Text: "The time period of a penduluum with a moveable weight is most easil ascertained by experiment and not by calculation. Theoretically, in the case of a "simple" penduluum - that is, an imaginary penduluum without weight except at the bob - the period of oscillation varies inversely as the square root of the length, i.e., if the length be increased four-fold, the time period will be one half what it was before. A simple penduluum does notm however, exist practically, and though the law above ennunciated may serve to give a general idea of the lengths corresponding to differen time periods, these are really only to be arrived at with accuracy by trial." [Harmonic Vibrations and Vibration Figures, page 37]

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