Early life Franz Ernst Neumann was born in
Joachimsthal,
Margraviate of Brandenburg (near
Berlin), the son of Ernst Neumann, a farmer who became a state agent. His mother was a Countess who was not allowed to marry Ernst, and Neumann did not meet her mother until he was 10 years old. In 1845, Neumann introduced the
magnetic vector potential to discuss
Ampère's circuital law. Later, Neumann attacked the problem of giving mathematical expression to the conditions holding for a surface separating two crystalline media, and worked out from theory the laws of double refraction in strained crystalline bodies. He also made important contributions to the mathematical theory of electrodynamics, and in papers published in 1845 and 1847, established mathematically the laws of the induction of electric currents. His last publication, which appeared in 1878, was on
spherical harmonics (
Beiträge zur Theorie der Kugelfunctionen). With the mathematician
Carl Gustav Jacobi, he founded in 1834 the
Mathematisch-physikalisches Seminar which operated in two sections for mathematics and for
mathematical physics. Not every student took both sections. In his section on mathematical physics Neumann taught mathematical methods as well as the techniques of an exact experimental physics grounded in the type of precision measurement perfected by his astronomer colleague
Friedrich Wilhelm Bessel. The objective of his seminar exercises was to perfect one's ability to practice an exact experimental physics through the control of both constant and random experimental errors. Only a few students actually produced original research in the seminar; a notable exception was
Gustav Robert Kirchhoff who formulated
Kirchhoff's laws on the basis of his seminar research. This seminar was the model for many others of the same type established after 1834, including Kirchhoff's own at
Heidelberg University. Neumann retired from his professorship in 1876, and died at
Königsberg (now
Kaliningrad,
Russia) in 1895 at the age of 96. == Children ==