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Measuring Earthquakes1

Nature volume 30, pages 174177 | Download Citation



II.—RESULTS. IN this paper a short account will be given of the chief results of two and a half years' observations in the Seismological Observatory of the University of Tokio. The first instruments to be successfully used were the horizontal pendulum, or rather a pair of horizontal pendulums writing a multiplied record of two rectangular horizontal components of the earth's motion on a revolving plate of smoked glass, and also a very long common in amplitude and in period the successive waves were far from equal. A rough idea of the greatest velocity and greatest acceleration was, however, obtained by treating the greatest movement as a simple harmonic vibration, with a period of three-fifths of a second. This gave 1.6 mm. per second for the greatest velocity, and 16.4 mm. per second per second for the greatest acceleration, showing that bodies attached rigidly to the earth's surface must have experienced a horizontal force equal to about one-six-hundredth of their own weight. In three of the five earth-pendulum. The duplex pendulum, an astatic verticalmotion seismograph, and other instruments which have been mentioned in the former article, were added later.1


  1. 1.

    Described in the Transactions of the Asiatic Society of Japan, vol. ix. p. 40.

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  1. University College, Dundee

    • J. A. EWING


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