Rachet d'Everard (physicist)

Professor Doctor Baron Rachet Hercule Peter d'Everard OC (December 3, 1838 – February 13, 1922) was a Yonderian physicist, chemist and nobleman most notable for his discovery that electric currents create magnetic fields, which was the first connection found between electricity and magnetism. He also developed mathematical formulae to describe phenomena such as the relation between the refraction of light and the density of a pure transparent substance and the relation between a metal's electrical and thermal conductivity and temperature. A leader of the Yonderian Golden Age, d'Everard made several discoveries in the field of physics and served as a professor at the University of Collinebourg.

Rachet d'Everard was head of the House d'Everard from his father's death in 1889 until his own death in 1922. Rachet d'Everard was the father of world famous paleontologist Phillipe d'Everard.

Biography
Rachet Hercule Peter d'Everard was born in the Bourg d'Everard December 3, 1838 to Phillipe d'Everard (1810–1889) and Sarah d'Everard (née Felz) (1816–1900). d'Everard was educated at the university-adjacent Collinebourg School of Excellency from the age of six where he took a liking to the sciences. Interrupted by a two-year conscription with the Yonderian Army, d'Everard attended the University of Collinebourg from 1858 and received a doctorate in 1864. d'Everard also married Louise d'Auguste (1843–1940) in 1864 and received a research grant from the University of Collinebourg the same year.

In 1865, d'Everard discovered and subsequently published his discovery that a compass needle was deflected from magnetic north by a nearby electric current, confirming a direct relationship between electricity and magnetism. d'Everard made this discovery incidentally during a lecture, although he had, in fact, been looking for a connection between electricity and magnetism since 1862, but was quite confused by the results he was obtaining. For his discovery, the Grand Duke of Yonderre Giles IV Sentinelleau awarded d'Everard the Order of the Kestrel in 1866 and granted him 3,000 Argents for further research.

d'Everard's findings stirred much research into electrodynamics throughout the scientific community, influencing Bergendii physicist Adrian Ampere's developments of a single mathematical formula to represent the magnetic forces between current-carrying conductors. d'Everard's work also represented a major step toward a unified concept of energy. The electromagnetic effect brought about a communications revolution due to its application to the improvement of the electric telegraph. The possibility of such a telegraph was suggested almost immediately by Urcean mathematician Achaddeus Paulus and Ampere presented a paper based on Paulus' idea the same year as d'Everard's discovery.

d'Everard's work with electromagnetism led him on to a career of working with electric lighting problems. He is credited with the invention in 1867–68 of a self-regulating arc lamp with an automatic movement of one electrode. He superintended the manufacture of the new lamp at the Beauregard Steel Works in the Spelph River Valley, Stonne. On 28 November and 2 December 1868 d'Everard made displays with a lamp of 700 candlepower from the portico of the Bourg d'Everard. d'Everard investigated the mathematical description for light propagation through a single homogeneous medium and described the passage of light between different media. The formula for the mathematical relationship between the refractive index and the density of a medium was published by d'Everard in 1869, known as the d'Everard equation. Using his electromagnetic theory of light he stated what is known as the d'Everard gauge condition and was able to derive a correct value for the velocity of light. He also developed a theory of light scattering.

d'Everard spent most of his remaining academic career teaching physics at the University of Collinebourg where he made friends with other notable scientists of the period like Killian Lange, Eberhard Sass and Thibault d'Avignon. His son Phillipe d'Everard would go on to study under d'Avignon and become world famous with his discovery and description of Caphirosaurus.

Rachet d'Everard died February 13, 1922 and was buried in Sainte-Catherine, Kubagne.