_a b_ goes 4 times into _a c_ and 9 into _a m_. The greatest
thickness of the arm between the elbow and the hand goes 6 times
into _a m_ and is equal to _r f_. The greatest thickness of the arm
between the shoulder and the elbow goes 4 times into _c m_, and is
equal to _h n g_. The smallest thickness of the arm above the elbow
_x y_ is not the base of a square, but is equal to half the space
_h_ 3 which is found between the inner joint of the arm and the
wrist joint.

[11]The width of the wrist goes 12 times into the whole arm; that is
from the tip of the fingers to the shoulder joint; that is 3 times
into the hand and 9 into the arm.

The arm when bent is 4 heads.

The arm from the shoulder to the elbow in bending increases in
length, that is in the length from the shoulder to the elbow, and
this increase is equal to the thickness of the arm at the wrist when
seen in profile. And the space between the bottom of the chin and
the parting of the lips, is equal to the thickness of the 2 middle
fingers, and to the width of the mouth and to the space between the
roots of the hair on the forehead and the top of the head [Footnote:
_Queste cose_. This passage seems to have been written on purpose to
rectify the foregoing lines. The error is explained by the
accompanying sketch of the bones of the arm.]. All these distances
are equal to each other, but they are not equal to the
above-mentioned increase in the arm.

The arm between the elbow and wrist never increases by being bent or
extended.

The arm, from the shoulder to the inner joint when extended.

When the arm is extended, _p n_ is equal to _n a_. And when it is
bent _n a_ diminishes 1/6 of its length and _p n_ does the same. The
outer elbow joint increases 1/7 when bent; and thus by being bent it
increases to the length of 2 heads. And on the inner side, by
bending, it is found that whereas the arm from where it joins the
side to the wrist, was 2 heads and a half, in bending it loses the
half head and measures only two: one from the [shoulder] joint to
the end [by the elbow], and the other to the hand.

The arm when folded will measure 2 faces up to the shoulder from the
elbow and 2 from the elbow to the insertion of the four fingers on
the palm of the hand. The length from the base of the fingers to the
elbow never alters in any position of the arm.

If the arm is extended it decreases by 1/3 of the length between _b_
and _h_; and if--being extended--it is bent, it will increase the
half of _o e_. [Footnote 59-61: The figure sketched in the margin is
however drawn to different proportions.] The length from the
shoulder to the elbow is the same as from the base of the thumb,
inside, to the elbow _a b c_.

[Footnote 62-64: The arm sketch on the margin of the MS. is
identically the same as that given below on Pl. XX which may
therefore be referred to in this place. In line 62 we read therefore
_z c_ for _m n_.] The smallest thickness of the arm in profile _z c_
goes 6 times between the knuckles of the hand and the dimple of the
elbow when extended and 14 times in the whole arm and 42 in the
whole man [64]. The greatest thickness of the arm in profile is
equal to the greatest thickness of the arm in front; but the first
is placed at a third of the arm from the shoulder joint to the elbow
and the other at a third from the elbow towards the hand.

[Footnote: Compare Pl. XVII. Lines 1-10 and 11-15 are written in two
columns below the extended arm, and at the tips of the fingers we
find the words: _fine d'unghie_ (ends of the nails). Part of the
text--lines 22 to 25--is visible by the side of the sketches on Pl.
XXXV, No. 1.]