Chapter XLIII: Appendix: I (4)

+----------------------------------------------------------------------+ | FOOTNOTES: | | | | [1] Trans. of Edin. Geol. Soc., vol. ii. p. 252. | | | | [2] Phil. Mag., January, 1863. | | | | [3] _Athenæum_, September 22, 1860. | | | | [4] Trans. Glasgow Geol. Soc., vol. iv., p. 313. | | | | [5] See Mr. Hopkin’s remarks on this theory, Quart. Journ. Geol. | | Soc., vol. viii. | | | | [6] See Chap. xxv. | | | | [7] See Chap. iv. | | | | [8] “Treatise on Astronomy,” § 315; “Outlines,” § 368. | | | | [9] _Annuaire_ for 1834, p. 199. Edin. New Phil. Journ., April, | | 1834, p. 224. | | | | [10] “Cosmos,” vol. iv. p. 459 (Bohn’s Edition). “Physical | | Description of the Heavens,” p. 336. | | | | [11] Phil. Mag. for February, 1867, p. 127. | | | | [12] The Gulf-stream at the narrowest place examined by the Coast | | Survey, and where also its velocity was greatest, was found to be | | over 30 statute miles broad and 1,950 feet deep. But we must not | | suppose that this represents all the warm water which is received | | by the Atlantic from the equator; a great mass flows into the | | Atlantic without passing through the Straits of Florida. | | | | [13] It is probable that a large proportion of the water | | constituting the south-eastern branch of the Gulf-stream is never | | cooled down to 40°; but, on the other hand, the north-eastern | | branch, which passes into the arctic regions, will be cooled far | | below 40°, probably below 30°. Hence I cannot be over-estimating | | the extent to which the water of the Gulf-stream is cooled down in | | fixing upon 40° as the average minimum temperature. | | | | [14] “Physical Geography of the Sea,” § 24, 6th edition. | | | | [15] “Physical Geography,” § 54. | | | | [16] Trans. of Roy. Soc. of Edin., vol. xxi., p. 57. Phil. Mag., § | | 4, vol. ix., p. 36. | | | | [17] “Smithsonian Contributions to Knowledge,” vol. ix. | | | | [18] “Heat as a Mode of Motion,” art. 240. | | | | [19] Trans. Roy. Soc. of Edin., vol. xxv., part 2. | | | | [20] See “Smithsonian Contributions to Knowledge,” vol. ix. | | | | [21] “Meteorology,” section 36. | | | | [22] _Comptes-Rendus_, July 9, 1838. Taylor’s “Scientific Memoirs,” | | vol. iv., p. 44 (1846). | | | | [23] The mean temperature of the Atlantic between the tropics and | | the arctic circle, according to Admiral Fitzroy’s chart, is about | | 60°. But he assigns far too high a temperature for latitudes above | | 50°. It is probable that 56° is not far from the truth. | | | | [24] The probable physical cause of this will be considered in the | | Appendix. | | | | [25] The mean temperature of the equator, according to Dove, is | | 79°·7, and that of the north pole 2°·3. But as there is, of course, | | some uncertainty regarding the actual mean temperature of the | | poles, we may take the difference in round numbers at 80°. | | | | [26] Trans. of Roy. Soc. Edin., vol. xxii., p. 75. | | | | [27] _Connaissance des Temps_ for 1863 (Additions). Lagrange’s | | determination makes the superior limit 0·07641 (Memoirs of the | | Berlin Academy for 1782, p. 273). Recently the laborious task of | | re-investigating the whole subject of the secular variations of the | | elements of the planetary orbits was undertaken by Mr. Stockwell, | | of the United States. He has taken into account the disturbing | | influence of the planet Neptune, the existence of which was not | | known when Leverrier’s computations were made; and he finds that | | the eccentricity of the earth’s orbit will always be included | | within the limits of 0 and 0·0693888. Mr. Stockwell’s elaborate | | Memoir, extending over no fewer than two hundred pages, will be | | found in the eighteenth volume of the “Smithsonian Contributions to | | Knowledge.” | | | | [28] When the eccentricity is at its superior limit, the absolute | | quantity of heat received by the earth during the year is, however, | | about one three-hundredth part greater than at present. But this | | does not affect the question at issue. | | | | [29] Scoresby’s “Arctic Regions,” vol. ii., p. 379. Daniell’s | | “Meteorology,” vol. ii., p. 123. | | | | [30] Tyndall, “On Heat,” article 364. | | | | [31] Tyndall, “On Heat,” article 364. | | | | [32] See Phil. Mag., March, 1870, p. | | | | [33] Captain Cook’s “Second Voyage,” vol. ii., pp. 232, 235. | | | | [34] “Antarctic Regions,” vol. ii., pp. 345−349. | | | | [35] Ibid., vol. i., p. 167. | | | | [36] Ibid., vol. ii., p. 362. | | | | [37] Edinburgh Philosophical Journal, vol. iv., p. 266. | | | | [38] Scoresby’s “Arctic Regions,” vol. i., p. 378. | | | | [39] Ibid., p. 425. | | | | [40] See Meech’s memoir “On the Intensity of the Sun’s Heat and | | Light,” “Smithsonian Contributions,” vol. ix. | | | | [41] “Antarctic Regions,” vol. i., p. 240. | | | | [42] _Challenger_ Reports, No. 2, p. 10. | | | | [43] See “Smithsonian Contributions,” vol. ix. | | | | [44] Quart. Journ. Geol. Soc., vol. xxv., p. 350. | | | | [45] Trans. of Glasgow Geol. Soc. for 1866. | | | | [46] _Revue des Deux Mondes_ for 1867. | | | | [47] Letter to the author, February, 1870. | | | | [48] “Révolutions de la Mer,” p. 37 (second edition). | | | | [49] Edin. Phil. Journ., vol. iv., p. 262 (1821). | | | | [50] Phil. Mag., § 4, vol. xxviii., p. 131. _Reader_, December 2nd, | | 1865. | | | | [51] This point will be found discussed at considerable length in | | the Phil. Mag. for September, 1869. | | | | [52] See Phil. Mag. for October, 1870, p. 259. | | | | [53] Proceedings of the Royal Society, No. 138, p. 596, foot-note. | | | | [54] The edition from which I quote, unless the contrary is stated, | | is the one published by Messrs. T. Nelson and Sons, 1870, which is | | a reprint of the new edition published in 1859 by Messrs. Sampson | | Low and Co. | | | | [55] “Physical Geography,” article 57. | | | | [56] Philosophical Magazine, vol. xii. p. 1 (1838). | | | | [57] “Mémoires par divers Savans,” tom. i., p. 318, St. | | Petersburgh, 1831. See also twelfth number of Meteorological | | Papers, published by the Board of Trade, 1865, p. 16. | | | | [58] Dubuat’s “Hydraulique,” tom. i., p. 64 (1816). See also | | British Association Report for 1834, pp. 422, 451. | | | | [59] See Proceedings of the Royal Society for December, 1868, | | November, 1869. Lecture delivered at the Royal Institute, _Nature_, | | vol. i., p. 490. Proceedings of the Royal Geographical Society, | | vol. xv. | | | | [60] Trans. of Glasgow Geol. Soc. for April, 1867. Phil. Mag. for | | February, 1867, and June, 1867 (Supplement). | | | | [61] Phil. Mag. for February, 1870. | | | | [62] “The Depths of the Sea,” pp. 376 and 377. | | | | [63] “The Threshold of the Unknown Region,” p. 95. | | | | [64] See “Physical Geography of the Sea,” chap. ix., new edition, | | and Dr. A. Mühry “On Ocean-currents in the Circumpolar Basin of the | | North Hemisphere.” | | | | [65] “Depths of the Sea,” _Nature_ for July 28, 1870. | | | | [66] “Memoir on the Gulf-stream,” _Geographische Mittheilungen_, | | vol. xvi. (1870). | | | | [67] Dr. Carpenter “On the Gulf-stream,” Proceedings of Royal | | Geographical Society for January 9, 1871, § 29. | | | | [68] Dr. Petermann’s _Mittheilungen_ for 1872, p. 315. | | | | [69] Proceedings of the Royal Society, vol. xvii., p. 187, xviii., | | p. 463. | | | | [70] The average depth of the Pacific Ocean, as found by the | | soundings of Captain Belknap, of the U.S. steamer _Tuscarora_, made | | during January and February, 1874, is about 2,400 fathoms. The | | depth of the Atlantic is somewhat less. | | | | [71] Proceedings of Royal Geographical Society, vol. xv., § 22. | | | | [72] It is a well-established fact that in polar regions the | | temperature of the sea decreases from the surface downwards; | | and the German Polar Expedition found that the water in very | | high latitudes is actually less dense at the surface than at | | considerable depths, thus proving that the surface-water could not | | sink in consequence of its greater density. | | | | [73] Proceedings of the Royal Society, vol. xix., p. 215. | | | | [74] _Nature_ for July 6, 1871. | | | | [75] Since the above objection to the Gravitation Theory of the | | Gibraltar Current was advanced three years ago, Dr. Carpenter | | appears to have abandoned the theory to a great extent. He now | | admits (Proceedings of Royal Geographical Society, vol. xviii., | | pp. 319−334, 1874) that the current is almost wholly due not to | | difference of specific gravity, but to an excess of evaporation in | | the Mediterranean over the return by rain and rivers. | | | | [76] Proceedings of Royal Society, No. 138, § 26. | | | | [77] Proceedings of Royal Geographical Society, January 9, 1871. | | | | [78] Ibid. | | | | [79] See §§ 20, 34; also Brit. Assoc. Report for 1872, p. 49, and | | other places. | | | | [80] See also to the same effect Brit. Assoc. Report, 1872, p. 50. | | | | [81] Phil. Mag. for Oct. 1871. | | | | [82] The actual slope, however, does not amount to more than 1 in | | 7,000,000. | | | | [83] Proc. of Roy. Geog. Soc., January 9, 1871, § 29. | | | | [84] Trans. of Geol. Soc. of Glasgow for April, 1867; Phil. Mag. | | for June, 1867. | | | | [85] _Nature_, vol. i., p. 541. Proc. Roy. Soc., vol. xviii., p. | | 473. | | | | [86] Chapter II. | | | | [87] Chapter II. | | | | [88] Chapter II. | | | | [89] Mr. Findlay considers that the daily discharge does not exceed | | 333 cubic miles (Brit. Assoc. Rep., 1869, p. 160). My estimate | | makes it 378 cubic miles. Mr. Laughton’s estimate is 630 cubic | | miles (Paper “On Ocean-currents,” Journal of Royal United-Service | | Institution, vol. xv.). | | | | [90] Proceedings of the Royal Geographical Society, vol. xviii., p. | | 393. | | | | [91] Phil. Mag. for October, 1871, p. 274. | | | | [92] Proceedings of the Royal Geographical Society, vol. xv. | | | | [93] Phil. Mag., February, 1870. | | | | [94] Brit. Assoc. Report, 1869, Sections, p. 160. | | | | [95] Journal of Royal United-Service Institute, vol. xv. | | | | [96] Dr. Carpenter (Proc. of Roy. Geog. Soc., vol. xviii., p. | | 334) misapprehends me in supposing that I attribute the Gibraltar | | current wholly to the Gulf-stream. In the very page from which he | | derives or could derive his opinion as to my views on the subject | | (Phil. Mag. for March, 1874, p. 182), I distinctly state that | | “the excess of evaporation over that of precipitation within the | | Mediterranean area would