"An elongated uniform body, e.g., a dressed lath of pine, has three primary centers - the center of gravity, the center of oscillation, and the center of velocity. The center of gravity is the center of the body; the center of oscillation is two-thirds from the end as the point of suspension; the center of velocity is at two-thirds of one-third from the end; i.e., at two-ninths from the end as the point of suspension.
"This elongated body suspended at the end, or at one-third from the end, the oscillations are the same. The one-third above the point of suspension so balances the two-thirds below that the oscillations are performed in the same time for both suspensions. When it is suspended at two-thirds of the one-third. i.e., one-ninth of the whole length above the center of oscillation, one-ninth above balances two-ninths below; the oscillating part is thus, as it were, one-ninth shorter than at the center of oscillation, and gives rise to the center of velocity." [Scientific Basis and Build of Music, page 92-93]
"A point on a pendulum two-thirds of one third the length of the string, i.e., suspension from which point giving the highest rate of vibration." Ramsay, Dougald Carmichel; [Scientific Basis and Build of Music; Marcus Ward & Co., Ltd., New York, 1893.]