The Notebooks of Leonardo Da Vinci (67 page)

960.

In the West, near to Flanders, the sea rises and decreases every 6
hours about 20 braccia, and 22 when the moon is in its favour; but
20 braccia is the general rule, and this rule, as it is evident,
cannot have the moon for its cause. This variation in the increase
and decrease of the sea every 6 hours may arise from the damming up
of the waters, which are poured into the Mediterranean by the
quantity of rivers from Africa, Asia and Europe, which flow into
that sea, and the waters which are given to it by those rivers; it
pours them to the ocean through the straits of Gibraltar, between
Abila and Calpe [Footnote 5:
Abila
, Lat.
Abyla
, Gr. , now
Sierra
Ximiera
near Ceuta;
Calpe
, Lat.
Calpe
. Gr., now
Gibraltar. Leonardo here uses the ancient names of the rocks, which
were known as the Pillars of Hercules.]. That ocean extends to the
island of England and others farther North, and it becomes dammed up
and kept high in various gulfs. These, being seas of which the
surface is remote from the centre of the earth, have acquired a
weight, which as it is greater than the force of the incoming waters
which cause it, gives this water an impetus in the contrary
direction to that in which it came and it is borne back to meet the
waters coming out of the straits; and this it does most against the
straits of Gibraltar; these, so long as this goes on, remain dammed
up and all the water which is poured out meanwhile by the
aforementioned rivers, is pent up [in the Mediterranean]; and this
might be assigned as the cause of its flow and ebb, as is shown in
the 21st of the 4th of my theory.

Theory of the circulation of the waters (961. 962).

961.

Very large rivers flow under ground.

962.

This is meant to represent the earth cut through in the middle,
showing the depths of the sea and of the earth; the waters start
from the bottom of the seas, and ramifying through the earth they
rise to the summits of the mountains, flowing back by the rivers and
returning to the sea.

Observations in support of the hypothesis (963-969).

963.

The waters circulate with constant motion from the utmost depths of
the sea to the highest summits of the mountains, not obeying the
nature of heavy matter; and in this case it acts as does the blood
of animals which is always moving from the sea of the heart and
flows to the top of their heads; and here it is that veins burst—as
one may see when a vein bursts in the nose, that all the blood from
below rises to the level of the burst vein. When the water rushes
out of a burst vein in the earth it obeys the nature of other things
heavier than the air, whence it always seeks the lowest places. [7]
These waters traverse the body of the earth with infinite
ramifications.

[Footnote: The greater part of this passage has been given as No.
849 in the section on Anatomy.]

964.

The same cause which stirs the humours in every species of animal
body and by which every injury is repaired, also moves the waters
from the utmost depth of the sea to the greatest heights.

965.

It is the property of water that it constitutes the vital human of
this arid earth; and the cause which moves it through its ramified
veins, against the natural course of heavy matters, is the same
property which moves the humours in every species of animal body.
But that which crowns our wonder in contemplating it is, that it
rises from the utmost depths of the sea to the highest tops of the
mountains, and flowing from the opened veins returns to the low
seas; then once more, and with extreme swiftness, it mounts again
and returns by the same descent, thus rising from the inside to the
outside, and going round from the lowest to the highest, from whence
it rushes down in a natural course. Thus by these two movements
combined in a constant circulation, it travels through the veins of
the earth.

966.

The water of the ocean cannot make its way from the bases to the
tops of the mountains which bound it, but only so much rises as the
dryness of the mountain attracts. And if, on the contrary, the rain,
which penetrates from the summit of the mountain to the base, which
is the boundary of the sea, descends and softens the slope opposite
to the said mountain and constantly draws the water, like a syphon
[Footnote 11: Cicognola, Syphon. See Vol. I, Pl. XXIV, No. 1.] which
pours through its longest side, it must be this which draws up the
water of the sea; thus if
s n
were the surface of the sea, and the
rain descends from the top of the mountain
a
to
n
on one side,
and on the other sides it descends from
a
to
m
, without a doubt
this would occur after the manner of distilling through felt, or as
happens through the tubes called syphons [Footnote 17: Cicognola,
Syphon. See Vol. I, Pl. XXIV, No. 1.]. And at all times the water
which has softened the mountain, by the great rain which runs down
the two opposite sides, would constantly attract the rain
a n
, on
its longest side together with the water from the sea, if that side
of the mountain
a m
were longer than the other
a n
; but this
cannot be, because no part of the earth which is not submerged by
the ocean can be lower than that ocean.

967.

It is quite evident that the whole surface of the ocean—when there
is no storm—is at an equal distance from the centre of the earth,
and that the tops of the mountains are farther from this centre in
proportion as they rise above the surface of that sea; therefore if
the body of the earth were not like that of man, it would be
impossible that the waters of the sea—being so much lower than the
mountains—could by their nature rise up to the summits of these
mountains. Hence it is to be believed that the same cause which
keeps the blood at the top of the head in man keeps the water at the
summits of the mountains.

[Footnote: This conception of the rising of the blood, which has
given rise to the comparison, was recognised as erroneous by
Leonardo himself at a later period. It must be remembered that the
MS. A, from which these passages are taken, was written about twenty
years earlier than the MS. Leic. (Nos. 963 and 849) and twenty-five
years before the MS. W. An. IV.

There is, in the original a sketch with No. 968 which is not
reproduced. It represents a hill of the same shape as that shown at
No. 982. There are veins, or branched streams, on the side of the
hill, like those on the skull Pl. CVIII, No. 4]

968.

