A temperature (or absence of temperature) closely approximating this is believed to obtain in the ethereal ocean of interplanetary and interstellar space, which transmits, but is thought not to absorb, radiant energy. We here on the earth's surface are protected from exposure to this cold, which would deprive every organic thing of life almost instantaneously, solely by the thin blanket of atmosphere with which the globe is coated. It would seem as if this atmosphere, exposed to such a temperature at its surface, must there be incessantly liquefied, and thus fall back like rain to be dissolved into gas again while it still is many miles above the earth's surface. This may be the reason why its scurrying molecules have not long ago wandered off into space and left the world without protection.
But whether or not such liquefaction of the air now occurs in our outer atmosphere, there can be no question as to what must occur in its entire depth were we permanently shut off from the heating influence of the sun, as the astronomers threaten that we may be in a future age. Each molecule, not alone of the atmosphere, but of the entire earth's substance, is kept aquiver by the energy which it receives, or has received, directly or indirectly, from the sun. Left to itself, each molecule would wear out its energy and fritter it off into the space about it, ultimately running completely down, as surely as any human-made machine whose power is not from time to time restored. If, then, it shall come to pass in some future age that the sun's rays fail us, the temperature of the globe must gradually sink towards the absolute zero. That is to say, the molecules of gas which now fly about at such inconceivable speed must drop helpless to the earth; liquids must in turn become solids; and solids themselves, their molecular quivers utterly stilled, may perhaps take on properties the nature of which we cannot surmise.
Yet even then, according to the current hypothesis, the heatless molecule will still be a thing instinct with life. Its vortex whirl will still go on, uninfluenced by the dying-out of those subordinate quivers that produced the transitory effect which we call temperature. For those transitory thrills, though determining the physical state of matter as measured by our crude organs of sense, were no more than non-essential incidents; but the vortex whirl is the essence of matter itself. Some estimates as to the exact character of this intramolecular motion, together with recent theories as to the actual structure of the molecule, will claim our attention in a later volume. We shall also have occasion in another connection to make fuller inquiry as to the phenomena of low temperature.
APPENDIX
REFERENCE-LIST
CHAPTER I
THE SUCCESSORS OF NEWTON IN ASTRONOMY (1) (p. 10). An Account of Several
Extraordinary Meteors or Lights in the Sky, by Dr. Edmund Halley. Phil.
Trans. of Royal Society of London, vol. XXIX, pp. 159-162. Read before
the Royal Society in the autumn of 1714. (2) (p. 13). Phil. Trans. of
Royal Society of London for 1748, vol. XLV., pp. 8, 9. From A Letter to
the Right Honorable George, Earl of Macclesfield, concerning an Apparent
Motion observed in some of the Fixed Stars, by James Bradley, D.D.,
Astronomer Royal and F.R.S.
CHAPTER II
THE PROGRESS OF MODERN ASTRONOMY
(1) (p. 25). William Herschel, Phil. Trans. for 1783, vol. LXXIII. (2)
(p. 30). Kant's Cosmogony, ed. and trans. by W. Hartie, D.D., Glasgow,
900, pp. 74-81. (3) (p. 39). Exposition du systeme du monde (included in
oeuvres Completes), by M. le Marquis de Laplace, vol. VI., p. 498. (4)
(p. 48). From The Scientific Papers of J. Clerk-Maxwell, edited by W.
D. Nevin, M.A. (2 vols.), vol. I., pp. 372-374. This is a reprint of
Clerk-Maxwell's prize paper of 1859.
CHAPTER III
THE NEW SCIENCE OF PALEONTOLOGY
(1) (p. 81). Baron de Cuvier, Theory of the Earth, New York, 1818, p.
98. (2) (p. 88). Charles Lyell, Principles of Geology (4 vols.),
London, 1834. (p. 92). Ibid., vol. III., pp. 596-598. (4) (p. 100). Hugh
Falconer, in Paleontological Memoirs, vol. II., p. 596. (5) (p. 101).
Ibid., p. 598. (6) (p. 102). Ibid., p. 599. (7) (p. 111). Fossil Horses
in America (reprinted from American Naturalist, vol. VIII., May, 1874),
by O. C. Marsh, pp. 288, 289.
CHAPTER IV
THE ORIGIN AND DEVELOPMENT OF MODERN GEOLOGY
(1) (p. 123). James Hutton, from Transactions of the Royal Society of
Edinburgh, 1788, vol. I., p. 214. A paper on the "Theory of the Earth,"
read before the Society in 1781. (2) (p. 128). Ibid., p. 216. (3)
(p. 139). Consideration on Volcanoes, by G. Poulett Scrope, Esq., pp.
228-234. (4) (p. 153). L. Agassiz, Etudes sur les glaciers, Neufchatel,
1840, p. 240.
CHAPTER V
THE NEW SCIENCE OF METEOROLOGY
(1) (p. 182). Theory of Rain, by James Hutton, in Transactions of the
Royal Society of Edinburgh, 1788, vol. 1, pp. 53-56. (2) (p. 191). Essay
on Dew, by W. C. Wells, M.D., F.R.S., London, 1818, pp. 124 f.
CHAPTER VI
MODERN THEORIES OF HEAT AND LIGHT
(1) (p. 215). Essays Political, Economical, and Philosophical, by
Benjamin Thompson, Count of Rumford (2 vols.), Vol. II., pp. 470-493,
London; T. Cadell, Jr., and W. Davies, 1797. (2) (p. 220). Thomas Young,
Phil. Trans., 1802, p. 35. (3) (p. 223). Ibid., p. 36.
CHAPTER VII
THE MODERN DEVELOPMENT OF ELECTRICITY AND MAGNETISM
(1) (p. 235). Davy's paper before Royal Institution, 1810. (2) (p. 238).
Hans Christian Oersted, Experiments with the Effects of the Electric
Current on the Magnetic Needle, 1815. (3) (p. 243). On the Induction
of Electric Currents, by Michael Faraday, F.R.S., Phil. Trans. of Royal
Society of London for 1832, pp. 126-128. (4) (p. 245). Explication of
Arago's Magnetic Phenomena, by Michael Faraday, F.R.S., Phil. Trans.
Royal Society of London for 1832, pp. 146-149.
CHAPTER VIII
THE CONSERVATION OF ENERGY
(1) (p. 267). The Forces of Inorganic Nature, a paper by Dr. Julius
Robert Mayer, Liebig's Annalen, 1842. (2) (p. 272). On the Calorific
Effects of Magneto-Electricity and the Mechanical Value of Heat, by J.
P. Joule, in Report of the British Association for the Advancement of
Science, vol. XII., p. 33.
CHAPTER IX
THE ETHER AND PONDERABLE MATTER
(1) (p. 297). James Clerk-Maxwell, Philosophical Magazine for January
and July, 1860.
END OF VOL. III