“Yes; according to a rather obscure law. It is well known that the weight of bodies diminishes as fast as we descend. You know that it is at the surface of the globe that weight is most sensibly felt, and that at the centre there is no weight at all.”

“I am aware of that; but, tell me, will not air at last acquire the density of water?”

“Of course, under a pressure of seven hundred and ten atmospheres.”

“And how, lower down still?”

“Lower down the density will still increase.”

“But how shall we go down then.”

“Why, we must fill our pockets with stones.”

“Well, indeed, my worthy uncle, you are never at a loss for an answer.”