"And that whales are playing in shoals, thrashing the bottom of the sea, the roof of our adamantine prison?" "Be quite at rest on that point; there is no danger of their breaking through. But to return to our calculations. We are to the southeast, two hundred and fifty miles from the base of Sneffels, and, according to my preceding notes, I think we have gone sixteen leagues in a downward direction." "Sixteen leagues--fifty miles!" I cried. "I am sure of it." "But that is the extreme limit allowed by science for the thickness of the earth's crust," I replied, referring to my geological studies. "I do not contravene that assertion," was his quiet answer. "And at this stage of our journey, according to all known laws on the increase of heat, there should be here a temperature of <i>fifteen hundred degrees of Reaumur</i>." "There should be--you say, my boy." "In which case this granite would not exist, but be in a state of fusion." "But you perceive, my boy, that it is not so, and that facts, as usual, are very stubborn things, overruling all theories." "I am forced to yield to the evidence of my senses, but I am nevertheless very much surprised." "What heat does the thermometer really indicate?" continued the philosopher. "Twenty-seven six-tenths." "So that science is wrong by fourteen hundred and seventy-four degrees and four-tenths. According to which, it is demonstrated that the proportional increase in temperature is an exploded error. Humphry Davy here shines forth in all his glory. He is right, and I have acted wisely to believe him. Have you any answer to make to this statement?" Had I chosen to have spoken, I might have said a great deal. I in no way admitted the theory of Humphry Davy--I still held out for the theory of proportional increase of heat, though I did not feel it. I was far more willing to allow that this chimney of an extinct volcano was covered by lava of a kind refractory to heat--in fact a bad conductor--which did not allow the great increase of temperature to percolate through its sides. The hot water jet supported my view of the matter. But without entering on a long and useless discussion, or seeking for new arguments to controvert my uncle, I contented myself with taking up facts as they were. "Well, sir, I take for granted that all your calculations are correct, but allow me to draw from them a rigorous and definite conclusion." "Go on, my boy--have your say," cried my uncle goodhumoredly. "At the place where we now are, under the latitude of Iceland, the terrestrial depth is about fifteen hundred and eighty-three leagues." "Fifteen hundred eighty-three and a quarter." "Well, suppose we say sixteen hundred in round numbers. Now, out of a voyage of sixteen hundred leagues we have completed sixteen." "As you say, what then?" "At the expense of a diagonal journey of no less than eighty-five leagues." "Exactly." "We have been twenty days about it." "Exactly twenty days."