In the early stages of development of every form of transport, the pioneers have cheerfully undergone great extremes of discomfort and unpleasantness. As the sense of novelty and adventure began to lose its early appeal a slow but insistent demand for greater comfort arose. To-day, there is a growing tendency to take aeronautics as a matter of course, and an increasing demand for those standards of comfort which have become the rule in the older methods of transport.

The two factors that most seriously prejudice one's comfort in aerial transport are probably noise and vibration. The problem of aircraft noise was laid before you last session by Dr. Davies.

The engineer has seldom a good word to say for vibration. In all his schemes it comes to cross him like an ill-tempered fairy godmother. In the days when men designed by eye and worked in tenths of an inch instead of in thousandths, vibration was more of a nuisance than a serious problem. To-day, when factors of safety are being pared to the bone, when weight is regarded with a jealous eye and members are being stressed right up to the limits of their capacity—to-day, vibration is rapidly becoming a definite limiting factor in design, and the problem of vibration in all its varied forms, one of the most pressing that the engineer has to face.