The Notebooks of Leonardo Da Vinci — Complete
rotundity, excepting in places where the sea is, or marshes or other
still waters. And every part of the earth that rises above the water
is farther from the centre.
935.
OF THE SEA WHICH CHANGES THE WEIGHT OF THE EARTH.
The shells, oysters, and other similar animals, which originate in
sea-mud, bear witness to the changes of the earth round the centre
of our elements. This is proved thus: Great rivers always run
turbid, being coloured by the earth, which is stirred by the
friction of their waters at the bottom and on their shores; and this
wearing disturbs the face of the strata made by the layers of
shells, which lie on the surface of the marine mud, and which were
produced there when the salt waters covered them; and these strata
were covered over again from time to time, with mud of various
thickness, or carried down to the sea by the rivers and floods of
more or less extent; and thus these layers of mud became raised to
such a height, that they came up from the bottom to the air. At the
present time these bottoms are so high that they form hills or high
mountains, and the rivers, which wear away the sides of these
mountains, uncover the strata of these shells, and thus the softened
side of the earth continually rises and the antipodes sink closer to
the centre of the earth, and the ancient bottoms of the seas have
become mountain ridges.
936.
Let the earth make whatever changes it may in its weight, the
surface of the sphere of waters can never vary in its equal distance
from the centre of the world.
Of the proportion of the mass of water to that of the earth (937.
938).
937.
WHETHER THE EARTH IS LESS THAN THE WATER.
Some assert that it is true that the earth, which is not covered by
water is much less than that covered by water. But considering the
size of 7000 miles in diameter which is that of this earth, we may
conclude the water to be of small depth.
938.
OF THE EARTH.
The great elevations of the peaks of the mountains above the sphere
of the water may have resulted from this that: a very large portion
of the earth which was filled with water that is to say the vast
cavern inside the earth may have fallen in a vast part of its vault
towards the centre of the earth, being pierced by means of the
course of the springs which continually wear away the place where
they pass.
Sinking in of countries like the Dead Sea in Syria, that is Sodom
and Gomorrah.
It is of necessity that there should be more water than land, and
the visible portion of the sea does not show this; so that there
must be a great deal of water inside the earth, besides that which
rises into the lower air and which flows through rivers and springs.
[Footnote: The small sketch below on the left, is placed in the
original close to the text referring to the Dead Sea.]
The theory of Plato.
939.
THE FIGURES OF THE ELEMENTS.
Of the figures of the elements; and first as against those who deny
the opinions of Plato, and who say that if the elements include one
another in the forms attributed to them by Plato they would cause a
vacuum one within the other. I say it is not true, and I here prove
it, but first I desire to propound some conclusions. It is not
necessary that the elements which include each other should be of
corresponding magnitude in all the parts, of that which includes and
of that which is included. We see that the sphere of the waters
varies conspicuously in mass from the surface to the bottom, and
that, far from investing the earth when that was in the form of a
cube that is of 8 angles as Plato will have it, that it invests the
earth which has innumerable angles of rock covered by the water and
various prominences and concavities, and yet no vacuum is generated
between the earth and water; again, the air invests the sphere of
waters together with the mountains and valleys, which rise above
that sphere, and no vacuum remains between the earth and the air, so
that any one who says a vacuum is generated, speaks foolishly.
But to Plato I would reply that the surface of the figures which
according to him the elements would have, could not exist.
That the flow of rivers proves the slope of the land.
940.
PROVES HOW THE EARTH IS NOT GLOBULAR AND NOT BEING GLOBULAR CANNOT
HAVE A COMMON CENTRE.
We see the Nile come from Southern regions and traverse various
provinces, running towards the North for a distance of 3000 miles
and flow into the Mediterranean by the shores of Egypt; and if we
will give to this a fall of ten braccia a mile, as is usually
allowed to the course of rivers in general, we shall find that the
Nile must have its mouth ten miles lower than its source. Again, we
see the Rhine, the Rhone and the Danube starting from the German
parts, almost the centre of Europe, and having a course one to the
East, the other to the North, and the last to Southern seas. And if
you consider all this you will see that the plains of Europe in
their aggregate are much higher than the high peaks of the maritime
mountains; think then how much their tops must be above the sea
shores.
Theory of the elevation of water within the mountains.
941.
OF THE HEAT THAT IS IN THE WORLD.
Where there is life there is heat, and where vital heat is, there is
movement of vapour. This is proved, inasmuch as we see that the
element of fire by its heat always draws to itself damp vapours and
thick mists as opaque clouds, which it raises from seas as well as
lakes and rivers and damp valleys; and these being drawn by degrees
as far as the cold region, the first portion stops, because heat and
moisture cannot exist with cold and dryness; and where the first
portion stops the rest settle, and thus one portion after another
being added, thick and dark clouds are formed. They are often wafted
about and borne by the winds from one region to another, where by
their density they become so heavy that they fall in thick rain; and
if the heat of the sun is added to the power of the element of fire,
the clouds are drawn up higher still and find a greater degree of
cold, in which they form ice and fall in storms of hail. Now the
same heat which holds up so great a weight of water as is seen to
rain from the clouds, draws them from below upwards, from the foot
of the mountains, and leads and holds them within the summits of the
mountains, and these, finding some fissure, issue continuously and
cause rivers.
