Most symphonic instruments were standardized in the eighteenth and nineteenth centuries, but the design of the clarinet is still changing. O. Lee Gibson begins this first complete study of its acoustical principles with a history of the clarinet, a survey of the instruments of famous clarinetists, and the characteristics of the national schools of clarinet manufacture. He then describes the modal frequency ratios of a clarinet and the timbres of its tones, as well as its dynamic range, stability, flexibility, and responsiveness. He stresses that all the dimensions of a wind instrument - length, volume, size, weight, and material - are interrelated. He concludes with a discussion of existing but rarely available mechanical improvements and suggests other acoustical enhancements that have not been fully utilized.