Though James Clerk Maxwell (1831–1879) is best remembered for his epochal achievements in electricity and magnetism, he was wide-ranging in his scientific investigations, and he came to brilliant conclusions in virtually all of them. As James R. Newman put it, Maxwell "combined a profound physical intuition, an exquisite feeling for the relationship of objects, with a formidable mathematical capacity to establish orderly connections among diverse phenomena. This blending of the concrete and the abstract was the chief characteristic of almost all his researches." Maxwell's work on heat and statistical physics has long been recognized as vitally important, but Theory of Heat, his own masterful presentation of his ideas, remained out of print for years before being brought back in this new edition. In this unjustly neglected classic, Maxwell sets forth the fundamentals of thermodynamics clearly and simply enough to be understood by a beginning student, yet with enough subtlety and depth of thought to appeal also to more advanced readers. He goes on to elucidate the fundamental ideas of kinetic theory, and — through the mental experiment of "Maxwell's demon" — points out how the Second Law of Thermodynamics relies on statistics. A new Introduction and notes by Peter Pesic put Maxwell's work into context and show how it relates to the quantum ideas that emerged a few years later. Theory of Heat will serve beginners as a sound introduction to thermal physics; advanced students of physics and the history of science will find Maxwell's ideas stimulating, and will be delighted to discover this inexpensive reprint of a long-unavailable classic.