Do you remember a visit paid to me by the celebrated chemist, Humphry Davy, in 1825 ?" "Not at all, for I was not born until nineteen years afterwards." "Well, Humphry Davy did call upon me on his way through Hamburg.

We were long engaged in discussing, amongst other problems, the hypothesis of the liquid structure of the terrestrial nucleus.

We were agreed that it could not be in a liquid state, for a reason which science has never been able to confute." [1] The degrees of temperature are given by Jules Verne according to the centigrade system, for which we will in each case substitute the Fahrenheit measurement.

(Tr.) "What is that reason ?" I said, rather astonished.
"Because this liquid mass would be subject, like the ocean, to the lunar attraction, and therefore twice every day there would be internal tides, which, upheaving the terrestrial crust, would cause periodical earthquakes!" "Yet it is evident that the surface of the globe has been subject to the action of fire," I replied, "and it is quite reasonable to suppose that the external crust cooled down first, whilst the heat took refuge down to the centre." "Quite a mistake," my uncle answered.

"The earth has been heated by combustion on its surface, that is all.