The forced resonant vibrations of a long column of Quincy granite have been studied with the object of discovering the effect of frequency upon the velocities of elastic waves. Longitudinal, flexural, and torsional modes were used, covering the frequency range 140-4500 cycles per second. For these frequencies the velocities were independent of frequency to within 1 per cent or less. The internal friction was also roughly independent of frequency, with Q = 150. The damping of seismic waves is considered with reference to these results.

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