The origin of Maxwell's equations
Malcolm S. Longair · Cambridge University Press eBooks · 2003
How it all began Electricity and magnetism have an ancient history. Magnetic materials are mentioned as early as 800 bc by the Greek writers, the word ‘magnet’ being derived from the mineral magnetite, which was known to attract iron in its natural state and which was mined in the Greek province of Magnesia in Thessaly. Magnetic materials were of special importance because of their use in compasses, and this is reflected in the English word for the mineral, lodestone, meaning leading stone. Static electricity was also known to the Greeks through the electrostatic phenomena observed when amber is rubbed with fur – the Greek work for amber is elektron . The first systematic study of magnetic and electric phenomena was published in 1600 by William Gilbert (1544–1603) in his treatise De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure . The main subject of the treatise was the Earth's magnetic field, which he showed was similar to that of a bar magnet. He also described the force between two bodies charged by friction and named it the electric force between them. In addition to his famous experiments, in which he showed that lightning is an electrostatic discharge, Benjamin Franklin (1706–90) systematised the laws of electrostatics and defined the conventions for naming positive and negative electric charges. In the course of these studies, he also enunciated the law of conservation of electric charge .