of itself produce a considerable current | | through the Strait.” That the Gibraltar current is due to two | | causes, (1) the pressure of the Gulf-stream, and (2) excess of | | evaporation over precipitation in the Mediterranean, has always | | appeared to me so perfectly obvious, that I never held nor could | | have held any other opinion on the subject. | | | | [97] Paper read to the Edinburgh Botanical Society on January 8, | | 1874. | | | | [98] Proc. Roy. Geog. Soc., vol. xviii., p. 362. A more | | advantageous section might have been chosen, but this will suffice. | | The section referred to is shown in Plate III. The peculiarity of | | this section, as will be observed, is the thinness of the warm | | strata at the equator, as compared with that of the heated water in | | the North Atlantic. | | | | [99] The temperature of column C in Dr. Carpenter’s section is | | somewhat less than that given in the foregoing table; so that, | | according to that section, the difference of level between column C | | and columns A and B would be greater than my estimate. | | | | [100] Captain Nares’s Report, July 30, 1874. | | | | [101] See Chapter IV. | | | | [102] Phil. Mag. for August, 1864, February, 1867, March, 1870; see | | Chap. IV. | | | | [103] Quarterly Journal of Science for October, 1874. | | | | [104] See a paper by M. Morlot, on “The Post-Tertiary and | | Quaternary Formations of Switzerland.” Edin. New Phil. Journal, New | | Series, vol. ii., 1855. | | | | [105] Edin. New Phil. Journ., New Series, vol. ii., p. 28. | | | | [106] Vogt’s “Lectures on Man,” pp. 318−321. | | | | [107] See Mr. Prestwich on Flint Implements, Phil. Trans. for 1860 | | and 1864. Lyell’s “Antiquity of Man,” Second Edition, p. 168. | | | | [108] Edin. New Phil. Journ., New Series, vol. ii., p. 28. | | Silliman’s Journ., vol. xlvii., p. 259 (1844). | | | | [109] Quart. Journ. Geol. Soc., vol. xxvii., p. 534. | | | | [110] Ibid., vol. xxviii., p. 17. | | | | [111] “Glacial Drift of Scotland,” p. 54. | | | | [112] “Glacial Drift of Scotland,” p. 58. | | | | [113] Quart. Journ. Geol. Soc., vol. v., p. 22. | | | | [114] “Glacial Drift of Scotland,” p. 64. | | | | [115] Trans. Edin. Geol. Soc., vol. ii., p. 391. | | | | [116] Trans. of Geol. Soc. of Glasgow, vol. iv., p. 146. | | | | [117] Geol. Mag., vi., p. 391. | | | | [118] See “Memoirs of Geological Survey of Scotland,” Explanation | | of sheet 22, p. 29. See also Trans. Glasgow Geol. Soc., iv., p. 150. | | | | [119] “Great Ice Age,” p. 374. | | | | [120] “Great Ice Age,” p. 384. | | | | [121] “Geological Survey of Ohio, 1869,” p. 165. See also “Great | | Ice Age,” chap. xxviii. | | | | [122] Quart. Journ. Geol. Soc., xxviii., p. 435. | | | | [123] Brit. Assoc. Report, 1863. | | | | [124] Trans. Glasgow Nat. Hist. Soc., vol. i., p. 115. | | | | [125] Trans. of the Geol. Soc. of Glasgow, vol. iii., p. 133. See | | also “Great Ice Age,” chaps. xii. and xiii. | | | | [126] Chap. XXIX. | | | | [127] Edin. New Phil. Journ., vol. liv., p. 272. | | | | [128] “Newer Pliocene Geology,” p. 129. John Gray & Co., Glasgow. | | | | [129] “Glacial Drift of Scotland,” p. 67. | | | | [130] “Glacial Drift of Scotland,” p. 12. | | | | [131] See Chapter IV. | | | | [132] “Discovery of the North-West Passage,” p. 213. | | | | [133] “Voyage of the _Resolute_,” p. 294. | | | | [134] Quart. Journ. Geol. Soc., vol. xi., p. 540. | | | | [135] “McClure’s North-West Passage,” p. 214. Second Edition. | | | | [136] “British Association Report for 1855,” p. 381. “The Last of | | the Arctic Voyages,” vol. i., p. 381. | | | | [137] Mr. James Geikie informs me that the great accumulations of | | gravel which occur so abundantly in the low grounds of Switzerland, | | and which are, undoubtedly, merely the re-arranged materials | | originally brought down from the Alps as till and as moraines | | by the glaciers during the glacial epoch, rarely or never yield | | a single scratched or glaciated stone. The action of the rivers | | escaping from the melting ice has succeeded in obliterating all | | trace of striæ. It is the same, he says, with the heaps of gravel | | and sand in the lower grounds of Sweden and Norway, Scotland and | | Ireland. These deposits are evidently in the first place merely the | | materials carried down by the swollen rivers that issued from the | | gradually melting ice-fields and glaciers. The stones of the gravel | | derived from the demolition of moraines and till, have lost all | | their striæ and become in most cases well water-worn and rounded. | | | | [138] Report on Icebergs, read before the Association of American | | Geologists, _Silliman’s Journal_, vol. xliii., p. 163 (1842). | | | | [139] “Manual of Geology,” p. 677. | | | | [140] Quart. Journ. Geol. Soc., vol. ix., p. 306. | | | | [141] Dana’s “Manual of Geology,” p. 677. | | | | [142] Quart. Journ. Geol. Soc., vol. ix., p. 306. | | | | [143] “Journal,” vol. i., p. 38. | | | | [144] “Short American Tramp,” pp. 168, 174. | | | | [145] “Short American Tramp,” pp. 239−241. | | | | [146] “Travels in North America,” vol. ii., p. 137. | | | | [147] Ibid., vol. ii., p. 174. | | | | [148] Proceedings of the Royal Society of Edinburgh, Session | | 1865−66, p. 