Sketching the History of Classical Electromagnetism
(Optics, Magnetism, Electricity, Electromagnetism) 
© 19962008 HyperJeff Network
History  Philo  Physics  Blog [ Sources, Links, Notes ] 
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Many things are known about optics: the rectilinearity of light rays; the law of reflection; transparency of materials; that rays passing obliquely from less dense to more dense medium is refracted toward the perpendicular of the interface; general laws for the relationship between the apparent location of an object in reflections and refractions; the existence of metal mirrors (glass mirrors being a 19th century invention).  

ca 300 BC 
Euclid of Alexandria (ca 325 BC  ca 265 BC)
writes, among many other works, Optics, dealing with vision theory and perspective.
Convex lenses in existence at Carthage. 

1st cent BC 
Chinese fortune tellers begin using loadstone to construct their divining boards, eventually leading to the first compasses. (Mentioned in Wang Ch'ung's Discourses weighed in the balance of 83 B.C.)  
1st cent 
Southpointing divining boards become common in China.  
2nd cent 
Hero of Alexandria writes on the topics of mirrors and light.
Claudius Ptolemy (ca 85  ca 165) writes Optics, an experimental and mathematical treatment, extending earlier work on reflection by Euclid and Hero, including both concave and convex spherical and cylindrical mirrors, and doing original research on refraction. 

ca 271 
True compasses come into use by this date in China.  
6th cent 
(China) Discovery that loadstones could be used to magnetize small iron needles.  
11th cent 
Abu Ali alHasan ibn alHaitam (Alhazen) (9651039)
writes Kitab almanazir (translated into Latin as Opticae thesaurus Alhazeni in 1270)
on optics, dealing with reflection, refraction, lenses, parabolic and spherical mirrors,
aberration and atmospheric refraction. He adapts the mathematical extramission theory (which he rejects)
to the intramission framework.
(China) Iron magnetized by heating it to red hot temperatures and cooling while in southnorth orientation. 
alHaitam (Alhazen) 
1086  Shen Kua's Dream Pool Essays make the first reference to compasses used in navigation.  
1150s  Earliest explicit reference to magnets per se, in Roman d'Enéas. (see reference)  
1190s  Alexander Neckam's De naturis rerum contains the first western reference to compasses used for navigation, and it had by this time been in common use.  
13th cent 
Robert Grosseteste (11681253)
writes De Iride and De Luce on optics and light, experimenting with both
lenses and mirrors.
Roger Bacon (12141294) writes many works on the nature of light and optics (and some on magnetism). Greatly furthering the work of Grosseteste and Alhazen, and having access to and mastery of the major literature on optics, Bacon develops a unified framework for the understanding of light and geometric optics. Pierre de Maricourt, a.k.a. Petri Pergrinus (fl. 1269) writes Letter on the magnet of Peter the Pilgrim of Maricourt to Sygerus of Foucaucourt, Soldier, the first western analysis of polar magnets and compasses. He demonstrates in France the existence and fundamental role of two poles of a magnet by tracing the directions of a needle laid on to a natural magnet. Witelo (d after 1281) writes Perspectiva around 1270, treating geometric optics, including reflection and refraction. He also reproduces the data given by Ptolemy on optics, though was unable to generalize or extend the study. John Pecham's (d. 1292) work on optics and light. Theodoric of Freiberg (ca 1250  ca 1310), working with prisms and transparent crystalline spheres, formulates a sophisticated theory of refraction in raindrops which is close to the modern understanding, though it did not become very well known. (Descartes presents a nearly identical theory roughly 450 years later.) Eyeglasses, convex lenses for the farsighted, first invented in or near Florence (as early as the 1270s or as late as the late 1280s  concave lenses for the nearsighted appearing in the late 15th century). 

