311.

The distance from the attachment of one ear to the other is equal to that from the meeting of the eyebrows to the chin, and in a fine face the width of the mouth is equal to the length from the parting of the lips to the bottom of the chin.

312.

The cut or depression below the lower lip of the mouth is half way between the bottom of the nose and the bottom of the chin.

The face forms a square in itself; that is its width is from the outer corner of one eye to the other, and its height is from the very top of the nose to the bottom of the lower lip of the mouth; then what remains above and below this square amounts to the height of such another square, a b is equal to the space between c d; d n in the same way to n c, and likewise s r, q p, h k are equal to each other.

It is as far between m and s as from the bottom of the nose to the chin.  The ear is exactly as long as the nose.  It is as far from x to j as from the nose to the chin.  The parting of the mouth seen in profile slopes to the angle of the jaw.  The ear should be as high as from the bottom of the nose to the top of the eye-lid.  The space between the eyes is equal to the width of an eye.  The ear is over the middle of the neck, when seen in profile.  The distance from 4 to 5 is equal to that from s_ to r.

[Footnote:  See Pl.  VIII, No.  I, where the text of lines 3-13 is also given in facsimile.]

313.

(a b) is equal to (c d).

[Footnote:  See Pl.  VII, No. 3.  Reference may also be made here to two pen and ink drawings of heads in profile with figured measurements, of which there is no description in the MS. These are given on Pl.  XVII, No. 2.—­A head, to the left, with part of the torso [W.  P. 5a], No. 1 on the same plate is from MS. A 2b and in the original occurs on a page with wholly irrelevant text on matters of natural history.  M. RAVAISSON in his edition of the Paris MS. A has reproduced this head and discussed it fully [note on page 12]; he has however somewhat altered the original measurements.  The complicated calculations which M. RAVAISSON has given appear to me in no way justified.  The sketch, as we see it, can hardly have been intended for any thing more than an experimental attempt to ascertain relative proportions.  We do not find that Leonardo made use of circular lines in any other study of the proportions of the human head.  At the same time we see that the proportions of this sketch are not in accordance with the rules which he usually observed (see for instance No. 310).]

The head a f 1/6 larger than n f.

315.

From the eyebrow to the junction of the lip with the chin, and the angle of the jaw and the upper angle where the ear joins the temple will be a perfect square.  And each side by itself is half the head.