Pattern and Progress on the Geological Stage 495
of state. (Eddington later gave elegant expression to this argument by describing
Kelvin's second law of thermodynamics as "time's arrow.")
Diplomatically perhaps, Kelvin attacked Hutton's earlier version of the
conflation (via Playfair's famous exegesis of 1802), rather than Lyell's
contemporary presentation. Kelvin quotes Playfair's (1802) most famous lines:
"The Author of nature has not given laws to the universe, which, like the
institutions of men, carry in themselves the elements of their own destruction. He
has not permitted in His works any symptoms of infancy, or of old age, or any sign
by which we may estimate either their future or their past duration." Kelvin
responds by demolishing this false rationale for a non-directional earth (Thompson,
1868, p. 2): "Nothing could possibly be further from the truth than this statement.
It is pervaded by a confusion between 'present order,' or 'present system,' and 'laws
now existing'—between destruction of the earth as a place habitable to beings such
as now live on it, and a decline or failure of law and order in the universe."
Later, in discussing the secular slowing of the earth's rotation due to tidal
friction imposed by the moon (a trend now supported empirically by evidence from
daily and yearly growth lines of fossil organisms), Kelvin strongly asserts that even
a small directional effect, measured as seconds of slowing per century, strongly
compromises the entire Lyellian system: "It is quite certain that a great mistake has
been made—that British popular geology at the present time is in direct opposition
to the principles of natural philosophy... There cannot be uniformity. The earth is
filled with evidences that it has not been going on forever in this present state, and
that there is progress of events towards a state infinitely different from the present"
(1868, p. 16).
Kelvin criticized Lyell more directly for his claim that heat lost by radiation
into space can always be reconstituted from other sources (chemical and
electrical)—for such an article of non-directional faith violates the second law of
thermodynamics: "These statements are directly opposed to the general principle of
the dissipation of energy: and the hypothesis which they suggest is very
inconsistent with our special knowledge of the conduction and radiation of heat, of
thermoelectric currents, of chemical action, and of physical astronomy" (1868, p.
231).
Kelvin then invokes his second law to identify the main vector of physical
change through time: as entropy and disorder increase, the energy of most causes
must diminish. Therefore, most geological processes must have acted with
substantially more vigor on the early earth, leading to an expectation for more
rapid biological change at this time, if changes in the physical world potentiate
biological evolution.
I earnestly beg Professor Huxley, and those in whose name he speaks, to
reconsider their opinion, that the secular cooling of the earth and of the sun
"had made no practical difference to the earth during the period of which a
record is preserved in stratified deposits." There is, surely, good ground for
Sir Roderick Murchison's opinion that metamorphic causes