1. Philosophical Magazine, May 1868; Climate and Time, chap. xxi.; Quarterly Journal of Science, July 1877; Phil. Mag., July 1878; Climate and Cosmology, chaps. xvii. xviii. and xix.
2. I prefer to use the term “theory,” with the above understood qualification, viz. a theory in its hypothetical stage.
3. Pouillet’s estimate of the rate of solar radiation is here taken.
4. Lecture on “The Probable Origin, the Total Amount, and the Possible Duration of the Sun’s Heat,” delivered at the Royal Institution on January 21, 1887, and published in Nature of 27th of the same month. The lecture was afterwards published with considerable additions and alterations in the Proceedings of the Institution vol. xii. It is from this that my quotations are taken.
5. Proceedings of the Royal Institution, vol. xii. p. 15.
6. Manchester Science Lectures, Fifth Series, p. 31.
7. Newcomb’s Astronomy, p. 487, English edition, 1878.
8. World Life. p. 27.
9. Philosophical Magazine, July 1878; Climate and Cosmology, Chap. xix.
10. Proceedings of Royal Society, vol. xliii. p. 117.
11. Good Words for 1875, p. 861.
12. Manchester Science Lectures.
13. Proc. of Royal Society, vol. xliv. p. 5.
14. World Life, or Comparative Geology, by Alexander Winchell, LL.D., Professor of Geology and Palæontology in the University of Michigan. Chicago: S. C. Griggs & Co. 1883.
15. Other Worlds, chap. ix.
16. Manchester Science Lectures.
17. Proceedings of Royal Institution, vol. xii. p. 16.
18. Laplace held a more accurate view of the primitive condition of the solar nebula. He considered that, owing to intense heat, the solar mass became expanded to the limits of the remotest planetary orbit of our system; that, in cooling, it began slowly to condense; and that, as condensation went on, planet after planet became detached from the mass. Laplace, however, offered no explanation of the manner in which the primitive nebula obtained its heat.
19. Proceedings of Royal Institution, vol. xii. p. 15.
20. Proceedings of the Royal Society, vol. xliii. p. 140.
21. Philosophical Transactions for 1811.
22. Recent Advances in Physical Sciences, p. 175.
23. Proceedings of the American Association for the Advancement of Science for 1848.
24. Philosophical Magazine, February 1867. I was not aware at this time that Mr. Alfred Tylor had previously applied the same method to determine an entirely different point, viz.: how much the sea-level is being raised by the sediment deposited on the sea-bottom. Mr. Tylor’s paper, entitled “On Changes of the Sea-Level effected by existing Physical Causes during stated Periods of Time,” appeared in the Phil. Mag. for April 1853. Mr. Tylor came to the conclusion that the sea-level was being raised, from this cause, about 3 inches in 10,000 years.
25. Report upon the Physics and Hydraulics of the Mississippi.
26. Trans. of Geol. Soc. of Glasgow, vol. iii.; Jukes & Geikie’s Manual of Geology, chap. xxv.; Text Book of Geology, p. 441.
27. Student’s Elements of Geology, p. 91.
28. World Life, p. 265.
29. See Climate and Time, p. 337.
30. Physical Geography, p. 103.
31. It is this destruction of the stratified rocks which makes it so difficult to detect the marks of former glacial epochs, and which has led to such prevailing misconceptions regarding the evidence which we ought to expect of those epochs. See paper read before the Geological Society, “On Prevailing Misconceptions regarding the Evidence which we ought to expect of former Glacial Periods,” January 23, 1889.
32. Physical Geography, p. 94.
33. Quart. Journ. of Science, July 1877; Climate and Cosmology, chap. xvii.
34. Mem. Geol. Survey of Lancashire, 1862.
35. Mem. Geol. Survey of Great Britain, vol. iii.
36. Memoir to Sheet 32, Geol. Survey Map of Scotland.
37. Nature, vol. xiii. p. 390.
38. Explanation to Sheet 15, Geol. Survey Map of Scotland.
39. I have been informed by Mr. Peach that since the above was written additional light has been cast on this immense fault. It has been found, he says, that the fault consists of two sub-parallel branches, the more southerly of which has the effect of bringing the rocks of the Upper Silurian age against the Lower Silurian beds. The northern branch brings the upper division of the Lower Old Red Sandstones, in turn, against the Upper Silurian rocks. This, Mr. Peach remarks, does not in the least invalidate the reasoning as to the amount of material removed by denudation from this region in the time specified. In fact, it shows, he says, that a greater amount must have been removed than was at first suspected.
