"Scientific men claim that the atmosphere is forty-five geographical miles in depth over the earth's surface," I said.
"If the earth is eight thousand miles in diameter, how long would such an atmosphere, a skin only, over a great ball, resist such attraction, and remain above the globe? Were it really attracted towards its center it would disappear as a film of water sinks into a sponge."
"Do you know," I interrupted, "that if these statements were made to men they would not be credited? Scientific men have calculated the weights of the planets, and have estimated therefrom the density of the earth, showing it to be solid, and knowing its density, they would, on this consideration alone, discredit your story concerning the earth shell."
[Illustration: THE EARTH AND ITS ATMOSPHERE.
The space between the inner and the outer lines represents the atmosphere upon the earth. The depth to which man has penetrated the earth is less than the thickness of either line, as compared with the diameter of the inner circle.]
"You mistake, as you will presently see. It is true that man's ingenuity has enabled him to ascertain the weights and densities of the planets, but do you mean to say that these scientific results preclude the possibility of a hollow interior of the heavenly bodies?"
"You should know then, that what men define as density of the earth, is but an average value, which is much higher than that exhibited by materials in the surface layers of the earth crust, such as come within the scrutiny of man. This fact allows mortals of upper earth but a vague conjecture as to the nature of the seemingly much heavier substances that exist in the interior of the earth. Have men any data on hand to show exactly how matter is distributed below the limited zone that is accessible to their investigations?"
"You may safely accept, then, that the earth shell I have described to you embraces in a compact form the total weight of the earth. Even though men take for granted that matter fills out the whole interior of our planet, such material would not, if distributed as on earth's surface, give the earth the density he has determined for it."
"Let us now go a step further in this argument. What do you imagine is the nature of those heavier substances whose existence deep within the earth is suggested by the exceedingly high total density observed by man on upper earth?"