Physiologia Kircheriana Experimentalis

there will be no difference between the right, left, oblique, upper, and lower parts. Furthermore, in whatever direction it is turned, it will always remain at rest in that position, since it does not incline toward one side rather than another, but is indifferent to every position in which it may be placed.

Corollary I.

Hence it follows that if the scoops of a water wheel, which normally stand upright, were filled with water, that wheel, when rotated, would spill none of the water it contains, since all the scoops point straight toward the center.

Corollary II.

Hence it also follows how—a thing which many of the ancient Fathers could not conceive—the antipodes move in a natural position with their feet opposite to ours.

Let there be a terrestrial globe A B C D: let there be antipodes, F and S, who walk with their feet turned toward us. I say that they walk in a natural position, because both incline toward the center H through the lines of direction F D and S D at opposite parts. The same must be understood regarding ships, since they verge from every side and direction toward the center of the earth along the lines of direction under which they are carried; nor, as the simpler folk falsely imagine for themselves, is the falling of men or ships in the parts opposite to us to be feared. If, therefore, some of the ancients had known the nature of the center, they would not have reasoned so inexpertly about the earth, I know not what abyss and whirlpool, which they imagined to be below their horizon.

They would have reasoned [otherwise] about the earth, and not about I know not what abyss and whirlpool, which they imagined to be beneath the horizon.

PARADOX VII.

At the center of the earth, two men tending toward opposite sides naturally ascend.

Let a ladder B C be applied at the center of the earth A. I say that from the center A, two men—of whom one ascends from A toward B, and the other from A toward C—ascend at one and the same time; even though each ascends toward opposite parts A and B, they nevertheless ascend naturally. The reason is evident from the thing itself, as the ladder, when moved in any direction, will have its natural position there.

PARADOX VIII.

The flight of any bird around the center of the earth will be most easy and natural, either in a circular path or along the line of a helix; any other motion will be violent.

Any bird will move around the center of the earth with a natural and easy motion when it moves along the line of a circle or a helix, as is evident in circle A, which the bird describes in its flight, because in this way it will sustain no violent motion, which happens to those—it must be said—that, since it consists of a circular and a sloping path, it will greatly accelerate the flight, nor