The first reports on the influence of an electrical charge on a liquid date back to the turn of the 17th century. At the time, scientists followed the Aristotelian approach and musing about phenomena without any real urge to verify. William Gilbert was among a new generation of natural philosophers that rejected this Aristotelian approach and instead performed experiments to test prevailing views. The culmination of his experiments was published in the treatise, “De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure”, or “On the Magnet and Magnetic Bodies, and on the Great Magnet the Earth.” At the time, it was believed that a compass pointed north due to either Polaris, the North Star, or a magnetic island near the north pole, that rubbing a magnet with a diamond would reverse its polarity, and that a compass was influenced by nearby garlic. In De Magnete, Gilbert proposed that the Earth is a giant magnet driven by a core of iron, and that this magnetism is what causes a compass to point north. He also dismissed the concept that the stars are fixed points on a celestial sphere that rotates around a fixed Earth, and concluded that the Earth instead rotates, leading to an apparent daily motion.
Gilbert also provided the first descriptions of static electricity generated by friction, which today is called the triboelectric effect. He noted that after rubbing an object with amber, there was an “effluvium” transferred from the object that resulted in an attractive force he termed an electric force. The word electric was taken from the Greek word for amber, elektron. He also defined the transfer of “effluvium” as electrikus, meaning “like amber”, which was later altered to “electricity” by Sir Thomas Browne in 1646.
With regard to electrospinning, Gilbert’s key finding was that when a piece of charged amber was brought near a spherical drop of water on a dry surface, the amber “…pulls the nearest parts out of their position and draws it up into a cone.” This observation is the first record of what is now referred to as a Taylor cone.
One notable tool developed by Gilbert for these studies possible was a versorium (Latin for “turn around”), which was the world’s first electrometer. The device is simply a non-magnetic needle that was free to pivot on a pedestal. The device was essentially the same as a magnetic compass, but rather than detecting magnetic fields, it could be used to detect electrostatically charged objects. Gilbert used the versorium, which was the world’s first electrometer, to differentiate between insulating (“electrik”) and conducting (“non-elektrik”) materials. These studies were the first to demonstrate that electricity and magnetism were different. It would take another 250 years before the two phenomena were ultimately reconnected as electromagnetism by James Clerk Maxwell and Hans Christian Orsted.
Sadly, his day job as the physician to Elizabeth I required that he live in the bustling center of London at the time of the Bubonic Plague, which likely lead to his death in 1602 or 1603.
Poetic introduction to De Magnete:
“At an early period, while philosophy lay as yet rude and uncultivated in the mists of error and ignorance, few were the powers and properties of things that were known and clearly perceived: there was a bristling forest of plants and herbs, things metallic were hidden, and the knowledge of stones was unheeded.” -- Book I, Chapter I
“It is probable therefore that amber does exhale something peculiar to itself, which allures bodies themselves, not the intermediate air. Indeed it plainly does attract the body itself in the case of a spherical drop of water standing on a dry surface; for a piece of amber applied to it at a suitable distance pulls the nearest parts out of their position and draws it up into a cone; otherwise, if it were drawn by means of the air rushing along, the whole drop would have moved… But it may be asked why does amber allure water, when water placed on its surface removes its action? Evidently because it is one thing to suppress it at its very start, and quite another to extinguish it when it has been emitted… Moisture also from spent air, and any breath blown from the mouth, as well as water put on the amber, immediately extinguishes its force.” -- Book Second, Chapter II
In De Magnete, he not only describes his observation, but encourages the reader to test the effect themselves:
“In order that you may be able clearly to test how such attraction occurs, and what those materials are which thus entice other bodies… make yourself a versorium of any metal you like, three or four digits in length, resting rather lightly on its point of support after the manner of a magnetic needle, to one end of which bring up a piece of amber or a smooth and polished gem which has been gently rubbed; for the versorium turns forthwith.” -- Book Second, Chap. II
“One may very easily fall into mistakes and errors when one is searching into the hidden causes of things, in the absence of real experiments.” -- Book Fourth, Chapter XI
“We may see how far from unproductive magnetic science is, how agreeable, how helpful, how divine!” -- Book Fifth, Chap. VIII
Long, but fantastically scathing takedown of the idea that the Earth is stationary and the stars rotate around the Earth:
“That Primum Mobile bears no visible body, is nohow recognizable, is a fiction believed in by those people, accepted by the weak-minded folk, who wonder more at our terrestrial mass than at bodies so vast, so inconceivable, and so far separated from us. But there can be no movement of infinity and of an infinite body, and therefore no daily revolution of that vastest Primum Mobile… The Moon being neighbour to the Earth revolves in 27 days; Mercury and Venus have their own moderately slow motions; Mars finishes a period in two years, Jupiter in twelve years, Saturn in thirty. And those also who ascribe a motion to the fixed stars make out that it is completed in 36,000 years, according to Ptolemy, in 25,816 years, according to Copernicus’ observations; so that the motion and the completion of the journey always become slower in the case of the greater circles. And would there then be a daily motion of that Primum Mobile which is so great and beyond them all immense and profound? ’Tis indeed a superstition and in the view of philosophy a fable now only to be believed by idiots, deserving more than ridicule from the learned: and yet in former ages, that motion, under the pressure of an importunate mob of philosophizers, was actually accepted as a basis of computations and of motions, by mathematicians...” -- Book Sixth, Chap III
William Gilbert portrait, Wikipedia
Illustrations from Gilbert’s De Magnete