Overview

Beginning in the late sixteenth century with the work of William Gilbert on magnets, an increasing number of individuals began to sort out the difference between electric and magnetic phenomena and to develop an understanding of Earth's magnetism. Gilbert, an eminent English physician, was among the first to carefully distinguish between magnetic phenomena and those associated with static electricity. He studied the properties of a magnetized solid iron sphere and showed that they matched those of Earth as a whole. Other researchers mapped Earth's magnetic field more precisely and showed that it varied in time.

Background

The basic phenomena of magnetism and static electricity were known to the ancient Greeks. The philosopher Thales (624-546 B.C.) was familiar with lodestone, a naturally occurring magnetic rock, and felt it necessary to attribute to it a soul because it was able...