Even though there are many versions of the precise wording of this impromptu exchange, Huxley’s oratorical skills and the rising sentiments against the interference of men of the church with science have helped this legend grow. Historian of science James Moore even went so far as to state, “No battle of the nineteenth century, since Waterloo, is better known.”

Huxley decided to come to the geologists’ defense in his 1869 presidential address to the Geological Society of London. First, he took advantage of the fact that Kelvin’s condemnation happened to be directed at the rather old text by Playfair to make the questionable claim “I do not suppose that, at the present day any geologists would be found to maintain absolute Uniformitarianism.” He continued by asking rhetorically whether any geologist had ever required more than one hundred million years for the action of geology. This was really a sleight of hand, since Huxley’s own “master,” Darwin himself, wrongly estimated an age of three hundred million years for the Weald. Finally, after a few more dubious, if eloquent, assertions, Huxley pronounced his own summary that “the case against [geology and biology] has entirely broken down.”

Huxley’s address drew a furious response from one of Kelvin’s most staunch supporters: Peter Guthrie Tait. The mathematician, who never missed an opportunity for a good fight, wrote a review of Kelvin’s and Huxley’s addresses in which he wrapped insults directed at Huxley in a few polite sentences. Then, to deliver an even more punishing blow, Tait decided to cite a number for the age of the Earth that not only had no physical justification whatsoever but also was even shorter than Kelvin’s most extreme estimates:

We find that we may, with considerable probability, say that Natural Philosophy already points to a period of some ten or fifteen millions of years as all that can be allowed for the purpose of the geologist and paleontologist; and that it is not unlikely that, with better experimental data, this period may be still further reduced.

The net result of Tait’s provocative statements was an increasing sense of discontent among the geologists, who felt that in spite of their efforts to come to terms with Kelvin’s limitations, the physicists were not reciprocating by any concessions to geological evidence. These details notwithstanding, however, there was no question that, conceptually at least, Kelvin had won the battle, and the notion of a limited rather than immeasurable time for the age of the Earth had triumphed. By the end of the nineteenth century, the idea of a steady state Earth had given way to the realization that calculating the age of the Earth using physical principles was part of what geology was all about.