The text provides instructions on how to draw a portrait with a focus on achieving the correct proportions and perspective for an 'oblique' view. It outlines using an oval divided by diameters to set reference points for facial features like the chin and nose, explaining measurements needed for an accurate perspective. Additionally, the text mentions maintaining consistent proportions regardless of the viewing angle.
Artistic Portraiture.
Fourth Example, depicting the Portraiture called "Oblique."
Let, as before, A B C D be the Oval, divided by two Diameters; And suppose that in this, just as in the frontal plane of the Portraiture, the division of the four major Parts, namely the Upper-Head, Forehead, Nose, and the lower part of the Mouth and Chin is the same. Set below at the height of the Chin, the point of incidence or oblique view falls; And draw from this an Oval Arc through the point H in A. which point H. can be found thus; Extend the dotted line G B (for example, in such a case that a Portraiture is halfway between frontal and completely sideways, approximately halfway oblique.) to the side of B, so much that it is equal to G A, and places half of G B, from B in H, and you have there the point where the said Arc must intersect the Horizontal B D. And this Arc is the elevation of the Oval, or if you wish, the Lateral Aspect of the Oval. The elevation of the Nose should extend a third of its Length beyond this Arc; as indicated clearly beside here. Where one also sees that the Chin and width of the oblique Eye, through the chance Stroke of the Oval at the side, are determined, and the other side is as wide as in the frontal Plane Portraiture, of which G. is here the Mid-point. In the height of the Parts, there is no difference, because this is neither under the Natural, that is Horizontal.
Translation Notes:
1. "Tronie" refers to a style of portraiture or facial depiction, and "geweken" indicates an oblique or side-turned position.
2. "Kinne" is an old term for chin.
3. Terms like "Toevallig punkt des omsiens" refer to incidental or random viewing points, important in perspective drawing.