James Clerk Maxwell (1831-1879), the Scottish physicist,
did revolutionary work in electromagnetism and
the kinetic theory of gases.
He formulated,
independently of Ludwig Boltzmann, the Maxwell-Boltzmann
kinetic theory of gases.
Maxwell showed that a few
relatively simple mathematical equations could express the
behavior of electric and magnetic fields and their interrelated
nature. These four partial differential equations
first appeared in fully developed form in Electricity and
Magnetism (1873). Since known as Maxwell's equations they are one
of the great achievements of 19th-century physics.