The relative height of the surface of the sea to that of the land
(942-945).
942.
OF THE SEA, WHICH TO MANY FOOLS APPEARS TO BE HIGHER THAN THE EARTH
WHICH FORMS ITS SHORE.
_b d_ is a plain through which a river flows to the sea; this plain
ends at the sea, and since in fact the dry land that is uncovered is
not perfectly level--for, if it were, the river would have no
motion--as the river does move, this place is a slope rather than a
plain; hence this plain _d b_ so ends where the sphere of water
begins that if it were extended in a continuous line to _b a_ it
would go down beneath the sea, whence it follows that the sea _a c
b_ looks higher than the dry land.
Obviously no portions of dry land left uncovered by water can ever
be lower than the surface of the watery sphere.
943.
OF CERTAIN PERSONS WHO SAY THE WATERS WERE HIGHER THAN THE DRY LAND.
Certainly I wonder not a little at the common opinion which is
contrary to truth, but held by the universal consent of the judgment
of men. And this is that all are agreed that the surface of the sea
is higher than the highest peaks of the mountains; and they allege
many vain and childish reasons, against which I will allege only one
simple and short reason; We see plainly that if we could remove the
shores of the sea, it would invest the whole earth and make it a
perfect sphere. Now, consider how much earth would be carried away
to enable the waves of the sea to cover the world; therefore that
which would be carried away must be higher than the sea-shore.
944.
THE OPINION OF SOME PERSONS WHO SAY THAT THE WATER OF SOME SEAS IS
HIGHER THAN THE HIGHEST SUMMITS OF MOUNTAINS; AND NEVERTHELESS THE
WATER WAS FORCED UP TO THESE SUMMITS.
Water would not move from place to place if it were not that it
seeks the lowest level and by a natural consequence it never can
return to a height like that of the place where it first on issuing
from the mountain came to light. And that portion of the sea which,
in your vain imagining, you say was so high that it flowed over the
summits of the high mountains, for so many centuries would be
swallowed up and poured out again through the issue from these
mountains. You can well imagine that all the time that Tigris and
Euphrates
945.
have flowed from the summits of the mountains of Armenia, it must be
believed that all the water of the ocean has passed very many times
through these mouths. And do you not believe that the Nile must have
sent more water into the sea than at present exists of all the
element of water? Undoubtedly, yes. And if all this water had fallen
away from this body of the earth, this terrestrial machine would
long since have been without water. Whence we may conclude that the
water goes from the rivers to the sea, and from the sea to the
rivers, thus constantly circulating and returning, and that all the
sea and the rivers have passed through the mouth of the Nile an
infinite number of times [Footnote: _Moti Armeni, Ermini_ in the
original, in M. RAVAISSON'S transcript _"monti ernini [le loro
ruine?]"_. He renders this _"Le Tigre et l'Euphrate se sont deverses
par les sommets des montagnes [avec leurs eaux destructives?] on
pent cro're" &c. Leonardo always writes _Ermini, Erminia_, for
_Armeni, Armenia_ (Arabic: _Irminiah_). M. RAVAISSON also deviates
from the original in his translation of the following passage: "_Or
tu ne crois pas que le Nil ait mis plus d'eau dans la mer qu'il n'y
en a a present dans tout l'element de l'eau. Il est certain que si
cette eau etait tombee_" &c.]
II.
ON THE OCEAN.
Refutation of Pliny's theory as to the saltness of the sea (946.
947).
946.
WHY WATER IS SALT.
Pliny says in his second book, chapter 103, that the water of the
sea is salt because the heat of the sun dries up the moisture and
drinks it up; and this gives to the wide stretching sea the savour
of salt. But this cannot be admitted, because if the saltness of the
sea were caused by the heat of the sun, there can be no doubt that
lakes, pools and marshes would be so much the more salt, as their
waters have less motion and are of less depth; but experience shows
us, on the contrary, that these lakes have their waters quite free
from salt. Again it is stated by Pliny in the same chapter that this
saltness might originate, because all the sweet and subtle portions
which the heat attracts easily being taken away, the more bitter and
coarser part will remain, and thus the water on the surface is
fresher than at the bottom [Footnote 22: Compare No. 948.]; but this
is contradicted by the same reason given above, which is, that the
same thing would happen in marshes and other waters, which are dried
up by the heat. Again, it has been said that the saltness of the sea
is the sweat of the earth; to this it may be answered that all the
springs of water which penetrate through the earth, would then be
salt. But the conclusion is, that the saltness of the sea must
proceed from the many springs of water which, as they penetrate into
the earth, find mines of salt and these they dissolve in part, and
carry with them to the ocean and the other seas, whence the clouds,
the begetters of rivers, never carry it up. And the sea would be
salter in our times than ever it was at any time; and if the
adversary were to say that in infinite time the sea would dry up or