CHAPTER II¶
On the Distance from the Profile to the Nape (Cotozzo) of the Said Head, on the Proportions of the Eye and Ear, and on the Painter’s Perspective Net (Rete).
Having explained the vertical divisions of the facial profile \(mk\), we now set forth the horizontal divisions across the width of the head from the front profile \(mk\) to the nape (cotozzo) \(a\), the proportions of the eye, ear, neck, occiput, and crown, and the instrument called the net (la rete) used by painters.
Horizontal Grid Subdivisions and the Painter’s Perspective Net (La Rete)
Just as we divided the vertical height \(mk\) of the oblong rectangle \(kmsb\) into three equal parts, so we divide its horizontal width \(ms\) (and \(kb\)) into three equal parts: \(mo\), \(oq\), and \(qs\) (each equal to \(\frac{1}{3}ms\)).
Bisecting each of these thirds at points \(n, p, r\) divides the width \(ms\) into sixths (\(\frac{1}{6}ms\)); bisecting again gives twelfths (\(\frac{1}{12}ms\)), and bisecting once more gives twenty-fourths (\(\frac{1}{24}ms\)), and so on as finely as we please.
The Painter’s Perspective Net (*La Rete*): The more subdivisions are marked, the easier it is for the perspectivist (prospectivo) to apprehend with his eye the exact proportions of whatever object he wishes to draw—whether a human head, animals, trees, or buildings. For this purpose painters construct a rectangular frame (quadro ouer tetragono longo) strung across in both directions with many fine threads of lute-string, silk, or sinew (molti sottili fili tirati de citera o seta o nervi), forming a grid of squares. Fixing this net (rete) firmly upright between himself and the living model or object he intends to portray (which must also remain still in its pose), the painter sits or kneels at a fixed viewpoint (col suo diligente ochio), observes where the contours of the object fall across the horizontal and vertical threads of the net, and transfers those coordinates with his stylus onto a correspondingly squared sheet of paper, panel, or wall, scaling the squares larger or smaller at will and clothing the outlined form with visual grace (gratia visuale).
Proportions of the Eye, Ear, Neck, Occiput, and Vertex
Returning now to the head in our gridded rectangle \(kmsb\) (Folio 0066 and Plate 0137):
The Eye (*L’Ochio*): Including the upper and lower eyelids and eyebrow, its height is one-sixth (\(\frac{1}{6}\)) of the facial profile \(mk\), and its width is likewise one-sixth.
The Ear (*L’Orechia*): Its height is equal to the length of the nose, namely one-third (\(\frac{1}{3}\)) of the profile \(mk\); its width is one-sixth (\(\frac{1}{6}\)) of the width \(ms\) of the rectangle; and it is positioned midway between the nape (\(a\)) and the bridge of the nose along the central perpendicular \(a\), terminating below at the level of the bottom of the nose and the beginning of the cheek.
The Neck (*El Collo*): Its thickness is two-thirds (\(\frac{2}{3}\)) of the width \(ms\) (namely the span \(os\)), aligning at the front with the pit of the throat (nodo dela gola) and top of the chest.
The Occiput (*L’Occiputto / La Cicotola*): The back of the skull projects behind the rectangle’s rear line by two-thirds of one-sixth, that is, by one-ninth (\(\frac{1}{9}\)) of the width \(ms\).
The Crown or Vertex (*El Vertice*): The top of the skull rises above the hairline \(ms\) by one-sixth (\(\frac{1}{6}\)) of the width \(ms\), reaching its highest point at the midpoint \(p\) and curving down proportionally toward the front (\(o, n, m\)) and toward the back (\(q, r, s\)) with that same irrational visual grace described above.