Physiologia Kircheriana Experimentalis

Therefore, it should be no wonder that a man is so greatly fatigued in the ascent of steep mountains. But what we have said concerning bridges to be constructed immediately around the center of the earth, the same must be said of similar structures to be built in the air around the surface of the earth. But let us demonstrate the matter. Let there be, by divine power, around the surface of the earth E B D, a triangular bridge A B C D F E; let lines of direction now be drawn toward the outer surface of the bridge; it is certain that a man progressing from B toward A would continuously ascend as if up a very high mountain, nor could he stand upright in any place except at points E, B, and D, where the line of direction falls normally upon the sides of the bridge; but in his progress, as the lines of direction between B and A show, he can no longer stand upright on the plane of the bridge, nor will the lines of direction fall normally upon the sides of the bridge any longer, but they will form angles with the sides of the bridge that are the more acute the closer they approach the apex A. Hence it happens that a man, in order to sustain himself under the disposition of the central line, must stand with his body inclined toward the slope and on the extreme tips of his toes, since on the slope of a mountain it is impossible to stand upright without danger of falling.

Corollary.

From this it is evident that at the center of the earth, no structure suitable for human use can exist, except one that is circular.

PARADOX II.

Fire, water, sand, and other liquid bodies at the center of the earth will presently conform themselves into a sphere.

Let a great quantity of water be brought by divine power through a channel into the center of the earth; I say that it will presently conform itself into a sphere at the center of the earth. For since the center of gravity of any homogeneous sphere, as we have shown in the first canon, is the same as the center of magnitude of the sphere, it is certain that water cannot consist otherwise than under the form of a watery globe; for let it consist, if it be possible, under the form of a square or any other figure whatsoever; therefore, the water in this state will stand around the corners of the square, against nature, and violently; but this is absurd; therefore it will necessarily conform itself into a globe, for in this position, the individual parts inclining toward the center with equal force will sustain themselves most perfectly, and will consist balanced on every side. The same must be said of fluid sand.

Corollary of Experiment I.

From this it follows that if four different kinds of liquids, which represent the four elements by their gravity, just as we have taught should be done in Ars Magnetica, are introduced into a spherical vial, experience teaches that the said liquids on the surface of the earth will lie parallel to the horizon, one resting upon another; so that the heaviest, which represents the earth, will take the lowest place; the second, of an airy color, representing water, the second—