1850
Magnetic susceptibility

1850
Electricity & the body
French physician Guillaume Benjamin Armand Duchenne publishes information on his long-running study on facial muscles and their expression of emotion, discoveries made from applying electrical stimulus directly to or through the skin.
1851
Thermoelectricity
William Thomson (Lord Kelvin) publishes his general theory of thermoelectricity.
1852
Sunspots & magnetism
Edward Sabine, an English astronomer, discovers a correlation between the sunspot cycle and magnetic activity on Earth.
1853
RLC circuit theory
William Thomson (Lord Kelvin) derives the formula for magnetic energy and develops a theory of the RLC circuit.
1853
Animal electricity
German physicist Hermann von Helmholtz's work with electricity and muscle tissue leads him to publish "Some laws concerning the distribution of electric currents in conductors with applications to experiments on animal electricity." This work includes a mathematical demonstration of what is now known as Thévenin's theorem of electric circuits.
1853
Alliance Company
The Alliance Company is founded in Paris as a manufacturer of machines for generating electric current, which are originally intended for use by researchers carrying out work in electrochemistry.
1855
Maxwell's first essay

1856
Discoveries in Germany
German physicists Wilhelm Weber and Rudolf Kohlrausch measure the ratio of electrostatic to electromagnetic units and find that the quantity is analogous to the value of the speed of light accepted at that time.
1857
Signals through wire
Physicist Gustav Kirchhoff expands on the work of compatriots Weber and Kohlrausch, demonstrating that electromagnetic signals can be transmitted on a highly conductive wire at the speed of light.
1858
Bending cathode rays
Julius Plücker, a German physicist and mathematician, discovers that magnetic forces can cause the bending of cathode rays.
1858
Transatlantic cable

1858
Arc lighting
The first practical arc lighting system is installed in a lighthouse in England.
1859
Rechargeable battery
French physicist Gaston Planté builds the first rechargeable battery from two lead sheets rolled into a cylinder, submerged in a diluted sulfuric acid solution, and then charged.
1861
Lines of force
James Clerk Maxwell publishes his paper On Physical Lines of Force, in which he discusses the lines of force in mechanical terms.
1861
Transcontinental telegraph
The first transcontinental telegraph line is completed in America.
1861
First phone
German physics professor Johann Philipp Reis describes in a lecture an electric device he constructed that he dubbed the telephone. However, Reis's invention is unable to sufficiently reproduce most sounds, including human speech, and is never patented or further developed by him.
1864
Units of force
The Committee on Electrical Standards of the British Association for the Advancement of Science completes a report defining units of electromotive force and resistance based on millimeters, grams and seconds (mgs system). Less than 10 years later the group would recommend switching to a centimeter, gram and second (cgs) system.
1864
Maxwell's equations
The entire set of James Clerk Maxwell's electromagnetism equations appears in his paper On a Dynamical Theory of the Electromagnetic Field.
1866
Leclanché cell

1867
Lorenz's theory
Danish physicist Ludwig Lorenz independently develops an electromagnetic theory of light and shows that James Clerk Maxwell's equations can be derived from his scalar and vector potentials, though he disagrees with Maxwell's belief that ether was a necessary medium for the transmission of light.
1869
Gramme dynamo
