“Would you then conclude,” I said, “that the magnetic pole is somewhere between the surface of the globe and the point where we are?”

“Exactly so; and it is likely enough that if we were to reach the spot beneath the polar regions, about that seventy-first degree where Sir James Ross has discovered the magnetic pole to be situated, we should see the needle point straight up. Therefore that mysterious centre of attraction is at no great depth.”

I remarked: “It is so; and here is a fact which science has scarcely suspected.”

“Science, my lad, has been built upon many errors; but they are errors which it was good to fall into, for they led to the truth.”

“What depth have we now reached?”

“We are thirty-five leagues below the surface.”