On the Revolutions of the Celestial Spheres

ON THE REVOLUTIONS, BOOK I.

if it were even an eighth part Copernicus is refuting the traditional Aristotelian view that the volume of water was ten times that of land., its diameter could not be greater than the distance from the center to the surface of the waters; it is far from being ten times greater than the land. That there is also no difference between the center of gravity of the earth and the center of its magnitude can be understood from this: that the convexity of the earth spreading out from the ocean does not continuously swell as it recedes; otherwise, it would push back the sea waters as much as possible and would in no way allow inland seas or such vast gulfs to break through. Furthermore, the depth of the abyss would never cease to increase from the shore of the ocean, so that no island, nor rock, nor any piece of land would be encountered by sailors as they progressed further. Now, however, it is well known that between the Egyptian sea and the Arabian gulf The Isthmus of Suez. there remains barely fifteen stadia A stadium was an ancient unit of length, roughly 185 meters; Copernicus’s figure here is notably smaller than the actual distance, likely following ancient sources. in the very middle of the world. Conversely, Ptolemy in his Cosmography original: "Coſmographia"; today known as Ptolemy’s Geography. extended the habitable land to the middle circle, leaving beyond it unknown land where more recent explorers have added Cathay Northern China. and vast regions as far as 60 degrees of longitude. Thus, the land is now inhabited over a greater longitude than what remains for the ocean.

This will be even clearer if we add the islands found in our time under the Princes of Spain and Portugal, and especially America, named after its discoverer, the master of ships A reference to Amerigo Vespucci.. Because of its size, which is still not fully determined, they think it is another world, besides many other islands previously unknown. We should therefore not be surprised that there are Antipodes People living on the opposite side of the globe. or Antichthones original: "Antichthones"; a Greek term for "those on the opposite earth.". For geometric reasoning forces us to believe that America itself is situated diametrically opposite to India on the Ganges. From all these things, I think it is manifest that land and water together lean upon one center of gravity, and that there is no other center of magnitude for the earth; and since the earth is heavier, its gaping parts are filled with water. Therefore, there is a small amount of water in comparison with the earth, even if on the surface more water perhaps appears.

For it is necessary that the earth, with its surrounding waters, have the same shape that its shadow reveals; for it produces the darkening of the Moon by the circumferences of a perfect circle. Therefore, the earth is not flat, as Empedocles and Anaximenes thought; nor drum-shaped, as Leucippus held; nor boat-shaped, as Heraclitus believed; nor hollow in any other way, as Democritus suggested. Nor is it cylindrical, as Anaximander claimed; nor infinite in its thickness downward from its lower part, as Xenophanes supposed; but it is of absolute roundness, as the Philosophers believe.