16th cent 
Girolamo Cardano (15011576) elaborates the difference between amber and loadstone.  
1558  Giambattista Della Porta (15351615) publishes his major work, Magia naturalis, analyzing, among many other things, magnetism.  
1600  William Gilbert (15441603), after 18 years of experiments with magnetic and electrical materials, finishes his book De Magnete. The work included: the first major classification of electric and nonelectric materials; gives the name "electric" to the substance behind electrical phenomena; a comarative study of electric and magnetic field effects; the relation of moisture and electrification; showing that electrification effects metals, liquids and smoke; noting that electrics were the attractive agents (as opposed to the air between objects); that heating dispelled the attractive power of electrics; and showing the earth to be a magnet. 
William Gilbert 
1606  Della Porta first describes the heating effects of light rays.  
1618  April 2nd, Francesco Maria Grimaldi discovers diffraction patterns of light and becomes convinced that light is a wavelike phenomenon. The theory is given little attention.  
1621  Willebrord van Roijen Snell (15801626) experimentally determines the law of angles of incidence and reflection for light and for refraction between two media.  
1629  Nicolo Cabeo (15861650) publishes his observations on electrical repulsion, noting that attracting substances may later repel one another after making contact.  
1630  Vincenzo Cascariolo discovers a substance that shines in the dark after exposure to sunslight, the socalled Bologna phosphorus.  
1637  René Descartes publishes his Dioptics and On Meteors as appendices to his Discourse on a Method, detailing a theory of refraction and going over a theory of rainbows which, while containing nothing essentially new, encouraged experimental exploration of the subject.  
1644  Descartes' Principia philosophiae, describing magnetism as the result of the mechanical motion of channel particles and their displacements, and proposing the absence of both void and action at a distance.  
1646  Thomas Browne (16051682) coins the term "electricity" in his Pseudodoia Epidemica.  
1657  Pierre de Fermat (16011665) formulates the principle of least time for understanding the way in which light rays move. 
Pierre de Fermat 
1660  Otto von Guericke (16021686) builds the first electrical machine, a rotating frictional generator.  
1661  Fermat is able to apply his principle of least time to understand the refractive indices of different materials.  
1664  Robert Hooke (see also: Robert Hooke) (16351703) puts forth a wave theory of light in his Micrographia, considering light to be a very high speed rectilinear propagation of longitudinal vibrations of a medium in which individual wavelets spherically spread. He also introduces wavefront analysis, the nation of a material's optical density and a theory of color.  
1665  Francesco Maria Grimaldi's Prysicomathesis de lumine coloribus et iride describes experiments with diffraction of light and states his wave theory of light.  
1669  Erasmus Bartholin publishes A Study of Iceland Spar, about his discovery of double refraction.  
1671  Isaac Newton presents his observations on color and suggests color to be a property of light rays.  
1672  Newton presents a corrected account of Huygen's discover of polarization phenomena.  
1675  Robert Boyle (162791) writes Experiments and Notes about the Mechanical Origine or Production of Electricity. Electrical attraction, it was written, was "a Material Effluvium issuing from and returning to, the Electrical Body."  
1676  Ole Christensen Rømer (16441710) demonstrates the finite speed of light via observations of the eclipses of the satellites of Jupiter. While not calculating a speed for light, he estimates the SunEarth transit time for light to travel as roughly 11 minutes. 
Chirstiaan Huyghens 
1677  Christiaan Huyghens (162995) extends the wave theory of light in his work Treatise on Light, unpublished until 1690.  
1687  Newton (16421727) notes magnetism to be a nonuniversal force and derives an inverse cubed law for two poles of a magnet.  
1690  Publication of Huyghens' work Treatise on Light. This work includes a wave theory of light with a finite speed, giving the first numerical quote for the speed of light to be 2.3 x 10^{8} m/s (often mistakenly attributed to Rømer). The work also gives explanations of wave propagation, reflection, refraction, doublerefration, and polarization.  
1699  Nicolas Malebranche (16381715) proposes monochromatic light to depend on periodic vibrations and that brightness is in proportion to their amplitude.  
1704  Newton's research on light culminates in the publication of his Optics, describing light both in terms of wave theory and his corpuscular theory.  
1709  Francis Hauksbee's (16661713) PhysicoMechanical Experiments on Various Subjects.  
1728  James Bradley (16931762) discovers the phenomenon of steller aberration, confirming earlier suggestions by Rømer that the speed of light is finite.  
1729  Stephen Gray (ca 16701736) shows static electricity to be transported via substances, especially metals.  
1733  CharlesFrancois de Cisternai du Fay (16981739) discovers that electric charges are of two types and that like charges repell while unlike charges attract.  
1745  Ewald Kleist (17001748) invents the Leyden jar for storing electric charge.  
1746 
William Watson (171589) suggests conservation of electric charge.
Jean Antoine Nollet's Essai sur l'electricité des corps. 

