Edward Sabine, an English astronomer, discovers a correlation between the sunspot cycle and magnetic activity on Earth.
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.
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.
Scottish physicist James Clerk Maxwell writes his first essay related to electricity, On Faraday's Lines of Force, in which he relates Faraday's conception of lines of force to the flow of a liquid and uses analytical mathematics to derive equations for electric and magnetic phenomena.
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.
Julius Plücker, a German physicist and mathematician, discovers that magnetic forces can cause the bending of cathode rays.
The first transcontinental telegraph line is completed in America.
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.
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.
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.