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, good-humoredly.
"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."
"Now sixteen is the hundredth part of our contemplated expedition. If we go on in this way we shall be two thousand days, that is about five years and a half, going down."
The Professor folded his arms, listened, but did not speak.
"Without counting that if a vertical descent of sixteen leagues costs us a horizontal of eighty-five, we shall have to go about eight thousand leagues to the southeast, and we must therefore come out somewhere in the circumference long before we can hope to reach the center."
"Bother your calculations," cried my uncle in one of his old rages. "On what basis do they rest? How do you know that this passage does not take us direct to the end we require? Moreover, I have in my favor, fortunately,
