The five fundamental criteria of the performance of a motor vehicle as a whole are stated. Riding comfort is investigated at length with a view to determining methods of measurement of the two classes of vehicle vibrations that affect the riding qualities of a car, so that suitable springs can be designed to overcome them. The underlying principles of the seismograph are utilized in designing a specialized form of this instrument for measuring vehicle vibrations, the general design considerations are stated and a detailed description is given. This is followed by an explanation of the methods used in analyzing the curves obtained, thus making possible a standardized measurement of riding comfort. The factors determining riding comfort are then analyzed in connection with spring-development work, the most important are summarized and the preliminary experimental results of those directly determined by the seismograph are outlined. The forced and the free oscillations of a vehicle body are mathematically analyzed in Appendix I. Two theorems are developed in Appendix II; one for stiffness and the other for static deflection of lever-suspension springs.
