Both historical treatment and critical analysis, this work by a noted physicist takes a fascinating look at a fundamental of physics, tracing its development from ancient to modern times.

The first models for an electromagnetic theory of dispersion are presented and an attempt is made to demonstrate the important role played by study of this phenomenon at the end of the nineteenth century. As well as indicating the need to have a better understanding of the microscopic properties of matter, dispersion also contributed to the discussion over the nature of X-rays and was fundamental for introduction of Lorentz's electron theory.