Still less can we conceive, however faintly, the number of elemental slips that constitute the history of a single fault. We may think, if we please, of the 143 tremors and earth-sounds noted at Comrie in Perthshire during the last three months of 1839, of the 306 earthquakes felt in the Island of Zante during the year 1896, or the 1,746 shocks recorded at Gifu during thirty days in 1891; but we shall be as far as ever from realising the vast number of steps involved in the growth of a fault, let alone a mountain-chain. Yet, all over the land-surface of the globe, the crust is intersected by numberless faults, and hardly any portion is there in which some or many of these faults are not growing. One country, indeed, such as Great Britain, may have reached a condition of comparative stagnancy; the fault-slips are few and slight, and earthquakes in consequence are rare and generally inconspicuous. In another, like Eastern Japan and the adjoining ocean-bed, the movements are frequent, occasionally almost incessant, and few years pass without some great convulsion by which cities are wrecked and hundreds of human lives are lost. At such times, we magnify the rôle of earthquakes, and are in some danger of forgetting that, in the formation of a mountain-chain or continent, they serve no higher purpose than the creaking of a wheel in the complex movements of a great machine. FOOTNOTES: [79] _Phil. Trans._, vol. li., pt. ii., 1761, pp. 625-626. [80] _Journ. Sci. Coll. Imp. Univ._, Tokyo, vol. xi., 1899, pp. 194-195. [81] _Journ. Coll. Sci. Imp. Univ._, Tokyo, vol. vii., pt. v., 1894, pp. 1-4; _Ital. Sismol. Soc. Boll._, vol. ii., 1896, pp. 180-188. [82] _Journ. Coll. Sci. Imp. Univ._, Tokyo, vol. xi., 1899, pp. 161-195. [83] _Quart. Journ. Geol. Soc._, vol. lvi., 1900, pp. 1-7. [84] There is no reason why the surface-undulations of the Indian earthquake should not have produced a sensible shock even as far as Italy. Taking their amplitude in that country at 508 mm. and their period at 22 sec. (p. 283), the maximum acceleration would be about 40 mm. per sec., corresponding to the intensity 2 of the Rossi-Forel scale. (_Amer. Journ. Sci._, vol. xxxv., 1888, p. 429.) [85] _Nature_, vol. lii., 1895, pp. 631-633. [86] Gerland's _Beiträge zur Geophysik_, vol. iii., pp. 485-518. [87] _Phil. Trans._, 1900A, pp. 135-174. [88] _Publ. of Earthq. Inves. Com. in For. Langs._ (Tokyo), No. 4, 1900, pp. 47-67. [89] S.A. Papavasiliou, Paris, _Acad. Sci., Compt. Rend._, vol. cxix., 1894, pp. 112-114, 380-381. [90] _Geol. Mag._, vol. x., 1893, pp. 356-360. [91] _Geol. Soc. Trans._, vol. v., 1840, pp. 618-619. [92] The disturbed areas of these earthquakes contained, respectively, 221,000, 39,000, and 30,000 square miles. [93] _Boll. Sismol. Soc. Ital._, vol. viii., 1902, pp. 17-48. [94] _Roy. Soc. Proc._, vol. lvii., 1895, pp. 87-95. INDEX. Acceleration, maximum, of wave-motion in Japanese earthquake, 184, 185; in Indian earthquake, 272