Underground Rivers - University of New Mexico

Chapter 12 -- Superterranean Metrics
We'll catch up with brother, Charles (1628-1703), in Chapter 17, Underground Rivers in
Continental Fiction for his contribution ot the study of underground streams in Tales of Mother
Goose (1697).
Edmé Mariotte (1620-1684) refuted the yet-popular assumption of
springs derived from condensation in subterranean caverns, as
precipitation could not penetrate more than a few meters into the
earth.
From Mariotte's Traité du Mouvement des Eaux et des Autres Corps
Fluides (1686),
For if ABC is a vault in the mountain DEF; it is evident,
that if the vapor should become water in the concave of
the surface ABC, that water would fall perpendicularly
towards HGI, and not towards T or M, and consequently
would never make a spring. Besides, it is denied that
there are many such hollow places in mountains, and it
can't be made appear that there are such. If we say
there is earth on the side of, and beneath ABC, it will be
answered, that the vapor will gush out at the sides
towards A and C, and that very little will become water;
and because it appears that there is almost always clay
where there are springs, it is very likely that those
supposed distilled waters can't pass through, and
consequently that springs can't be produced by that
means.
More simply: We won't find subterranean reservoirs behind springs.
To establish that the source of groundwater must be precipitation, Mariotte compared seepage
into the cellar of the Paris Observatory to the rainfall above, noting that more water came into the
basement after heavy rains.
[Rainfall} filtered through the soil until it met with impervious layers in then interior, through
which it was unable to pass; it therefore continued its course along them in an oblique direction
until it found egress and came out as springs.
Scientifically better educated that Perrault, Mariotte sought to confirm Perrault’s result using a
much larger catchment, that of the Seine at Paris.
It is thus evident that when a third of the rain waters have evaporated, a third will keep the soil
moist in the large plains, and a third will still b e sufficient to feed springs and rivers.
As Perrault’s and Mariotte’s studies were close in both time and location, it is informative to
compare their findings.
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