40. Jukes’s and Geikie’s Manual of Geology, p. 441.
41. Geology of Canada, 1863, p. 61.
42. Safford’s Geology of Tennessee, p. 309.
43. Lyell’s Student’s Manual, chap. xxiii.
44. Geological Studies, by Prof. A. Winchell, p. 165.
45. Geological Studies, pp. 93, 163.
46. Powell’s Geology of the Uinta Mountains.
47. Geological Exploration of the Fortieth Parallel, vol. ii. p. 456.
48. Geological Studies, p. 92; see also Dutton’s Tertiary History of the Cañon District.
49. Tertiary History of the Cañon District, pp. 20, 113; Second Annual Report, U.S. Geol. Survey, p. 125.
50. Powell’s Geology of Uinta Mountains.
51. Geological Exploration of the Fortieth Parallel, vol. i. p. 745.
52. Memoir to Sheet 32, Geol. Survey of Scotland.
53. Denudation of South Wales. Memoirs of Geol. Survey, vol. i.
54. Quart. Journ. Geol. Soc. vol. xxiv. p. 323.
55. World Life, p. 369.
56. Island Life, p. 204.
57. Quart. Journ. of Geol. Soc. vol. xxvi. p. 53.
58. Origin of Species, p. 286.
59. Proceedings of the Royal Society, No. 152, 1874, p. 342.
60. Island Life, p. 205.
61. Of course, Mr. Wallace does not believe that it is actually 200,000,000 years since the Cambrian period.
62. World Life, p. 196.
63. World Life, p. 72.
64. Correlation of Physical Forces, p. 164 (fifth edition), 1867.
65. Popular Science Monthly for January 1873.
66. See also on this point Mr. Lockyer’s “Bakerian Lecture,” Proc. Roy. Soc. No. 266, p. 21.
67. Proc. Roy. Soc. vol. xxviii. p. 160.
68. Proc. Roy. Soc. vol. xxxii. p. 230.
69. Ideal Chemistry, p. 56.
70. American Journal of Science, vol. xxiii. p. 124.
71. “Our atmosphere,” says Dr. Hunt, “is not terrestrial, but cosmical, being a universal medium diffused throughout all space, but condensed around the various centres of attraction in amount proportional to their mass and temperature, the waters of the ocean themselves belonging to this universal atmosphere.” (Nature, August 29, 1878, p. 475.) Similar views have been advocated by Mr. Mattieu Williams, who says “that the gaseous ocean, in which we are immersed, is but a portion of the infinite atmosphere that fills the whole solidity of space; that links together all the elements of the universe, and diffuses among them their heat and light, and all the other physical and vital forces which heat and light are capable of generating.” (Fuel of the Sun, p. 5.) In 1854 Sir William Thomson suggested the idea that the luminiferous ether was probably a continuation of our atmosphere, though I do not think he continues to hold that opinion. The first to advance this idea was, undoubtedly, Newton, who assumed interplanetary space to be universally filled with an ethereal medium “much of the same constitution as air, but far rarer, subtler, and more elastic.”
72. World Life, p. 533.
73. Nature, February 1, 1883, p. 330.
74. Protyle is the term adopted by Mr. Crookes to designate the original primal matter existing before the evolution of the chemical elements, and out of which they were evolved. Protyle in chemistry is analogous to protoplasm in biology, with this difference, however, that protyle is as yet hypothetical, whereas protoplasm is known to be real.
75. Popular Science Monthly for February 1876. See also the January number for 1873.
76. Proc. Roy. Soc. for April 19, 1888, p. 115.
77. The dark stellar masses which escape observation may be as numerous as those that are visible.