[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