Published online by Cambridge University Press: 01 May 2009
WHILE Michell's interest in geology lasted until at least 1788, he made no further known contribution to the study of earthquakes. He must have been aware of the disastrous Calabrian earthquakes of 1783, but he would no doubt regard them as timely illustrations of his theory. The eighty years which followed 1760 were, indeed, somewhat barren as regards the progress of seismology. Among the more important contributions during this period were Dolomieu's report on the Calabrian earthquakes of 1783, Darwin's memoir on the connexion of certain volcanic phenomena in South America (1838), and the well-known chapters in Lyell's Principles of Geology (1830).
page 241 note 1 Edin. New Phil. Journ., vol. xxxi, 1841, pp. 92–122, 259–309; vol. xxxii, 1842, pp. 106–27, 362–78; vol. xxxiii, 1842, pp. 372–88; vol. xxxiv, 1843, pp. 85–107; vol. xxxv, 1843, pp. 137–60; vol. xxxvi, 1844, pp. 72–86, 362–77.Google Scholar
page 242 note 1 It is interesting to notice that the possibility of a lunar periodicity occurred to Darwin in 1840. Writing to D. Milne, he remarks, “On the hypothesis of the crust of the earth resting on fluid matter, would the influence of the moon (as indexed by the tides) affect the periods of the shocks, when the force which causes them is just balanced by the resistance of the solid crust?” (More Letters of Charles Darwin, vol. ii, 1903, p. 115).
page 243 note 1 Roy. Soc. Proc., vol. xxxiii, 1882, pp. 20. For the above biographical details I am chiefly indebted to notices in Engineering, vol. lii, 1881, pp. 352–3, 371–2, 389–90; and Min. of Proc. of Inst. of Civ. Eng., vol. lxviii, 1882, pp. 297–304.Google Scholar
page 243 note 2 Other, and perhaps more probable, explanations of the movement are given in Trans. Seis. Soc. Japan, vol. i, pt. ii, 1880, pp. 31–5, and Geol. Mag., 1882, p. 264.Google Scholar
page 243 note 3 “On the Dynamics of Earthquakes; being an attempt to reduce their observed phenomena to the known laws of wave motion in solids and fluids” (read 02 9, 1846): Trans. Irish Acad., vol. xxi, 1848, pp. 51–105.Google Scholar
page 244 note 1 Many earlier writers had regarded earthquakes as due to the passage of waves of vibration, e.g. J. Michell in 1760, Thomas Young in 1807 (Lectures on Natural Philosophy, vol. i, p. 717), and D. Milne in 1841 (Edln. New Phil. Journ., vol. xxxi, pp. 262, 275–7). In his report on the theories of elevation and earthquakes (Rep. Brit. Assoc., 1847, pp. 33–92), W. Hopkins, treating the theory as obvious or well known, gives an account of wave-motion in solids and liquids that may still be read with advantage.
page 246 note 1 Rep. Brit. Assoc., 1851, pp. 272–317; Phil. Trans., 1861, pp. 655–79; 1862, pp. 663–76. The above velocities are given to the nearest foot per second. Mallet expresses them to three places of decimals. Such detail, however, is meaningless, for an error of one-hundredth of a second in the time of transit at Killiney Bay involves an error of more than 2 feet per second in the velocity.Google Scholar
page 246 note 2 Rep. Brit. Assoc., 1852, pp. 1–176; 1853, pp. 118–212; 1854, pp. 1–326; 1858, pp. 1–136.Google Scholar
page 248 note 1 Rep. Brit. Assoc., 1841, p. 48; 1842, pp. 96–7; 1843, p. 121; Edin. Neiv Phil. Journ., vol. xxxi, 1841, pp. 276–7.Google Scholar
page 249 note 1 Rep. Brit. Assoc., 1847, pp. 82–3.Google Scholar
page 250 note 1 A more detailed account of Mallet's investigation is given in my Study of British Earthquakes (Contemporary Science Series), pp. 7–44.Google Scholar