537. | | | | [149] “Short American Tramp,” pp. 77, 81, 111. | | | | [150] “Second Visit,” vol. ii., p. 367. | | | | [151] “Memoirs of Boston Society of Natural History,” vol. i. | | (1867), p. 228. | | | | [152] “Antiquity of Man,” p. 268. Third Edition. | | | | [153] “Great Ice Age,” p. 512. | | | | [154] Brit. Assoc., 1870, p. 88. | | | | [155] Quart. Journ. Geol. Soc., vol. v., p. 10. Phil. Mag. for | | April, 1865, p. 289. | | | | [156] “Great Ice Age,” p. 512. | | | | [157] Jukes’ “Manual of Geology,” p. 421. | | | | [158] See also Quarterly Journal Geological Society, vol. xi., p. | | 510. | | | | [159] The _Reader_ for August 12, 1865. | | | | [160] “History of the Isle of Man,” p. 86. My colleague, Mr. John | | Horne, in his “Sketch of the Geology of the Isle of Man,” Trans. of | | Edin. Geol. Soc., vol. ii., part iii., considers this conglomerate | | to be of Lower Carboniferous age. | | | | [161] See Selwyn, “Phys. Geography and Geology of Victoria.” 1866. | | pp. 15−16; Taylor and Etheridge, _Geol. Survey Vict., Quarter Sheet | | 13, N.E._ | | | | [162] Report on the Geology of the District of Ballan, Victoria. | | 1866. p. 11. | | | | [163] _Atrypa reticularis._ | | | | [164] Quart. Journ. Geol. Soc., vol. xii., p. 58. | | | | [165] “Great Ice Age,” p. 513. | | | | [166] “Great Ice Age,” p. 513. | | | | [167] Brit. Assoc. Report for 1873. | | | | [168] Quart. Journ. Geol. Soc., vol. xi., p. 519. | | | | [169] _Orthis resupinata._ | | | | [170] _Prod. semireticulatus_ var. _Martini_. Sow. | | | | [171] “Belcher’s Voyage,” vol. ii., p. 377. | | | | [172] “Journal of a Boat Voyage through Rupert-Land,” vol. ii., p. | | 208. | | | | [173] Quart. Journ. Geol. Soc., vol. xi., p. 197. | | | | [174] Explanation Memoir to Sheet 47, “Geological Survey of | | Ireland.” | | | | [175] Phil. Mag., vol. xxix., p. 290. | | | | [176] “Memoirs of the Geological Survey of India,” vol. i., part i. | | | | [177] Quart. Journ. Geol. Soc., vol. xxvi., p. 514. | | | | [178] Ibid., vol. xxvii., p. 544. | | | | [179] Phil. Mag., vol. xxix., p. 290. | | | | [180] Journal of the Royal Dublin Society for February, 1857. | | | | [181] Quart. Journ. Geol. Soc., vol. xi., p. 519. | | | | [182] “The Last of the Arctic Voyages,” by Captain Sir E. Belcher, | | vol. ii., p. 389. Appendix Brit. Assoc. Report for 1855, p. 79. | | | | [183] Ibid., vol. ii., p. 379. Appendix. | | | | [184] “Manual of Geology,” pp. 395, 493. | | | | [185] Appendix to McClintock’s “Arctic Discoveries.” | | | | [186] Quart. Journ. Geol. Soc., vol. xiv., p. 262. Brit. Assoc. | | Report for 1857, p. 62. | | | | [187] Quart. Journ. Geol. Soc., vol. xvi., p. 327. _Geologist_, | | 1860, p. 38. | | | | [188] Phil. Mag., vol. xxix., p. 290. | | | | [189] Trans. Geol. Soc. of Glasgow, vol. v., p. 64. | | | | [190] “Principles,” vol. i., p. 209. Eleventh Edition. | | | | [191] “Memoirs of the Royal Academy of Science of Turin,” Second | | Series, vol. xx. I am indebted for the above particulars to | | Professor Ramsay, who visited the spot along with M. Gastaldi. | | | | [192] “Antiquity of Man,” Second Edition, p. 237. | | | | [193] Dr. Robert Brown, in a recent Memoir on the Miocene Beds of | | the Disco District (Trans. Geol. Soc. Glasg., vol. v., p. 55), | | has added considerably to our knowledge of these deposits. He | | describes the strata in detail, and gives lists of the plant and | | animal remains discovered by himself and others, and described by | | Professor Heer. Professor Nordenskjöld has likewise increased the | | data at our command (Transactions of the Swedish Academy, 1873); | | and still further evidence in favour of a warm climate having | | prevailed in Greenland during Miocene times has been obtained by | | the recent second German polar expedition. | | | | [194] The following are M. Leverrier’s formulæ for computing the | | eccentricity of the earth’s orbit, given in his “Memoir” in the | | _Connaissance des Temps_ for 1843:— | | | | Eccentricity in (_t_) years after January 1, 1800 | | _____________ | | = √_h_^2 + _l_^2 where | | | | _h_ = 0·000526 Sin (_gt_ + _ß_) + 0·016611 Sin (_g_{1}t_ + _ß_{1}_) | | + 0·002366 Sin (_g_{2}t_ + _ß_{2}_) | | + 0·010622 Sin (_g_{3}t_ + _ß_{3}_) | | - 0·018925 Sin (_g_{4}t_ + _ß_{4}_) | | + 0·011782 Sin (_g_{5}t_ + _ß_{5}_) | | - 0·016913 Sin (_g_{6}t_ + _ß_{6}_) | | and | | | | _l_ = 0·000526 Cos (_gt_ + _ß_) + 0·016611 Cos (_g_{1}t_ + _ß_{1}_) | | + 0·002366 Cos (_g_{2}t_ + _ß_{2}_) | | + 0·010622 Cos (_g_{3}t_ + _ß_{3}_) | | - 0·018925 Cos (_g_{4}t_ + _ß_{4}_) | | + 0·011782 Cos (_g_{5}t_ + _ß_{5}_) | | - 0·016913 Cos (_g_{6}t_ + _ß_{6}_) | | | | _g_ = 2″·25842 _ß_ = 126° 43′ 15″ | | _g_{1}_ = 3″·71364 _ß_{1}_ = 27 21 26 | | _g_{2}_ = 22″·4273 _ß_{2}_ = 126 44 8 | | _g_{3}_ = 5″·2989 _ß_{3}_ = 85 47 45 | | _g_{4}_ = 7″·5747 _ß_{4}_ = 35 38 43 | | _g_{5}_ = 17″·1527 _ß_{5}_ = −25 11 33 | | _g_{6}_ = 17″·8633 _ß_{6}_ = −45 28 59 | | | | [195] See Professor C. V. Zenger’s paper “On the Periodic Change cf | | Climate caused by the Moon,” Phil. Mag. for June, 1868. | | | | [196] Phil. Mag. for February, 1867. | | | | [197] Phil. Mag. for May, 1868. | | | | [198] Student’s “Elements of Geology,” p. 91. Second Edition. | | | | [199] In an interesting