For this edition I have added one new topic, made a number of miscellaneous changes intended to improve the presentation and clarify some of the arguments, and adjusted a few emphases to attune with the changing times. (Microwave ovens are now commonplace, while ballistic galvanometers have been consigned to the laboratory basement.) To keep the length reasonable I have relegated to the problems a few peripheral topics, such as Lorentzians.

The teaching of vibrational physics at undergraduate level cannot ignore for ever the revolutionary ideas grouped under the title ‘chaos’. I believe that a straightforward description of the physical phenomena will provide the student with a platform from which to approach the more detailed, but also more abstract, consideration of these matters in terms of trajectories and attractors in phase space. I have therefore expanded chapter 7 to include a simple discussion of large-amplitude forced vibrations, introducing chaotic vibrations and related non-linear effects.