From the 1983 lecture programme:
Vibration is a very familiar phenomenon. Our hearts beat, our arms swing and we respond to air vibrating in our ears. In the world of machines, major advances have been made by engineers in recent times not only in the understanding of mechanical vibration but also in reducing it in practice. As the speed and the performance of machines continue to increase, the subject is becoming of increasing importance. Hardly any moving part is now made without some consideration of vibration and, in cases where life and limb are at risk, it is vital. We shall explore the different types of vibration to which machines and structures are susceptible, and we shall investigate how their natural tendency to vibrate can be countered.