memoir, published in the Phil. Mag. for | | 1850, Mr. Alfred Tylor estimated that the basin of the Mississippi | | is being lowered at the rate of one foot in 10,000 years by the | | removal of the sediment; and he proceeds further, and reasons that | | one foot removed off the general surface of the land during that | | period would raise the sea-level three inches. Had it not been that | | Mr. Tylor’s attention was directed to the effects produced by the | | removal of sediment in raising the level of the ocean rather than | | in lowering the level of the land, he could not have failed to | | perceive that he was in possession of a key to unfold the mystery | | of geological time. | | | | [200] Proc. Roy. Soc., No. 152, 1874. | | | | [201] I have taken for the volume and mass of the sun the values | | given in Professor Sir William Thomson’s memoir, Phil. Mag., vol. | | viii. (1854). | | | | [202] Phil. Mag., § 4, vol. xi., p. 516 (1856). | | | | [203] Phil. Mag. for July, 1872, p. 1. | | | | [204] “Principles,” p. 210. Eleventh Edition. | | | | [205] “Principles,” vol. i., p. 107. Tenth Edition. | | | | [206] The conception of submergence resulting from displacement of | | the earth’s centre of gravity, caused by a heaping up of ice at | | one of the poles, was first advanced by M. Adhémar, in his work | | “_Révolutions de la Mer_,” 1842. When the views stated in this | | chapter appeared in the _Reader_, I was not aware that M. Adhémar | | had written on the subject. An account of his mode of viewing the | | question is given in the Appendix. | | | | [207] Petermann’s _Geog. Mittheilungen_, 1871, Heft. x., p. 377. | | | | [208] Geol. Mag., 1872, vol. ix., p. 360. | | | | [209] “Open Polar Sea,” p. 134. | | | | [210] Journal of the Royal Geographical Society, 1853, vol. xxiii. | | | | [211] “Physics of Arctic Ice,” Quart. Journ. Geol. Soc. for | | February, 1871. | | | | [212] Some writers have objected to the conclusion that the | | antarctic ice-cap is thickest at the pole, on the ground that the | | snowfall there is probably less than at lower latitudes. The fact | | is, however, overlooked, that the greater thickness of an ice-cap | | at its centre is a physical necessity not depending on the rate of | | snowfall. Supposing the snowfall to be greater at, say, lat. 70° | | than at 80°, and greater at 80° than at the pole; nevertheless, the | | ice will continue to accumulate till it is thicker at 80° than at | | 70°, and at the pole than it is at 80°. | | | | [213] It is a pity that at present no record is kept, either by | | the Board of Trade or by the Admiralty, of remarkable icebergs | | which may from time to time be met with. Such a record might be of | | little importance to navigation, but it would certainly be of great | | service to science. | | | | [214] See Chapter XXVII., and also Geol. Mag. for May and June, | | 1870, and January, 1871. | | | | [215] Phil. Mag. for April, 1866, p. 323. | | | | [216] Ibid., for March, 1866, p. 172. | | | | [217] _Reader_, February 10, 1866. | | | | [218] In a former paper I considered the effects of another cause, | | viz., the melting of polar ice resulting from an increase of the | | Obliquity of the Earth’s Orbit.—Trans. Glasgow Geol. Soc., vol. | | ii., p. 177. Phil. Mag., June, 1867. See also Chapter XXV. | | | | [219] Phil. Mag. for November, 1868, p. 376. | | | | [220] Phil. Mag., November, 1868. | | | | [221] “Origin of Species,” chap. xi. Fifth Edition. | | | | [222] Lieutenant-Colonel Drayson (“Last Glacial Epoch of Geology”) | | and also Mr. Belt (Quart. Journ. of Science, October, 1874) state | | that Leverrier has lately investigated the question as to the | | extent of the variation of the plane of the ecliptic, and has | | arrived at results differing considerably from those of Laplace; | | viz., that the variation may amount to 4° 52′, whereas, according | | to Laplace, it amounts to only 1° 21′. I fear they are comparing | | things that are totally different; viz., the variation of the | | plane of the ecliptic in relation to its mean position with its | | variation in relation to the equator. Laplace estimated that the | | plane of the ecliptic would oscillate to the extent of 4° 53′ 33″ | | on each side of its mean position, a result almost identical with | | that of Leverrier, who makes it 4° 51′ 42″. But neither of these | | geometricians ever imagined that the ecliptic could change in | | relation to the equator to even one-third of that amount. | | | | Laplace demonstrated that the change in the plane of the ecliptic | | affected the position of the equator, causing it to vary along with | | it, so that the equator could never possibly recede further than | | 1° 22′ 34″ from its mean position in relation to the ecliptic | | (“_Mécanique Céleste_,” vol. ii., p. 856, Bowditch’s Translation; | | see also Laplace’s memoir, “Sur les Variations de l’Obliquité de | | l’Écliptique,” _Connaissance des Temps_ for 1827, p. 234), and I am | | not aware that Leverrier has arrived at a different conclusion. | | | | [223] Memoir on the Secular Variations of the Elements of the | | Orbits of the Planets, “Smithsonian Contributions to Knowledge,” | | vol. xvii. | | | | [224] “Smithsonian