1747 
Benjamin Franklin
(170690) proposes that electricity be modeled by a single fluid with two states of
electrification, materials have more or less of a normal amount of electric fluid,
independently proposing conservation of electric charge, and
introducing the convention of describing the two types of charges as positive and negative.
Watson passes electrical charge along a two mile long wire. 

1750  John Michell (172493) demonstrates that the action of a magnet on another can be deduced from an inverse square law of force between individual poles of the magnet, published in his work, A Treatise on Artificial Magnets.  
1759  Franz Ulrich Theodosius Aepinus (17241802) publishes An Attempt at a Theory of Electricity and Magnetism, the first book applying mathematical techniques to the subject.  
1764  Johannes Wilcke invents the electrophorus, a device which can produce relatively large amounts of electric charge easily and repeatedly. (See Links)  
1766  Joseph Priestley (17331804) deduces the inverse square law for electric charges using the results of experiments showing the absence of electrical effects inside a charged hollow conducting sphere.  
1772  Henry Cavendish publishes, "An Attempt to Explain some of the Principal Phenomena of Electricity, by Means of an Elastic Fluid."  
1775  Alessandro Guiseppe Antonio Anastasio Volta (17451827) invents an electrometer, a plate condenser and the electrophorus. 
Charles de Coulomb 
1777  Charles Augustin de Coulomb's (17361806) research sets a new direction in research into electricity and magnetism.  
early 1780s 
Luigi Galvani (173798) uses the response of animal tissue to begin studies of electrical currents produced by chemical action rather than from static electricity. The mechanical response of animal tissue to contact with two dissimilar metals is now known as galvanism.  
1785  Coulomb independently invents the torsion balance to confirm the inverse square law of electric charges. He also verifies Michell's law of force for magnets and also suggests that it might be impossible to separate two poles of a magnet without creating two more poles on each part of the magnet.  
1799  Volta shows that galvanism is not of animal origin but occurred whenever a moist substance is placed between two metals. This discovery eventually leads to the "Volta pile" a year later, the first electric batteries.  
1800  Volta writes a paper on electricity by contact.  
1801 
Thomas Young's (17731829)
work on interference revives interest in the wave theory
of light. He also accounts for the recently discovered phenomenon of light
polarization by suggesting that light is a vibration in the aether transverse to the
direction of propagation.
Johann Georg von Soldner (17761833) makes a calculation for the deflection of light by the sun assuming a finite speed of light corpuscles and a nonzero mass. (The result, 0.85 arcsec, was rederived independently by Cavendish and Einstein (1911), but went unnoticed until 1921. ) 

1807  H Davy's lecture, "On Some Chemical Agents of Electricity," drawing close the possible relationships of chemical and electrical forces.  
1812  SimeonDenis Poisson (17811840) formulates the concept of macroscopic charge neutrality as a natural state of matter and describes electrification as the separation of the two kinds of electricity. He also points out the usefulness of a potential function for electrical systems.  
1813  Measurements of specific heat of air as a function of pressure by Delarache and Bérard.  
1814  Augustin Jean Fresnel (17881827) independently discovers the interference phenomena of light and explains its existence in terms of wave theory. 
André Marie Ampère 
1817  Fresnel predicts a dragging effect on light in the aether.  
1818  Fresnel's essay on optics and the aether.  
1820 
(July 21) Hans Christian Oersted (17771851) notes the deflection of a magnetic compass
needle caused by an electric current after giving a lecture demonstration. Oersted
then demonstrates that the effect is reciprocal.This initiates the unification
program of electricity and magnetism.
July 27, André Marie Ampère (17751836) confirms Oersted's results and presents extensive experimental results to the French Academy of Science. He models magnets in terms of molecular electric currents. His formulation inaugurates the study of electrodynamics independent of electrostatics. Fall, JeanBaptiste Biot (17741862) and Felix Savart (17921841) deduce the formula for the strength of the magnitec effect produced by a short segment of current carrying wire. 

