A monochord is a single string device with an adjustable bridge thus allowing two pitches to be heard simultaneously on either side of the bridge. Pythagoras' most important work is his study of the ratio of these string lengths. This study led to the development of traditional harmony and the major scale.
These ratios are referred to as the "musical ratios". Applications of the musical ratios can be found in art and architecture. [more info by Paul Calter]