Contributions to Knowledge,” vol. ix. | | | | [225] “Distribution of Heat on the Surface of the Globe,” p. 14. | | | | [226] Chapter IV. | | | | [227] Quart. Journ. Geol. Soc., June, 1866, p. 564. | | | | [228] Quart. Journ. Geol. Soc., vol. xxi., p. 186. | | | | [229] “Geological Observer,” p. 446. See also Mr. James Geikie’s | | valuable Memoir, “On the Buried Forests and Peat Mosses of | | Scotland.” Trans. of the Royal Society of Edinburgh, vol. xxiv., | | and Chambers’ “Ancient Sea-Margins.” | | | | [230] See Lyell’s “Antiquity of Man,” Second Edition, p. 282; | | “Elements,” Sixth Edition, p. 162. | | | | [231] In order to determine the position of the solstice-point | | in relation to the aphelion, it will not do to assume, as is | | commonly done, that the point makes a revolution from aphelion to | | aphelion in any regular given period, such as 21,000 years; for | | it is perfectly evident that owing to the great irregularity in | | the motion of the aphelion, no two revolutions will probably be | | performed in the same length of period. For example, the winter | | solstice was in the aphelion about the following dates: 11,700, | | 33,300, and 61,300 years ago. Here are two consecutive revolutions, | | the one performed in 21,600 years and the other in 28,000 years; | | the difference in the length of the two periods amounting to no | | fewer than 6,400 years. | | | | [232] Quart. Journ. Geol. Soc., vol. xxvii., p. 232. See also “The | | Last Glacial Epoch of Geology,” by the same author. | | | | [233] Quart. Journ. of Science, October, 1874. | | | | [234] The longer diameter passes from long. 14° 23′ E. to long. | | 165° 37′ W. | | | | [235] “Principles,” vol. i., p. 294. Eleventh Edition. | | | | [236] Phil. Mag. for August, 1864. | | | | [237] “Elementary Geology,” p. 399. | | | | [238] “The Past and Present Life of the Globe,” p. 102. | | | | [239] “Memoirs of the Geological Survey,” vol. ii., Part 2, p. 404. | | | | [240] “Coal Fields of Great Britain,” p. 45. Third Edition. | | | | [241] “Journal of Researches,” chap. xiii. | | | | [242] “Coal Fields of Great Britain,” p. 67. | | | | [243] See “Smithsonian Report for 1857,” p. 138. | | | | [244] Quart. Journ. Geol. Soc., May, 1865, p. civ. | | | | [245] “Geology of Fife and the Lothians,” p. 116. | | | | [246] “Life on the Earth,” p. 133. | | | | [247] Quart. Journ. Geol. Soc., vol. xi., p. 535. | | | | [248] Ibid., vol. xii., p. 39. | | | | [249] Miller’s “Sketch Book of Practical Geology,” p. 192. | | | | [250] From Geological Magazine, May and June, 1870; with a few | | verbal corrections, and a slight re-arrangement of the paragraphs. | | | | [251] See Phil. Mag. for November, 1868, p. 374. | | | | [252] See Phil. Mag. for November, 1868, pp. 366−374. | | | | [253] Journ. Geol. Soc., vol. xxi., p. 165. | | | | [254] Specimens of the striated summit and boulder clay stones are | | to be seen in the Edinburgh Museum of Science and Art. | | | | [255] Phil. Mag. for April, 1866. | | | | [256] “Tracings of the North of Europe,” 1850, pp. 48−51. | | | | [257] Quart. Journ. Geol. Soc., vol. ii., p. 364. | | | | [258] “Tracings of the North of Europe,” by Robert Chambers, pp. | | 259, 285. “Observations sur les Phénomènes d’Erosion en Norvège,” | | by M. Hörbye, 1857. See also Professor Erdmann’s “Formations | | Quaternaires de la Suède.” | | | | [259] “Glacial Drift of Scotland,” p. 29. | | | | [260] Geological Magazine, vol. ii., p. 343. Brit. Assoc. Rep., | | 1864 (sections), p. 59. | | | | [261] Trans. Roy. Soc. Edin., vol. vii., p. 265. | | | | [262] “Tracings of Iceland and the Faroe Islands,” p. 49. | | | | [263] See Chap. XXIII. | | | | [264] Mr. Thomas Belt has subsequently advanced (Quart. Jour. Geol. | | Soc., vol. xxx., p. 490), a similar explanation of the steppes of | | Siberia. He supposes that an overflow of ice from the polar basin | | dammed back all the rivers flowing northward, and formed an immense | | lake which extended over the lowlands of Siberia, and deposited the | | great beds of sand and silt with occasional freshwater shells and | | elephant remains, of which the steppes consist. | | | | [265] Proc. Roy. Phys. Soc., Edin., vols. ii. and iii. | | | | [266] From Geol. Mag. for January, 1871. | | | | [267] Quart. Journ. Geol. Soc., xxvi., p. 517. | | | | [268] British Assoc. Report for 1864 (sections), p. 65. | | | | [269] Quart. Journ. Geol. Soc., xxvi., p. 90. | | | | [270] Geol. Mag., vii., p. 349. | | | | [271] Trans. Edin. Geol. Soc., vol. i., p. 136. | | | | [272] Geol. Mag. for June, 1870. See Chap. XXVII. | | | | [273] This was done by Mr. R. H. Tiddeman of the Geological Survey | | of England (Quart. Journ. Geol. Soc. for November, 1872), and the | | result established the correctness of the above opinion as to the | | existence of a North of England ice-sheet. Additional confirmation | | has been derived from the important observations of Mr. D. | | Mackintosh, and also of Mr. Goodchild, of the Geological Survey of | | England. | | | | [274] Trans. Geol. Soc., vol. v., p. 516 (first series). | | | | [275] Quart. Journ. Geol. Soc., vol. xi., p. 492. “Memoir of the | | Country around Cheltenham,” 1857. “Geology of the Country around | | Woodstock,” 