The physics, or natural philosophy, of music has fascinated scholars and scientists since ancient times: from Pythagoras' concept of celestial harmony, to the work of Galileo, Mersenne, Euler and Ohm, culminating in the nineteenth century with Helmholtz's definitive work On the Sensations of Tone. William Pole (1814–1900) was a civil engineer and musicologist. He was elected a Fellow of the Royal Society in 1861 and was a founder member of the Royal Musical Association. First published in 1879, this work brings together his series of lectures on the theory of music, from the nature of sound to the physics of harmony, given in 1877 at the invitation of the Royal Institution. They were intended as an introduction to Helmholtz's research for the student or lay person, and include discussions of sound, scales, intervals, harmony and counterpoint (covering both historical and theoretical aspects), all illustrated with musical examples.