Internal Heat of the Earth

The increase of temperature observed is about one degree Farenheit [sic] for every fifteen yards of descent, in all probability however, the increase will be found to be in a geometrical progression as investigation is extended in which case the present crust will be found to be much thinner than we have calculated it to be. And should this be found to be correct, the igneous theory will become a subject of more importance, in geological point of view, than we are at present disposed to consider it. Taking then, as correct, the present observed rate of increase, the temperature would be as follows: Water will boil at the depth of 8,400 yards. There is red heat at the depth of 7 miles. Gold melts at 21 miles. Cast Iron at 74 miles. Soft Iron at 97 miles. And at the depth of 100 miles there is a temperature equal to the greatest artificial heat yet observed; a temperature capable of fusing platina, porcelain, and indeed every refractory substance we are acquainted with. These Temperatures are calculated from Guyton [Morveau’s] corrected scale of Wedgewood’s [sic] pyrometer, and if we adopt them we find that the earth is fluid at the depth of 100 miles from the surface, and then even in its present state very little for than the soil on which we tread is fit for the habitation of organized beings.

– Published in the Stark County News, Toulon, Illinois, March 12, 1863