1859. | | | | [276] Geol. Mag., vol. vii., p. 497. | | | | [277] Quart. Journ. Geol. Soc., vol. xxvi., p. 90. | | | | [278] My colleague, Mr. R. L. Jack. | | | | [279] The greater portion of this chapter is from the Trans. of | | Geol. Soc. of Edinburgh, for 1869. | | | | [280] Chapter XV., p. 253. | | | | [281] Trans. of the Geol. Soc. of Glasgow, vol. iii., part i., page | | 133. | | | | [282] Mr. Milne Home has advanced, in his “Estuary of the Firth of | | Forth,” p. 91, the theory that this trough had been scooped out | | during the glacial epoch by icebergs floating through the Midland | | valley from west to east when it was submerged. The bottom of the | | trough, be it observed, at the watershed at Kilsyth, is 300 feet | | above the level of its bottom at Grangemouth; and this Mr. Milne | | Home freely admits. But he has not explained how an iceberg, which | | could float across the shallow water at Kilsyth, say, 100 feet | | deep, could manage to grind the rocky bottom at Grangemouth, where | | it was not less than 400 feet deep. “The impetus acquired in the | | Kyle at Kilsyth,” says Mr. Milne Home, “would keep them moving on, | | and the prevailing westerly winds would also aid, so that when | | _grating_ on the subjacent carboniferous rocks they would not have | | much difficulty in scooping out a channel both wider and deeper | | than at Kilsyth.” But how could they “_grate_ on the subjacent | | carboniferous rocks” at Grangemouth, if they managed to _float_ | | at Kilsyth? Surely an iceberg that could “_grate_” at Grangemouth | | would “_ground_” at Kilsyth. | | | | [283] Trans. of the Geol. Soc. of Glasgow, vol. iii., p. 141. | | | | [284] Mr. John Young and Mr. Milne Home advanced the objection, | | that several trap dykes cross the valley of the Clyde near Bowling, | | and come to so near the present surface of the land, that the | | Clyde at present flows across them with a depth not exceeding | | 20 feet. I fear that Mr. Young and Mr. Milne Home have been | | misinformed in regard to the existence of these dykes. About a mile | | _above_ Bowling there are one or two dykes which approach to the | | river-bank, and may probably cross, but these could not possibly | | cut off a channel entering the Clyde at Bowling. In none of the | | borings or excavations which have been made by the Clyde Trustees | | has the rock been reached from Bowling downwards. I may also state | | that the whole Midland valley, from the Forth of Clyde to the Firth | | of Forth, has been surveyed by the officers of the Geological | | Survey, and only a single dyke has been found to cross the buried | | channels, viz., one (Basalt rock) running eastward from Kilsyth to | | the canal bridge near Dullatur. But as this is not far from the | | watershed between the two channels it cannot affect the question at | | issue. See sheet 31 of Geological Survey Map of Scotland. | | | | [285] Trans. Geol. Soc. Glasgow, vol. iv., p. 166. | | | | [286] “Great Ice Age,” chap. xiii. | | | | [287] See further particulars in Mr. Bennie’s paper on the Surface | | Geology of the district around Glasgow, Trans. Geol. Soc. of | | Glasgow, vol. iii. | | | | [288] See also Smith’s “Newer Pliocene Geology,” p. 139. | | | | [289] British Association Report for 1863, p. 89. _Geologist_ for | | 1863, p. 384. | | | | [290] See Geological Magazine, vol. ii., p. 38. | | | | [291] Proc. Geol. Soc., vol. iii., 1840, p. 342. | | | | [292] “Antiquity of Man” (Third Edition), p. 249. | | | | [293] “Glacial Drift of Scotland,” p. 65. Trans. Geol. Soc. Glas., | | vol. i., part 2. | | | | [294] “Memoir, Geological Survey of Scotland,” Sheet 23, p. 42. | | | | [295] Mr. Robert Dick had previously described, in the Trans. Geol. | | Soc. Edinburgh, vol. i., p. 345, portions of these buried channels. | | He seems, however, to have thought that they formed part of one and | | the same channel. | | | | [296] A description of this channel was read to the Natural History | | Society of Glasgow by Mr. James Coutts, the particulars of which | | will appear in the Transactions of the Society. | | | | [297] “Occasional Papers,” pp. 166, 223. | | | | [298] Memoir read before the Royal Society, January 7, 1869. | | | | [299] “Alpine Journal,” February, 1870. | | | | [300] Phil. Mag., January, 1872. | | | | [301] Phil. Mag., July, 1870; February, 1871. | | | | [302] Philosophical Magazine for January, 1870, p. 8; Proceedings | | of the Royal Society for January, 1869. | | | | [303] Philosophical Magazine for March, 1869. | | | | [304] Proceedings of Bristol Naturalists’ Society, p. 37 (1869). | | | | [305] Ibid., vol. iv., p. 37 (new series). | | | | [306] Phil. Mag., S. 4, vol. x., p. 303. | | | | [307] Proceedings of the Bristol Naturalists’ Society, vol. iv., p. | | 39 (new series). | | | | [308] See Philosophical Transactions, December, 1857. | | | | [309] There is one circumstance tending slightly to prevent the | | rupture of the glacier, when under tension, which I do not remember | | to have seen noticed; that is, the cooling effect which is produced | | in solids, such as ice, when subjected to tension. Tension would | | tend to lower the temperature of the ice-molecules, and this | | lowering of