij} [Illustration] PREFACE TO THE CANDID READER, STUDIOUS OF THE MAGNETICK PHILOSOPHY. Clearer proofs, in the discovery of secrets, and in the investigation of the hidden causes of things, being afforded by trustworthy experiments and by demonstrated arguments, than by the probable guesses and opinions of the ordinary professors of philosophy: so, therefore, that the noble substance of that great magnet, our common mother (the earth), hitherto quite unknown, and the conspicuous and exalted powers of this our globe, may be the better understood, we have proposed to begin with the common magnetick, stony, and iron material, and with magnetical bodies, and with the nearer parts of the earth which we can reach with our hands and perceive with our senses; then to proceed with demonstrable magnetick experiments; and so penetrate, for the first time, into the innermost parts of the earth. For after we had, in order finally to learn the true substance of the globe, seen and thoroughly examined many of those things which have been obtained from mountain heights or ocean depths, or from the profoundest caverns and from hidden mines: we applied much prolonged labour on investigating the magnetical forces; so wonderful indeed are they, compared with the forces of all other minerals, surpassing even the virtues of all other bodies about us. Nor have we found this our labour idle or unfruitful; since daily during our experimenting, new and unexpected properties came to light; and our Philosophy hath grown so much from the things diligently observed, that we have attempted to expound the interior parts of the terrene globe, and its native substance, upon magnetick principles; and to reveal to men the earth (our common mother), and to point it out as if with the finger, by real demonstrations and by experiments manifestly apparent to the senses. And as geometry ascends from sundry very small and very easy principles to the greatest and most difficult; by which the wit of man climbs above the firmament: so our magnetical doctrine and science first sets forth in convenient order the things which are less obscure; from these there come to light others that are more remarkable; and at length in due order there are opened the concealed and most secret things of the globe of the earth,