Читать книгу A Study of Recent Earthquakes - Charles Davison - Страница 26

[3] Irish Acad. Trans., vol. xxi., 1848, pp. 51–105 (read Feb. 9, 1846).

[4] Brit. Assoc. Reports, 1850, pp. 1–87; 1851, pp. 272–330; 1852, pp. 1–176; 1853, pp. 117–212; 1854, pp. 1–326; 1858, pp. 1–136.

[5] A Manual of Scientific Enquiry, edited by Sir J.F.W. Herschel, 1849, pp. 196–223.

[6] Irish Acad. Trans., vol. xxii., 1855, pp. 397–410.

[7] The linear dimensions of the isoseismal lines are obtained by measurements from Mallet's maps. The areas are given by him in geographical square miles.

[8] Mallet, by some accident, omitted the losses at Polla and neighbouring towns from this estimate. Mercalli (Geologia d'Italia, pte. 3, p. 324) gives the number of killed as more than 12,300.

[9] Mallet does not make use of the term epicentre; he speaks of the line FE as the seismic vertical. The modern and accepted terms are used above.

[10] Japan Seismol. Soc. Trans., vol. xi., 1887, pp. 175–177.

[11] Ital. Seismol. Soc. Boll., vol. ii., 1896, pp. 180–188.

[12] Professor Omori gives the mean direction as S. 71° W., but this was obtained from observation on lamps with square, as well as with circular bases.

[13] Twelve measurements chosen at random from Professor Omori's list gave a mean direction of S. 78° W.

[14] When the accuracy of all the observations seemed equally probable, he adopted the mean of the two extremes as the true direction.

[15] If a be the amplitude of a simple harmonic vibration, T its complete period, v its maximum velocity, and f its maximum acceleration, we have v = 2πa ÷ T and f = 4π²a ÷ T²

[16] Earthquakes and other Earth Movements, pp. 81–82.

[17] Obtained from the formula: T = 2πa ÷ v = 2πx ⅓ ÷ 12

[18] If we take the maximum velocity to be 12 feet per second, and the period to be one second, the amplitude would be about 11½ inches.

[19] Vol. ii., p. 299. The punctuation of the original is not followed in the above extract.

[20] British Association Report, 1851, pp. 272–320.