To many, the question of gravity seems a great argument against the theory that the earth is hollow. This undoubtedly arises from the fact that gravity is supposed to be something located in the centre of the earth, drawing everything in that direction, or to the centre. Philosophy teaches that the greater attracts the lesser. If the earth is hollow, and the walls are, say, a thousand miles thick, why should not the centre of the walls be the centre of attraction, as well as of the earth, if solid? If gravity is something that repels ether, or air, above the earth, then it would make no difference whether the earth were concave or convex.
Again: if the centre of the walls of the earth is the centre of gravity, then the greatest attraction would be at the poles, where it is found to be. Nansen's description of the dead water, it will be remembered, is: "We could hardly get on at all, for the dead water, and we swept the whole sea along with us. It is a peculiar phenomenon--this dead water. We had at present a better opportunity of studying it than we desired. It occurs where a surface layer of fresh water rests upon the salt water of the sea, and this fresh water is carried along with the ship, gliding on the heavier sea water beneath, as if on a fixed foundation."
The centre of gravity seems strongest here, and was probably about midway round the curve on Nansen's way to the interior of the earth. If this be true, it is in accordance with the wisdom of the Creator: the greatest attraction where it is most needed. The laws of the universe are inevitable; when they seem otherwise we do not understand them.
The question of gravity is most puzzling, and, so far as I know, not understood. I desire to show that, be the earth hollow or solid, gravity is not in any way affected. If gravity is something that acts as a magnet, and draws everything to
the centre, the walls of the earth would then be the magnet. On the other hand, if gravity is something above the earth that repels--air or ether--then the earth's shape would in nowise affect it. I believe it will be found that gravity is strongest at the turning point entering the interior of the earth, and objects will weigh more at that point than near the equator or in the interior of the earth. Every substance will then appear lighter or weigh less in the interior of the earth, for the reason that the laws of the universe are so perfect that nothing is wasted, and a substance requires less force to hold it to the inside of a hollow ball in motion than to hold it to the outside.