1825  Ampère 's memoirs are published on his research into electrodynamics.  By the 1820's, the concept of a luminiferous ether comes into common use by physicists and engineers. 
1827  Georg Simon Ohm (17891854) formulates the relationship between current to electromotive force and electrical resistance.  
1828  George Green (17931841) introduces the notion of potential and formulates what is now called Green's Theorem relating the surface and volume distributions of charge. (The work goes unnoticed until 1846.)  
1831  Michael Faraday (17911867) begins his investigations into electromagnetism.  
1832  Gauss (17771855) independently states Green's Theorem without proof. He also reformulates Coulomb's law in a more general form, and establishes experimental methods for measuring magnetic intensities. 
Carl Friedrich Gauss 
1835  Gauss formulates separate electrostatic and electrodynamical laws, including "Gauss's law." All of it remains unpublished until 1867.  
1838 
Faraday
explains electromagnetic induction, electrochemistry and formulates
his notion of lines of force, also criticizing actionatadistance theories.
Wilhelm Eduard Weber (180491) and Gauss apply potential theory to the magnetism of the earth. 

1839  The potential theory for magnetism developed by Weber and Gauss extented to all inversesquared phenomena.  
1842  William Thomson (Lord Kelvin, 18241907) writes a paper, "On the uniform motion of heat and its connection with the mathematical theory of electricity," based on the ideas of Fourier. The analogy allows him to formulate a continuity equation of electricity, implying a conservation of electric flux.  
1845 to 1850 
Michael Faraday
introduces the idea of "contiguous magnetic action" as a local interaction,
instead of the idea of instantaneous action at a distance, using concepts now known as fields.
He also estabishes a connection between light and electrodynamics by
showing that the transverse polarization direction of a light beam was rotated about the
axis of propagation by a strong magnetic field (today known as "Faraday rotation").
G T Fechner proposes a connection between Ampère's law and Faraday's law in order to explain Lenz's law. 

1846 
Weber
proposes a synthesis of electrostatics, electrodynamics and induction using the
idea that electric currents are moing charged particles. The interactions are
instantaneous forces. Weber's theory contains a limiting velocity of electromagnetic
origin with the value Sqrt(2) * c.
William Robert Grove's (18111896) Correlation of physical forces The partialdrag theory of George Gabriel Stokes (18191903) is revived for the explanation of stellar aberration. 