temperature would have the tendency of freezing them | | more firmly together. The cause of this cooling effect will be | | explained in the Appendix. | | | | [310] Phil. Mag., March, 1869; September, 1870. | | | | [311] “Forms of Water,” p. 127. | | | | [312] See text, p. 10. | | | | [313] Mathematical and Physical Series, vol. xxxvi. (1765). | | | | [314] “Memoirs of St. Petersburg Academy,” 1761. | | | | [315] The calculations here referred to were made by Lagrange | | nearly half a century previous to the appearance of this paper, and | | published in the “Mémoires de l’Académie de Berlin,” for 1782, p. | | 273. Lagrange’s results differ but slightly from those afterwards | | obtained by Leverrier, as will be seen from the following table; | | but as he had assigned erroneous values to the masses of the | | smaller planets, particularly that of Venus, the mass of which he | | estimated at one-half more than its true value, full confidence | | could not be placed in his results. | | | | Superior limits of eccentricity as determined by Lagrange, | | Leverrier, and Mr. Stockwell:— | | | | By Lagrange. By Leverrier. By Mr. Stockwell. | | | | Mercury 0·22208 0·225646 0·2317185 | | Venus 0·08271 0·086716 0·0706329 | | Earth 0·07641 0·077747 0·0693888 | | Mars 0·14726 0·142243 0·139655 | | Jupiter 0·06036 0·061548 0·0608274 | | Saturn 0·08408 0·084919 0·0843289 | | Uranus — 0·064666 0·0779652 | | Neptune — — 0·0145066 | | | | [J. C.] | | | | [316] “Mém. de l’Acad. royale des Sciences.” 1827. Tom. vii., p. | | 598. | | | | [317] Absolute zero is now considered to be only 493° Fah. below | | the freezing-point, and Herschel himself has lately determined | | 271° below the freezing-point to be the temperature of space. | | Consequently, a decrease, or an increase of one per cent. in the | | mean annual amount of radiation would not produce anything like the | | effect which is here supposed. But the mean annual amount of heat | | received cannot vary much more than one-tenth part of one per cent. | | In short, the effect of eccentricity on the mean annual supply of | | heat received from the sun, in so far as geological climate is | | concerned, may be practically disregarded.—[J. C.] | | | | [318] “Principles of Geology,” p. 110. “Mr. Lyell, however, in | | stating the actual excess of eight days in the duration of the | | sun’s presence in the northern hemisphere over that in the southern | | as productive of an excess of light and heat annually received by | | the one over the other hemisphere, appears to have misconceived the | | effect of elliptic motion in the passage here cited, since it is | | demonstrable that whatever be the ellipticity of the earth’s orbit | | the two hemispheres must receive equal absolute quantities of light | | and heat per annum, the proximity of the sun in perigee exactly | | compensating the effect of its swifter motion. This follows from a | | very simple theorem, which may be thus stated: ‘The amount of heat | | received by the earth from the sun while describing any part of | | its orbit is proportional to the angle described round the sun’s | | centre,’ so that if the orbit be divided into two portions by a | | line drawn _in any direction_ through the sun’s centre, the heats | | received in describing the two unequal segments of the ellipse so | | produced will be equal.” | | | | [319] When the eccentricity of the earth’s orbit is at its superior | | limit, the absolute quantity of heat received by the globe during | | one year will be increased by only 1/300th part; an amount which | | could produce no sensible influence on climate.—[J. C.] | | | | [320] Sir Charles has recently, to a certain extent, adopted the | | views advocated in the present volume, viz., that the cold of the | | glacial epoch was brought about not by a _decrease_, but by an | | _increase_ of eccentricity. (See vol. i. of “Principles,” tenth | | and eleventh editions.) The decrease in the mean annual quantity | | of heat received from the sun, resulting from the decrease in | | the eccentricity of the earth’s orbit—the astronomical cause to | | which he here refers—could have produced no sensible effect on | | climate.—[J. C.] | | | | [321] It is singular that both Arago and Humboldt should appear to | | have been unaware of the researches of Lagrange on this subject. | | | | [322] “Révolutions de la Mer,” p. 37. Second Edition. | | | | [323] See text, p. 37. | | | | [324] See _Philosophical Magazine_ for December, 1867, p. 457. | | | | [325] _Silliman’s American Journal_ for July, 1864. _Philosophical | | Magazine_ for September, 1864, pp. 193, 196. | | | | [326] _Philosophical Magazine_ for August, 1865, p. 95. | | | | [327] See text, p. 80. | | | | [328] See text, p. 222. | | | | [329] Proc. Roy. Soc., No. 157, 1875. | | | | [330] See text, p. 522. | | | | [331] Phil. Trans. for 1859, p. 91. | | | | [332] See text, p. 527. | | | +----------------------------------------------------------------------+

Transcriber’s Notes:

- Text enclosed by underscores is in italics (_italics_). - Blank pages have been removed. - Obvious typographical errors have been silently corrected. - Some spelling and hyphenation variations have been made consistent.