William Gilbert

Source

• Born: 24 May 1544
• Birthplace: Colchester, Essex, England
• Died: 30 November 1603 (plague)
• Best Known As: The guy who figured out magnetism and electricity

In 1600 William Gilbert published De Magnete ("On Magnets"), one of the first scientific books in the English language and the first to suggest that the earth was a big magnet. A prominent physician, Gilbert studied magnetism and lodestones for nearly two decades, seeking to explain the behavior of compasses. His book, which also suggested that a vacuum must exist between planets, was a huge success and is considered the first work to discuss the connection between magnetism and electricity. Gilbert was also the royal physician for Queen Elizabeth I and her successor, King James I.

The gilbert, a unit of magnetomotive force, is named after him.

William Gilbert

Library of Congress

[b. Colchester, Essex, England, May 24, 1544, d. London, November 30, 1603]

Gilbert's book De magnete (in English called On the Magnet, Magnetick Bodies Also, and on the Great Magnet the Earth), published in 1600, is among the seminal works of the Scientific Revolution. Gilbert describes his experiments with lodestones and compasses, gives methods of making iron display magnetic effects, introduces the concept of magnetic poles, and recognizes the magnetic field of Earth.

The English physician and physicist William Gilbert (1544-1603), an investigator of electrical and magnetic phenomena, is principally noted for his "Demagnete," one of the first scientific works based on observation and experiment.

William Gilbert was born in Colchester, Suffolk, on May 24, 1544. He studied medicine at St. John's College, Cambridge, graduating in 1573. Four years later he began practicing in London. He was prominent in the College of Physicians and became its president in 1599. The following year he was appointed physician to Queen Elizabeth I, and a few months before his death on Dec. 10, 1603, physician to James I.

In 1600 Gilbert published De magnete (On the Magnet, on Magnetic Bodies, and Concerning That Great Magnet, the Earth: A New Physiology), in Latin. The first major scientific work produced in England, it reflected a new attitude toward scientific investigation. Unlike most medieval thinkers, Gilbert was willing to rely on sense experience and his own observations and experiments rather than the authoritative opinion or deductive philosophy of others. In the treatise he not only collected and reviewed critically older knowledge on the behavior of the magnet and electrified bodies but described his own researches, which he had been conducting for 17 years.

In electrostatics Gilbert coined the word "electricity," greatly extended the number of known materials exhibiting electric attraction, and suggested that static electric attraction was due to a subtle electric effluvium emitted by electrified bodies. The greater bulk of the work, however, is devoted to magnetism. Although the compass had been known in Europe for at least 4 centuries, Gilbert's was the first important study on the detailed behavior of compass needles, their variation from true north, and the tendency of the north pole of the needle to dip. From experiments involving a spherical lodestone, the most powerful magnet then available, Gilbert concluded that the earth was a huge magnet, with a north and south magnetic pole coinciding with the rotational poles. The variation in compass readings from true north, he believed, was due to land masses.

Gilbert also speculated on the nature of magnetism, suggesting that magnetic bodies had a kind of soul which spontaneously attracted other bodies. He pointed out that gravity might be a sort of magnetism, or was at least analogous to it, and that the motions of the planets might well be explained by considering their mutual influence.

Gilbert's studies were so complete and comprehensive that as late as 1822 it was asserted that De magnete contained almost everything known about magnetism. Today the unit of magnetomotive force is called the gilbert.

Further Reading

Gilbert's De magnete (On the Magnet) is available in several translations, such as those of S. P. Thompson and P. Fleury Mottelay. The only complete biography of Gilbert is Silvanus P. Thompson, Gilbert of Colchester: An Elizabethan Magnetizer (1891), which is now difficult to obtain. Romano Harré, Early Seventeenth Century Scientists (1965), has a full chapter on Gilbert. A brief biography is given in George Sarton, Six Wings: Men of Science in the Renaissance (1957). Most standard histories of science discuss Gilbert's contributions. See particularly Abraham Wolf, A History of Science, Technology, and Philosophy in the 16th and 17th Centuries (2 vols., 1939; 2d ed. 1959).

Gilbert, William, 1544–1603, English scientist and physician. He studied medicine at Cambridge (M.D., 1569), where he was elected a Fellow of St. John's College, and set up practice in London, becoming president of the College of Physicians (1599) and court physician to Queen Elizabeth I (1600) and later also to James I. He is best known, however, for his studies of electricity and magnetism. He coined the word electricity (from the Greek for “amber”), was the first to distinguish clearly between electric and magnetic phenomena, and published (1600) De Magnete, the most important work on magnetism until the early 19th cent. In it he described his methods for strengthening natural magnets (lodestones) and for using them to magnetize steel rods by stroking; he also outlined his investigations of the earth's magnetic field, from which he concluded that the earth as a whole behaves like a giant magnet with its poles near the geographic poles. He found that an iron bar that is left in alignment with the earth's magnetic field will slowly become magnetized, and that sufficient heating will cause a magnet to lose its magnetism.

