ON THE EARTH’S CLIMATE IN PALAEOZOIC TIMES. | To Dr. John Tyndall, F.R.S., &c. | Montreal, February 1, 1864.
My Dear Sir,
IN a Note which appeared in the Philosophical Magazine for October 1863 (page 323),2 I endeavoured to explain the warmer climate of the earth in palaeozoic times by the aid of your remarkable researches on radiant heat, by which you have shown that small quantities of various gases, when diffused in the atmosphere, greatly retard cooling by radiation. I suggested that the large amount of carbon which was then diffused in the atmosphere as carbonic acid, and which has since been separated in the forms of carbonate of lime and carboniferous matters, must have had a powerful influence upon the temperature of the earth’s surface during the palaeozoic period; I also indicated the influence of marsh-gas from the decay of the abundant vegetation of the period. I was not at the time aware that my suggestions had been anticipated by you in the [Bakerian] Lecture for 1861,3 where you say that, from its influence on terrestrial radiation, all variation in the amount of aqueous vapour in the atmosphere must produce changes in climate; and you then add, “Similar remarks would apply to the carbonic acid diffused through the air, while an almost inappreciable admixture of any of the hydrocarbon vapours would produce great effects on the terrestrial rays, and corresponding changes of climate. It is not, therefore, necessary to assume alterations in the density and height of the atmosphere to account for the different amounts of heat being preserved to the earth at different times; a slight change in its variable constituents would account for this. Such changes, in fact, may have produced all the mutations of climate which the researches of geologists reveal.” (Philosophical Magazine, Oct. 1861, p.277)
In the American Journal of Science for November 1863 (p.398), I have in this connexion referred to a paper by the late Major E.B. Hunt,4 United States Engineers, “On Terrestrial Thermotics,”5 published in the Proceedings of the American Association for the Advancement of Science for 1849. In this paper Major Hunt argues that the temperature of the earth’s surface increases with the weight of the barometric column, and that, as the atmospheric mass must have been greater in the earlier geological periods by the amount of carbon and of carbonic acid since abstracted, the temperature of the earth must then have been higher. To this mass Prof. Dana6 would add the abundant moisture of the insular climate of former times. The augmentation of barometric pressure dependent upon these additions to the atmosphere would, however, probably be very inadequate to explain the considerable differences in climate of which geology affords us evidence; and it is only in the light of your recent discoveries that the chemical constitution of the early atmosphere of our globe enables us to explain the warmth of ancient climates.
The object which I have in writing this note is thus not only to set forth major Hunt’s early attempts to solve the problem, but to call public attention to the fact that what I conceive to be its true solution was first suggested by yourself.
I have honour to be, my dear Dr. Tyndall, | Very faithfully yours, | T. Sterry Hunt.
Phil. Mag., 27 (1864), pp. 236–7
Thomas Sterry Hunt: Thomas Sterry Hunt (1826-1892), an American geologist and chemist (ADB).
Note which appeared… (page 323): T. S. Hunt, ‘On the Earth’s Climate in Palaeozoic Times,’ Phil. Mag., 26 (1863), pp. 323–4.
the [Bakerian] Lecture for 1861: J Tyndall, ‘On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connexion of Radiation, Absorption, and Conduction’, Phil. Trans., 151 (1861),pp. 1–36 (read at the RS on 7 February 1861; Hunt was referring to pp. 28–9).
Major E. B. Hunt: Edward Bissell Hunt (1822–63), an American engineer who died of suffocation as the result of an accident, while engaged in the prosecution of investigations incident to his profession, and immediately connected with the American Civil War. Hunt worked primarily on rocket torpedoes (G. W. Cullum, Biographical Register of the Officers and Graduates of the U.S. Military Academy at West Point, N.Y., 3rd edn, 3 vols (Boston and New York: Houghton, Mifflin and Company, 1891), vol. 2, p. 209).
“On Terrestrial Thermotics”: E. B. Hunt, ‘Remarks on Terrestrial Thermotics’, in Proceedings of the American Academy for the Advancement of Science. Second Meeting, held at Cambridge, August, 1849 (Boston: Henry Flanders & Co., 1850), pp. 135–40.
Prof. Dana: James Dwight Dana (1813–95), an American geologist, mineralogist, volcanologist, and zoologist. He made pioneering studies of mountain-building, volcanic activity, and the origin and structure of continents and oceans around the world. Dana was the author of System of Mineralogy (1837), Manual of Mineralogy (1848), and Manual of Geology (1863) (ANB).
Please cite as “Tyndall2067,” in Ɛpsilon: The John Tyndall Collection accessed on