1849  A.H.L. Fizeau begins experiments to determine the speed of light.  
1851  Fizeau's interferometry experiment confirming Fresnel's theoretical results.  
1852  Stokes names and explains the phenomena of fluorescence.  
1854  Bernhard Riemann (182666) makes unpublished conjectures about an 'investigation of the connection between electricity, galvanism, light and gravity.'  
1855  Weber and R Kohlrausch determine a limiting velocity which turns up in Weber's electrodynamic theory, and that it's value is about 439,450 km/s. 
James Clerk Maxwell 
1855 to 1868 
James Clerk Maxwell (183179) completes his formulation of the field equations of electromagnetism. He established, among many things, the connection between the speed of propagation of an electromagnetic wave and the speed of light, and establishing the theoretical understanding of light.  
1858  Riemann generalizes Weber's unification program and derives his results via a solution to a wave function of a electrodynamical potential (finding the speed of propagation, correctly, to be c). He claimed to have found the connection between electricity and optics. (Results published postumously in 1867.)  
1861 
Riemann
uses Lagrange's theorem to deal with velocitydependent electrical accelerations.
Gustav Robert Kirchhoff (18241887) formulates the model of the black body. 
Bernhard Riemann 
1863  John Tyndall's Heat Considered as a Mode of Motion.  
1864  Maxwell publishes A Dynamical Theory of the Electromagnetic Field, his first publication to make use of his mathematical theory of fields.  
1865  Maxwell's A Dynamical Theory of the Electromagnetic Field, formulating an electrodynamical formulation of wave propagation using Lagrangian and Hamiltonian techniques, obtaining the theoretical possibility of generating electromagnetic radiation. (The derivation is independent of the microscopic structures which may underlie such phenomena.)  
1870  Hermann Ludwig Ferdinand von Helmholtz (182194) developes a theory of electricity and shows Weber's theories to be inconsistent with the conservation of energy.  
1873  The first edition of Maxwell's Treatise on Electricity and Magnetism is published.  
1874  George J Stoney estimates the charge of an electron to be about 10^{20} Coulombs and introduces the term "electron." 
Hendrik Lorentz 
1875 
Hendrik Antoon Lorentz
(18531928), in his doctoral thesis, derives the phenomena of reflection and refraction in terms of
Maxwell's theory.
W Crookes performs experiments on cathode rays. 

1879  Maxwell suggests that an earthbased experiment to detect possible aether drifts could be performed, but that it would not be sensitive enough.  
1881 
A.A. Michelson begins his interferometry experiments to detect a luminiferous aether.
Joseph John Thomson's (18561940) paper, "On the electric and magnetic effects produced by the motion of electrified bodies" explores inertial effects due to displacement currents. 

1884 
Heinrich Rudolf Hertz (185794) develops a reformulation of electrodynamics and shows
his and
Helmholtz's
theories both amount to
Maxwell's theory.
John Henry Poynting (18521914) establishes a principle of electromagnetic radiation energy which can be localized and flow (the first such energy localization principle established); not confined to existing only in conductors, but throughout space, independent of matter. 

1885 to 1887 
Oliver Heaviside (18501925) writes Electromagnetic induction and its propagation over the course of two years, reexpressing Maxwell's results in 3 (complex) vector form, giving it much of its modern form and collecting together the basic set of equations from which electromagnetic theory may be derived (often called "Maxwell's equations"). In the process, He invents the modern vector calculus notation, including the gradient, divergence and curl of a vector. 
Oliver Heaviside 
1887 
Heinrich Rudolf Hertz experimentally produces electromagnetic radiation with radio waves
in the GHz range, also discovering the photoelectric effect and predicting that gravitation would also have
a finite speed of propagation.
W Voight, working through an analysis of Doppler effects using an elastic model of the luminiferous aether to describe optical properties, produces a set of relations between space and time intervals which are later rediscovered independently by Lorentz and now knows as the "Lorentz equations" (first socalled by Poincaré in 1904). 

1889 
George Francis FitzGerald (18511901)
suggests that bodies contract in the direction of motion against the luminiferous aether by an amount
which would account for the null results coming from the MichelsonMorley experiments on aether motion.
(A more detailed calculation is performed independently by
Lorentz in 1895.)
FitzGerald also suggests that the speed of light is an upper bound on any possible speed.
(This suggestion reappears in 1900 by Lorentz, in 1904 by Poincaré, and again in 1905 by Einstein.)
John William Strutt (Lord Rayleigh, 18421919) presents a model for radiation in terms of wave propagation. Heaviside's "On the electromagnetic effects due to the motion of electrification through a dielectric," proposes part of inertial mass to be electromagnetic in origin and includes dependencies on higherorder terms in (v/c). 

1890  Hertz publishes his memoirs on electrodynamics, simplifying the form of the electromagnetic equations, replacing all potentials by field strengths, and deduces Ohm's, Kirchoff's and Coulomb's laws. 
JJ Thomson 
1892 to 1904 
Lorentz completes the description of electrodynamics by clearly separating electricity and electrodynamic fields and formulating the equations for charged particles in motion.  
1893  Wilhelm Carl Werner Otto Fritz Franz Wien (18641928) gives his displacement law of blackbody radiation.  
1896 
Wien theoretically derives
the radiation distribution law.
Discovery of Xrays and Becquerel radiation. Discovery of the Zeeman effect. 