Bibliography

See translations of his De Magnete by P. F. Mottelay (1893, repr. 1958) and S. P. Thompson (1901, repr. 1958).

Gilbert, William (1544–1603), English scientist and physician. Gilbert is best known for his revolutionary theories on magnetism, published in his book De Magnete (or De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure; On the loadstone and magnetic bodies, and on the great magnet the Earth) in 1600. Remarkably little is known of Gilbert's life. Born in Colchester to a prosperous magistrate, he received a B.A. from Cambridge University in 1561, an M.A. in 1564, and an M.D. in 1569. By the mid-1570s, he was practicing medicine in London, where he became a member of the Royal College of Physicians (and was elected president of the group in 1600). There, he also came into contact with navigators, compass makers, and practical mathematicians, and pursued his research on magnetism. In his successful medical practice, he was consulted by members of the aristocracy, was appointed as one of Elizabeth I's personal physicians (1600–1603), and, after her death in 1603, served as James I's physician until a plague epidemic that November took his own life.

Navigational accuracy assumed greater importance with the overseas explorations by the Spanish and Portuguese in the fifteenth century, and during the sixteenth century Dutch and English navigators compiled observations that were of significant use to Gilbert. It was not lost on Gilbert or his contemporaries that discoveries about magnetism would be politically and commercially useful. Despite the widespread use of nautical compasses on Spanish, English, Dutch, and French ships, none of his contemporaries understood why compass needles behaved as they did: attraction, repulsion, variation, dip, bipolarity, and the discovery of latitude were recognized empirically, but poorly understood. Through his experiments on magnets and magnetic bodies (especially the lodestone, that is, naturally magnetized iron ore), Gilbert methodically investigated a wide range of magnetic behaviors.

In fact, Gilbert's book went far beyond being a useful navigational treatise, and represented the first comprehensive analysis of magnetism, featuring a revolutionary new theory about the Earth's magnetic force. In formulating his views, Gilbert insisted on using his own empirical data rather than relying on past scientific authorities. His book is full of carefully contrived laboratory experiments that he urged his readers to replicate. He assailed credulous acceptance of myths (such as the power of a magnet to detect adultery), rejected Aristotelian explanations, and invented his own language to describe magnetic phenomena, including the terms electricity, electric force, electric attraction, and magnetic pole. To explain the phenomena he investigated, he concluded that the Earth was alive with magnetic potency or force, and he likened this to sexual attraction. Hence, for him, magnetism was an immaterial, innate force operating in the universe, with occult and vital properties.

The stunning claim of Gilbert's book was that the Earth behaves in the heavens as a spherical magnet does on earth. He based this assertion on his experiments with spherical magnets and on his deduction that the Earth itself was a giant spherical magnet. Reasoning by analogy, he stated boldly that the Earth rotated daily on its own axis by its magnetic power, just as a perfectly spherical lodestone aligned with the Earth's poles would spin on its axis. Declaring himself an adherent of astronomer Nicolaus Copernicus (1473–1543), whose theory about the Earth's rotation around the heavens had been published in 1543, Gilbert added new magnetic arguments to the arsenal of the Copernican polemic.

Influence on Later Science

Subsequent natural philosophers including Francis Bacon (1561–1626) and Galileo Galilei (1564–1642) hailed Gilbert's handling of empirical and experimental evidence, and others applauded his rejection of Aristotle's erroneous ideas about physics and astronomy. Johannes Kepler (1571–1630) and Sir Isaac Newton (1642–1727) pondered Gilbert's magnetic forces before devising their own physical explanations of astronomical motions. And, although many parts of Gilbert's new magnetic theories were soon rejected, including his analogy of the Earth and the spherical lodestone, he is still acknowledged for some of his discoveries about electricity and magnetism (such as the distinction between magnetic and static electricity), and for correctly recognizing that the fixed stars are not all the same distance from the earth.

Bibliography

Gilbert, William. On the Loadstone and Magnetic Bodies, and on the Great Magnet the Earth. Translated by P. Fleury Mottelay. New York, 1958.

Pumfrey, Stephen. Latitude and the Magnetic Earth. Cambridge, U.K., 2002.

Roller, Duane H. D. The De Magnete of William Gilbert. Amsterdam, 1959.

—MARTHA BALDWIN

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