Discovery of magnetism

The discovery of magnetism began with a type of rock. The phenomenon of magnetism has been known at least as long as that of electricity. Plato’s Timaeus speaks not only of amber, but also of the ‘Heraclean stone’.

This was lodestone, a naturally magnetized piece of iron ore that can pick up small bits of iron and can also give them the same capability. Priest and people in Sumer, ancient Greece, China and pre-Colombian America were familiar with the natural magic of these magnets.

Lodestones were known in ancient China, and there are cryptic references to their use as compasses for magical purposes as early as 83 AD. There is evidence that a magnetized ladle was used for divination, testing the future by seeing which way the magnetic ladle lined up when spun.

There are records in Chinese literature of the 11th and early 12th centuries in which a magnetic needle, floating in water was used for navigational purposes.

Reinvention of compass in Europe a century later enabled the great voyages of discovery, including the European discovery of America by Christopher Columbus in 1492 and the earlier Chinese discovery of Africa by the eunuch admiral Cheng Ho in 1433.

Knowledge of magnetism lagged in the West, but the polarity of lodestone was noted in 1269 by Pierre de Maricourt. He discovered the existence of two magnetic poles and was the first to coin the term ‘polus’ to refer to the north and south ends of a magnet.

The foundations of a scientific understanding of magnetism were laid in Elizabethan London by William Gilbert.

Gilbert correctly guessed that this provides the explanation for the magnetic compass. It was Gilbert who was the first to perform a series of systematic experiments on magnetism, correctly realizing the Earth itself behave like a giant magnet.

In 1820 in Denmark, Hans-Christian Oersted eventually discovered the true connection between electricity and magnetism by accident. He demonstrated that current-carrying wire produced a circumferential field capable of deflecting a compass needle.
Discovery of magnetism