All the leaves which hung towards the earth by the bending of the
shoots with their branches, are turned up side down by the gusts of
wind, and here their perspective is reversed; for, if the tree is
between you and the quarter of the wind, the leaves which are
towards you remain in their natural aspect, while those on the
opposite side which ought to have their points in a contrary
direction have, by being turned over, their points turned towards
you.
472.
Trees struck by the force of the wind bend to the side towards which
the wind is blowing; and the wind being past they bend in the
contrary direction, that is in reverse motion.
473.
That portion of a tree which is farthest from the force which
strikes it is the most injured by the blow because it bears most
strain; thus nature has foreseen this case by thickening them in
that part where they can be most hurt; and most in such trees as
grow to great heights, as pines and the like. [Footnote: Compare the
sketch drawn with a pen and washed with Indian ink on Pl. XL, No. 1.
In the Vatican copy we find, under a section entitled '_del fumo_',
the following remark: _Era sotto di questo capitulo un rompimento di
montagna, per dentro delle quali roture scherzaua fiame di fuoco,
disegnate di penna et ombrate d'acquarella, da uedere cosa mirabile
et uiua (Ed. MANZI, p. 235. Ed. LUDWIG, Vol. I, 460). This appears
to refer to the left hand portion of the drawing here given from the
Windsor collection, and from this it must be inferred, that the leaf
as it now exists in the library of the Queen of England, was already
separated from the original MS. at the time when the Vatican copy
was made.]
Light and shade on clouds (474-477).
474.
Describe how the clouds are formed and how they dissolve, and what
cause raises vapour.
475.
The shadows in clouds are lighter in proportion as they are nearer
to the horizon.
[Footnote: The drawing belonging to this was in black chalk and is
totally effaced.]
476.
When clouds come between the sun and the eye all the upper edges of
their round forms are light, and towards the middle they are dark,
and this happens because towards the top these edges have the sun
above them while you are below them; and the same thing happens with
the position of the branches of trees; and again the clouds, like
the trees, being somewhat transparent, are lighted up in part, and
at the edges they show thinner.
But, when the eye is between the cloud and the sun, the cloud has
the contrary effect to the former, for the edges of its mass are
dark and it is light towards the middle; and this happens because
you see the same side as faces the sun, and because the edges have
some transparency and reveal to the eye that portion which is hidden
beyond them, and which, as it does not catch the sunlight like that
portion turned towards it, is necessarily somewhat darker. Again, it
may be that you see the details of these rounded masses from the
lower side, while the sun shines on the upper side and as they are
not so situated as to reflect the light of the sun, as in the first
instance they remain dark.
The black clouds which are often seen higher up than those which are
illuminated by the sun are shaded by other clouds, lying between
them and the sun.
Again, the rounded forms of the clouds that face the sun, show their
edges dark because they lie against the light background; and to see
that this is true, you may look at the top of any cloud that is
wholly light because it lies against the blue of the atmosphere,
which is darker than the cloud.
[Footnote: A drawing in red chalk from the Windsor collection (see
Pl. XXIX), representing a landscape with storm-clouds, may serve to
illustrate this section as well as the following one.]
477.
OF CLOUDS, SMOKE AND DUST AND THE FLAMES OF A FURNACE OR OF A
BURNING KILN.
The clouds do not show their rounded forms excepting on the sides
which face the sun; on the others the roundness is imperceptible
because they are in the shade. [Footnote: The text of this chapter
is given in facsimile on Pls. XXXVI and XXXVII. The two halves of
the leaf form but one in the original. On the margin close to lines
4 and 5 is the note: _rossore d'aria inverso l'orizonte_--(of the
redness of the atmosphere near the horizon). The sketches on the
lower portion of the page will be spoken of in No. 668.]
If the sun is in the East and the clouds in the West, the eye placed
between the sun and the clouds sees the edges of the rounded forms
composing these clouds as dark, and the portions which are
surrounded by this dark [edge] are light. And this occurs because
the edges of the rounded forms of these clouds are turned towards
the upper or lateral sky, which is reflected in them.
Both the cloud and the tree display no roundness at all on their
shaded side.
On images reflected in water.
478.
Painters often deceive themselves, by representing water in which
they make the water reflect the objects seen by the man. But the
water reflects the object from one side and the man sees it from the
other; and it often happens that the painter sees an object from
below, and thus one and the same object is seen from hind part
before and upside down, because the water shows the image of the
object in one way, and the eye sees it in another.
Of rainbows and rain (479. 480).
479.
The colours in the middle of the rainbow mingle together.
The bow in itself is not in the rain nor in the eye that sees it;
though it is generated by the rain, the sun, and the eye. The
rainbow is always seen by the eye that is between the rain and the
body of the sun; hence if the sun is in the East and the rain is in
the West it will appear on the rain in the West.
480.
When the air is condensed into rain it would produce a vacuum if the
rest of the air did not prevent this by filling its place, as it
does with a violent rush; and this is the wind which rises in the
summer time, accompanied by heavy rain.
Of flower seeds.
481.
All the flowers which turn towards the sun perfect their seeds; but
not the others; that is to say those which get only the reflection
of the sun.