TO THE REVERED MEMORY OF LORD KELVIN PREFACE The present work is the definitive edition of my “Chronological History of Magnetism, Electricity and the Telegraph,” which had tentative publication (1891–1892) serially in four leading technological Journals, viz. “Engineering” of London, “The Electrical World” of New York, “La Lumière Electrique” of Paris, and “L’Industrie Moderne” of Brussels. Since the time of that first publication, it has received a most thorough revision of the original text, for correction of faults of form, or of substance, suggested by learned critics conversant with the history of electricity and magnetism; and there have been added a very large number of new entries besides exhaustive notices of the work done by Peregrinus, Gilbert, Oersted, Faraday and other great pathfinders, also biographical and bibliographical notices of all the prominent ancient writers mentioned in the original compilation. This bibliography commences B.C. 2637--conclusively shown to be the earliest date at which history notes anything resembling the application of the magnetic influence--and it ends with Michael Faraday, esteemed by Tyndall to be “the greatest experimental philosopher the world has ever seen,” and who is held “to have done more for the development of electrical science than any other investigator.” Thus is the chronological series shown to cover 4458 years, being purposely made to terminate at A.D. 1820–1821 (Oersted, Ampère, Arago, Faraday, etc.), the culminating period when, through the splendid discovery of electro-magnetism, the two immense groups of phenomena were first linked together. Besides the matter distinctly involved in the title of the new work, it has been deemed advisable to note in this History all the most important forms of the optical telegraph, or semeiograph. Many of the ancient and historical methods for communicating intelligence swiftly at great distances are noticed in their chronological order: doubtless, this will prove to the generality of readers no less interesting than the vast multitude of curious facts pertaining to the direct line of researches. An exhaustive cross-entry Index of Selected Names and Subjects, embracing fuller titles and much additional data that could not well be entered into the body of the work, will, for the first time, make this mass of historical data readily accessible.