There is no branch of classical physics that is older in its origins and yet more modern in its applications than that of acoustics. As long ago as the time of Galileo, quantitative experiments were performed on the vibrations of strings and the sound that is so produced. Boyle, Hooke, and Newton were interested in sound, and Newton undertook to compute, theoretically, its speed. Later on, the great mathematicians Laplace, Euler, d'Alembert, Bernoulli, Lagrange, and Poisson laid the bases for what was to become the general subject of hydrodynamics, although there was a great scarcity of experimental data with which to test their conclusions. In the nineteenth century, the results of the experiments of Doppler, Kundt, Kelvin, and others added to the growing body of the subject. Helmholtz, that Leonardo da Vinci of modern times, wrote his monumental work, the Sensations of Tone, largely from the physiological approach. Late in the nineteenth and during the early twentieth century, finishing touches to the already elegant formulation of  the mechanics of sound propagation were added by Rayleigh and Lamb, whose writings on the subject have become "standard" treatises.