Overview

The earliest experimental study of magnetism can be found in a letter written by Petrus Peregrinus in 1269. Peregrinus was the first individual to describe the existence of two magnetic poles in each magnet, to describe the attraction between unlike poles, and to explain the creation of new poles when a magnet is broken in two. A designer of instruments, Peregrinus also described improvements in the magnetic compass, which made it far more useful for navigation on the high seas. Roger Bacon, a Franciscan friar teaching at the universities of Oxford and Paris, popularized the experiments of Peregrinus, including studies now lost. The letter about magnets was copied numerous times and widely circulated. Later it would stimulate the researches of William Gilbert, an English physician whose treatise on magnets would initiate the modern study...