On May 24, 1544, English physician, physicist and natural philosopher William Gilbert was born. He passionately rejected both the prevailing Aristotelian philosophy and the Scholastic method of university teaching. He is remembered today largely for his book De Magnete (1600), and is credited as one of the originators of the term “electricity“. He is regarded by some as the father of electrical engineering or electricity and magnetism.
William Gilbert attended St John’s College, Cambridge and left to practice medicine in London after graduating. In 1573, Gilbert was elected a Fellow of the Royal College of Physicians and later he also became president of the College. For a few years, it is believed, that William Gilbert was Elizabeth I‘s own physician.
To his most important works belongs De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure (On the Magnet and Magnetic Bodies, and on the Great Magnet the Earth). It is the first summary treatment of magnetism since Petrus Peregrinus de Maricourt in the 13th century. In this work, published in 1600, Gilbert described many of his experiments with his model Earth called the “Terrella” (Latin “small earth“). From these experiments, he concluded that the Earth was itself magnetic and that this was the reason compasses point north. While some of his contemporaries thought that the tip of the compass needle was attracted to the polar star, he showed convincingly that the earth as a whole must be regarded as a single magnet with two poles. He also concluded this from the inclination of the magnetic needles discovered by Georg Hartmann and published by Robert Norman (The New Attractive 1581). However, the decisive factor was his own experiments with a spherical magnet. According to his imagination, magnetism was the “soul” of the earth and was implanted in it by God. He assigned each magnet a sphere of influence, a precursor of the field concept. He suggested that seafarers should record deviations from the direction of the magnetic needle to the North Pole and gave instructions for this.
Like Peregrinus, Gilbert believed that rotation was one of the magnetic movements and that a balanced spherical magnet would rotate. In the sixth book of his De Magnete, in which he transferred his magnetic philosophy to the cosmos, he argued that the daily rotation of the earth was due to magnetism. He rejected the idea of a fixed star sphere with a fixed distance. Tides and the precession of the equinoxes he also tried to attribute to magnetism, but the arguments were weak and the sixth book of his major work was therefore criticized by Francis Bacon and others.
It is further assumed that Gilbert was the first to argue that the centre of the Earth was iron, and he considered an important and related property of magnets was that they can be cut, each forming a new magnet with north and south poles. In the work, Gilbert further argued that the “fixed” stars are at remote variable distances rather than fixed to an imaginary sphere.
On this day, it is assumed that the term electricity was first used by Sir Thomas Browne in 1646, probably derived from Gilbert’s 1600 New Latin electricus, meaning “like amber”. He recognized that friction with these objects removed a so-called “effluvium”, which would cause the attraction effect in returning to the object, though he did not realize that this substance was universal to all materials. In his book, he also studied static electricity using amber; amber is called elektron in Greek, so Gilbert decided to call its effect the electric force. He invented the first electrical measuring instrument, the electroscope, in the form of a pivoted needle he called the versorium. In his book, Gilbert also studied static electricity using amber. Since amber is called elektron in Greek, Gilbert decided to call its effect the electric force. Gilbert is credited with inventing the first electrical measuring instrument, the electroscope, in the form of a pivoted needle he called the versorium. William Gilbert also pointed out that electricity and magnetism were not the same thing. Hans Christian Ørsted and James Clerk Maxwell later correctly showed that both effects were aspects of one single force: electromagnetism.
A collection of Gilbert’s unfinished writings was collected in 1651 by his half-brother William Gilbert of Melford under the title De Mundo Nostro Sublunari Philosophia Nova (New Philosophy about our sublunar world) and were known for example to Francis Bacon and Thomas Harriot. They were published in Amsterdam in 1651. It was unfinished and the first part (Physiologiae nova contra Aristotelem, probably 1590s) continued the cosmological ideas from the last book of De magnete and presupposed its terms. The second part Nova meterorologia contra Aristotelem probably originated as an independent work and deals with comets, the Milky Way, rainbows, clouds, wind, tides and the sea, origin of rivers and others. However, the legacy of his writings was far less influential than his main work, which proved to be groundbreaking for the scientific research of future generations.
References and Further Reading:
-  William Gilbert at NASA
-  The Natural Philosophy of William Gilbert and His Predecessors
-  William Gilbert at BBC
-  The Virgin Queen – Elizabeth I., SciHi Blog
-  Sir Francis Bacon and the Scientific Method, SciHi Blog