1897  JJ Thomson experimentally determines the chargetomass ratio, e/m, of electrons.  
1898  Jules Henri Poincaré (18541912) suggests that a complete measurement theory must formulate a notion of distant synchronization and discusses its relevance to the apparent constancy of the speed of light.  
1899 
Lorentz refines the transformation
laws, formulating the notion of local time and local coordinate systems in electrodynamics.
Thomson and Philipp Lenard begin experimental investigations of photoelectric radiation. 
Hermann Minkowski 
1900 
Wien's
"On the possibility of an electromagnetic foundation of mechanics."
Poincaré's paper "The theory of Lorentz and the principle of reaction," showing electromagnetic radiation to have a momentum proportional to a field's Poynting vector, and that the momentum of a recoiling body to be vE/c^{2}. Max Karl Ernst Ludwig Planck (18581947), studying blackbody radiation derives the correct radiation spectrum for blackbodies. Planck proposes the constant, h (Planck's constant), as a quantum of action in phase space. 

1902 
Max Abraham's (18751922)
"The dynamics of electrons," also introducing the concept of electromagnetic momentum.
Walter Kaufmann (18711947) performs experiments on the deflection of electrons by electric and magnetic fields and a determination of the ration e/m; In a second paper, he concludes that the mass of an electron is purely electromagnetic in origin. 

1903  Abraham's "Principles of the dynamics of electrons," attempts to show, among other things, the electromagnetic foundation of mechanics.  
1904  Poincaré uses light signals as a functional technique to establish distant synchronization in application to Lorentz's electron theory, also putting forth the first formulation of a principle of electrodynamic relativity.  
1905 
Albert Einstein
(18791955) analyzes the phenomena of the photoelectric effect and theorizes
that light may be taken to be made up of vast amounts of packets of electromagnetic
radiation in discrete units.
Einstein publishes several papers drawing out the symmetries of Maxwell, Hertz and Lorentz's electromagnetic theory, the underlying connection in measurement theory and the status of the electromagnetic aether. 

1907 
Hermann Minkowski
(18641909), through considerations of the group properties of the equations of electrodynamics, reinterprets
Einstein's
relativity theory as a kind of geometry of spacetime, considered as a single medium.
Planck gives a corrected derivation of the massenergy relation using Poincaré's radiation momentum. 

1908  Gilbert N Lewis (18751946) publishes "A revision of the fundamental laws of matter and energy," deriving dE = c^{2}dm from considerations of radiation pressure.  
1933  Experiments by Patrick Blackett (18971974) and Giuseppe Occhialini (190793) on pair production demonstrate the complete annihilation of matter into electromagnetic energy. 
Sources: 
Bellone, Enrico,
A
World on Paper: Studies on the Second Scientific Revolution, 1980, ISBN 0262021471, QC7.B4313
Brush, Stephen G, Statistical Physics and the Atomic Theory of Matter From Boyle and Newton to Landau and Onsager Doughty, Noel A, Lagrangian Interaction: An Introduction to Relativistic Symmetry in Electrodynamics & Gravitation, 1990, ISBN 0201416255 Gans, Paul J, The Medieval Technology Pages: Magnets, 1998 Jammer, Max, Concepts of Mass in Classical and Modern Physics, 1961, ISBN 0486299988 Lindberg, David C, (ed.) Science in the Middle Ages, 1978 Stauffer, Robert C, "Speculation and Experiment in the Background of Oersted's Discovery of Electromagnetism," Isis, 48, pp 3550. Nobel Prizes in Physics The great MacTutor History of Mathematics Archive 
Links: 
Electromagnetism and Classical Optics
Electrophorus and Accessories A Timeline of Electricity and Magnetism 
Notes: 
