Underground Rivers - University of New Mexico

Chapter 10 -- Geophysical, Pnuematic and Electromagnetic Engines
The first physically-based theory of the separation of sea and land was a marvelous exercise of
human intellect. Jean Buridan (1295-1358) was a disciple of William of Ockham, remembered for
the principle of ontological parsimony, Ockham’s Razor.
Entia non sunt multiplicanda praeter necessitatem.
When competing explanations seem equally plausible, the simpler is more likely to be correct.
In Compendium totius Logicae, Buridan proposed that the earth is asymmetric, such that land
occupies most of one hemisphere and oceans occupy primarily the other (plausible, given the
geographic knowledge of the day). The geocentric requirement of his times -- that the earth lies
at the center of the universe -- posed a problem, however, as sediment accumulation at the
bottom of the sea would shift the earth’s center of mass. To remain universally centered, the
earth must thus shift as a whole towards the land hemisphere, raising it out of the water and thus
rebuilding the mountains.
Albert of Saxony (1316-1390), primarily a logician (as opposed to a natural philosopher) extended
the offset-spheres model. Appealing to the authority of his “revered masters from the Faculty of
Arts at Paris,” his Quaestiones in Aristotelis Libros de Caelo et Mundo explained earthquakes,
tidal phenomena, and geology in terms of an “asymmetry preordained by God since eternity for
the good of animals and plants.”
Da Vinci's off-center geosphere didn't require God's ordination. The figure below, a labeled
version of the sketch he used to illustrate the idea, shows why the sea remains offshore, and why
the pipe is downhill from ocean to mountain slope.
Continent
Land Surface
Sea Level
Center of Terrestrial Globe
Downhill Pipe to
Center of Sphere of Water Mountaintop
Sea Floor
Ocean Surface
Sea
Perhaps you will say that water can only rise the same distance as it descends; and that the
surface of the sea is higher than the summits of the highest mountains. The answer to this is
that the exact opposite is the case, for the lowest part visible to the sky is the surface of the
sea, since water does not move of itself unless to descend, and so descends when it moves; as
therefore the rivers which stretch from the summits of the mountains to the sea are everywhere
in movement they are therefore everywhere descending, and when they come to the sea they
stop and end their movement; for which reason one must conclude that they arc stationary in
the lowest reaches of the river.
In another twist of the higher-than argument, da Vinci argued,
The Mediterranean Sea, a vast river placed between Africa, Asia, and Europe, gathers within
itself about three hundred principal rivers, and in addition to that it receives the rains which fall
upon it over a space of three thousand miles. It returns to the mighty ocean its own waters and
those that it has received; but doubtless it returns less to the sea than what it receives; for from
it descend many springs which flow through the bowels of the earth and vivify this terrestrial
machine. This is so because the surface of this Mediterranean is farther from the centre of the
world than the surface of this ocean.
It would take the simplicity of Newtonian physics to explain that even if the earth were
asymmetrical (which to some degree it is), there's only one downhill direction.
DRAFT 1122//66//22001122
Uppddaatteess aatt hhttttpp::////www. .uunnm. .eedduu//~rrhheeggggeenn//UnnddeerrggrroouunnddRi ivveerrss. .hhttml l
92