Introduction

Practical needs stimulated the growth of ancient counting, geometry and astronomy. Not so with electricity and magnetism. Various curious properties uncovered by the ancient Greeks seemed to offer no solutions to the practical problems of the day, and instead became fodder for myth, legend and misconception.

The ancients had some familiarity with both magnetism and static electricity, although in those early days no distinction was made between the two. Awareness of magnetism came first. The Greek historian Pliny the Elder (23–79 ce) wrote that when the Greek shepherd Magnes chanced upon a lodestone, the iron tip of his staff as well as his iron hobnail boots were attracted to it. The shepherd's name has become immortalized in magnet, as well as the region's name Magnesia and the element magnesium. Pliny put the date at around 900 bce, but there are Chinese writings going back to 4000 bce that also mention naturally magnetic iron.

It's thought that around 300 bce the Chinese general Huang-ti fashioned a compass, possibly by putting a small lodestone in a bowl floating in a pan of water. Lodestone compasses were used by Chinese military commanders during the ensuing century, and after the Dark Ages the effect was rediscovered by the Italian scholar Petrus Peregrinus (1220–?). He wrote the first important study of magnetism, Epistola de Magnete, which includes a description of magnetic attraction and repulsion.