I say that just as the natural heat of the blood in the veins keeps
it in the head of man,—for when the man is dead the cold blood
sinks to the lower parts—and when the sun is hot on the head of a
man the blood increases and rises so much, with other humours, that
by pressure in the veins pains in the head are often caused; in the
same way veins ramify through the body of the earth, and by the
natural heat which is distributed throughout the containing body,
the water is raised through the veins to the tops of mountains. And
this water, which passes through a closed conduit inside the body of
the mountain like a dead thing, cannot come forth from its low place
unless it is warmed by the vital heat of the spring time. Again, the
heat of the element of fire and, by day, the heat of the sun, have
power to draw forth the moisture of the low parts of the mountains
and to draw them up, in the same way as it draws the clouds and
collects their moisture from the bed of the sea.

969.

That many springs of salt water are found at great distances from
the sea; this might happen because such springs pass through some
mine of salt, like that in Hungary where salt is hewn out of vast
caverns, just as stone is hewn.

[Footnote: The great mine of Wieliczka in Galicia, out of which a
million cwt. of rock-salt are annually dug out, extends for 3000
metres from West to East, and 1150 metres from North to South.]

On the way in which the sources of rivers are fed.

970.

The body of the earth, like the bodies of animals, is intersected
with ramifications of waters which are all in connection and are
constituted to give nutriment and life to the earth and to its
creatures. These come from the depth of the sea and, after many
revolutions, have to return to it by the rivers created by the
bursting of these springs; and if you chose to say that the rains of
the winter or the melting of the snows in summer were the cause of
the birth of rivers, I could mention the rivers which originate in
the torrid countries of Africa, where it never rains—and still less
snows—because the intense heat always melts into air all the clouds
which are borne thither by the winds. And if you chose to say that
such rivers, as increase in July and August, come from the snows
which melt in May and June from the sun's approach to the snows on
the mountains of Scythia [Footnote 9: Scythia means here, as in
Ancient Geography, the whole of the Northern part of Asia as far as
India.], and that such meltings come down into certain valleys and
form lakes, into which they enter by springs and subterranean caves
to issue forth again at the sources of the Nile, this is false;
because Scythia is lower than the sources of the Nile, and, besides,
Scythia is only 400 miles from the Black sea and the sources of the
Nile are 3000 miles distant from the sea of Egypt into which its
waters flow.

The tide in estuaries.

971.

[3] If two rivers meet together to form a straight line, and then
below two right angles take their course together, the flow and ebb
will happen now in one river and now in the other above their
confluence, and principally if the outlet for their united volume is
no swifter than when they were separate. Here occur 4 instances.

[Footnote: The first two lines of this passage have already been
given as No. 957. In the margin, near line 3 of this passage, the
text given as No. 919 is written.]

On the alterations, caused in the courses of rivers by their
confluence (972-974).

972.

When a smaller river pours its waters into a larger one, and that
larger one flows from the opposite direction, the course of the
smaller river will bend up against the approach of the larger river;
and this happens because, when the larger river fills up all its bed
with water, it makes an eddy in front of the mouth of the other
river, and so carries the water poured in by the smaller river with
its own. When the smaller river pours its waters into the larger
one, which runs across the current at the mouth of the smaller
river, its waters will bend with the downward movement of the larger
river. [Footnote: In the original sketches the word
Arno
is
written at the spot here marked
A
, at
R. Rifredi
, and at
M.
Mugnone
.]

973.

When the fulness of rivers is diminished, then the acute angles
formed at the junction of their branches become shorter at the sides
and wider at the point; like the current
a n
and the current
d
n
, which unite in
n
when the river is at its greatest fulness. I
say, that when it is in this condition if, before the fullest time,
d n
was lower than
a n
, at the time of fulness
d n
will be
full of sand and mud. When the water
d n
falls, it will carry away
the mud and remain with a lower bottom, and the channel
a n
finding itself the higher, will fling its waters into the lower,
d
n
, and will wash away all the point of the sand-spit
b n c
, and
thus the angle
a c d
will remain larger than the angle
a n d
and
the sides shorter, as I said before.

[Footnote: Above the first sketch we find, in the original, this
note: "
Sopra il pote rubaconte alla torricella
"; and by the
second, which represents a pier of a bridge, "
Sotto l'ospedal del
ceppo.
"]

974.

In proportion as the current of the water given forth by the
draining of the lake is slow or rapid in the dry river bed, so will
this river be wider or narrower, or shallower or deeper in one place
than another, according to this proposition: the flow and ebb of the
sea which enters the Mediterranean from the ocean, and of the rivers
which meet and struggle with it, will raise their waters more or
less in proportion as the sea is wider or narrower.

[Footnote: In the margin is a sketch of a river which winds so as to
form islands.]

Whirlpools.

975.

Whirlpools, that is to say caverns; that is to say places left by
precipitated waters.

On the alterations in the channels of rivers.

976.

The subterranean channels of waters, like those which exist between
the air and the earth, are those which unceasingly wear away and
deepen the beds of their currents.

The origin of the sand in rivers (977. 978).

977.

A river that flows from mountains deposits a great quantity of large
stones in its bed, which still have some of their angles and sides,
and in the course of its flow it carries down smaller stones with
the angles more worn; that is to say the large stones become
smaller. And farther on it deposits coarse gravel and then smaller,
and as it proceeds this becomes coarse sand and then finer, and
going on thus the water, turbid with sand and gravel, joins the sea;
and the sand settles on the sea-shores, being cast up by the salt
waves; and there results the sand of so fine a nature as to seem
almost like water, and it will not stop on the shores of the sea but
returns by reason of its lightness, because it was originally formed
of rotten leaves and other very light things. Still, being
almost—as was said—of the nature of water itself, it afterwards,
when the weather is calm, settles and becomes solid at the bottom of
the sea, where by its fineness it becomes compact and by its
smoothness resists the waves which glide over it; and in this shells
are found; and this is white earth, fit for pottery.