The porches or verandas are all without, and are secondary.

The building is really constructed for the conveniences within.
Olaf Jansen makes the startling announcement through me, an humble instrument, that in like manner, God created the earth for the "within"-- that is to say, for its lands, seas, rivers, mountains, forests and valleys, and for its other internal conveniences, while the outside surface of the earth is merely the veranda, the porch, where things grow by comparison but sparsely, like the lichen on the mountain side, clinging determinedly for bare existence.
Take an egg-shell, and from each end break out a piece as large as the end of this pencil.

Extract its contents, and then you will have a perfect representation of Olaf Jansen's earth.

The distance from the inside surface to the outside surface, according to him, is about three hundred miles.

The center of gravity is not in the center of the earth, but in the center of the shell or crust; therefore, if the thickness of the earth's crust or shell is three hundred miles, the center of gravity is one hundred and fifty miles below the surface.
In their log-books Arctic explorers tell us of the dipping of the needle as the vessel sails in regions of the farthest north known.