Notes and Sketches on the Anatomy of the Horse, Vol. 2

Transcribed from Leonardo's mirror script into normal left-to-right English.

Why the sun has no rays original: "perchè 'l sole non à razi". Leonardo is likely exploring the physical nature of light versus the visual phenomenon of "rays" seen by the eye.

Top right block: Optical study of perspective from the Sun and Earth

If the eye were in the center of the sun,
it would see all its planets
without any shadow. And it would
also see its planets without
the striking of one ray term: razo (ray). Leonardo uses this to describe the linear path of light. against
another ray. And if it were in the center of the
earth, it would see those same rays
all as perpendicular rays;
because the rays that depart from the sun
and pass through the center of the earth
form a single ray among themselves.
And if we were between the sun
and the earth, we would see
oblique rays—extremely oblique—
because a ray is more oblique
the further the eye is removed
from the center of the earth.

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Middle left block: Study of the apparent size of the sun's reflection

Whether it is possible that the
sun might appear larger in one
eye than in the other of the
same body. Because
if the sun struck the
surface of the eye
with angles of three types—
namely oblique, acute, and right—
and the oblique is larger
than the acute, and the right
is the largest of all.

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Middle block: Analogy between water and hair

Note how water, in its
motion, creates such a
diversity of movements
in any given space.
Because as the water moves,
one part of it is faster
than the other, and thus
diverse revolutions term: revoluzioni (revolutions/eddies). Refers to the swirling, circular motions of a fluid. are generated.
And this also happens
in the manes of horses,
which resemble
water; one part of it
moves due to the weight of the hair,
and part due to its
curling, just as
water does.

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Text to the right of the horse's head study

Observe the motion of the surface term: vello dell'acqua (fleece/surface of the water). A poetic term Leonardo uses to describe the "skin" or top layer of moving water. of the
water, which acts like
hair, which has two motions:
one of which follows the weight
of the fleece, the other the line of
its revolving. Thus water
has its circular revolutions,
of which one follows the
principal motion, the other follows
the incident and reflected motion.

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Numerical calculations and geometric annotations at bottom

1000
500
250
125

1 2

• -
  0 0

8 4

• -
  4 2