Last week’s blog post was about Copernicus and how he rejected the Two Spheres Theory (TST) regarding the shape of our world—that body we now call Planet Earth. As discussed in that post, the TST supposed that the world was composed of two spheres of material: an earthy sphere and a water sphere, with the earthy sphere bulging out from the watery sphere as shown at right.
There were a variety of ways by which this was explained. Copernicus cites one in On the Revolutions—the idea that the earthy sphere has cavities within it, and thus apparently is buoyed by the water sphere. David Wootton devotes a chapter to the Two Spheres Theory in his 2015 book The Invention of Science,* and notes other ways of explaining the TST. One of these, he says, was that
...the waters have been displaced from their original position, and their sphere now has a centre other than the centre of the universe. This view implies that ships sail uphill as they sail out on the ocean.... In 1320 Dante took it to be the standard view....
In other words, if
1) the center of the earthy sphere is the center of the universe, that is, the lowest place in the universe, and
2) the water sphere is off-center to the earthy sphere
then it follows that
3) some points on the water sphere would be farther from the center of the universe—that is, higher—than dry land. The ocean would be higher than the land.
This serves to explain a natural phenomenon—springs! Especially big springs! And extra especially big springs in the middle of the desert or high up on a mountain. What could feed a big spring that supplies a desert oasis? There is no rain. There must be cracks in the earthy sphere that allow water from the ocean to work its way through, water that is under pressure and rises up from the ground owing to the fact that the ocean is higher than the land and water seeks its own level. Wootton notes that even after the discovery of America and the collapse of the TST (see last week’s post), the idea persisted that the seas are higher than the land.
This idea was something people knew about. For instance, in the 1688 book Familiar Letters, Domestic and Forren, by James Howell, can be found a letter of April 1, 1617 from James to his brother, in which he writes—
I am newly landed at Amsterdam, and it is the first forren Earth I ever set Foot upon: I was pittifully Sick all the Voyage, for the Weather was rough, and the Wind untoward; and at the mouth of the Texel we were surprised by a furious Tempest…. Having bin so rocked and shaken at Sea, when I came ashore I began to incline to Copernicus his Opinion, which hath got such a sway lately in the World, viz. That the Earth, as well as the rest of her fellow-Elements, is in perpetual Motion; for she seem’d so to me a good while after I had landed. He that observes the site and position of this Country, will never hereafter doubt the truth of that Philosophical Problem which keeps so great a noise in the Schools,* viz. That the Sea is higher than the Earth; because, as I sailed along these Coasts, I visibly found it true; for the Ground here, which is all 'twixt Marsh and Moorish, lies not onely level, but to the apparent sight of the Eye, far lower than the Sea; which made the Duke of Alva say, That the Inhabitants of this Country were the nearest Neighbours to Hell of any People upon Earth, because they dwell lowest.
But if water seeks its own level, what keeps the oceans higher than the lands so that their waters feed the springs? Why don’t the waters of the ocean flow over the land? The answer: the hand of God. That is the subject of next week’s post.
*For the ideas from Wootton’s book cited in this post, see the UK version of the book, pages 113 and 129. The boldface emphasis in the Howell quote is added.