The text describes the method for dividing the head's proportions when viewed from the front, focusing on places of key facial features like the mouth and eyes. The guide uses specific measurements, with the head divided into four equal parts vertically and provides proportional details for features like the mouth and nose. It includes technical instructions on drawing these features accurately, emphasizing the importance of straight lines and proportions in achieving a true representation.
Proportion of the Head Viewed from the Front.
1° Head Viewed from Front and Right.
After finding the mass of the head, as seen in plate 10, fig. 6 (page 64), the head is divided, and the placement of the organs is determined as follows:
In a head viewed from the front, the broadest width, taken above the eyebrows, is equal to three-quarters of the height; here, plate 14, fig. 1, EF is equal to three-quarters of CD or AB. From point B, the upper end of the main line of operation, draw a line at a right angle from right to left. From point A, the lower end, draw a second line parallel to the first. Between these two lines, draw a vertical line which serves as a scale of proportions for the entire head.
The height of the head viewed from the front is divided, like the head seen in profile, into four equal parts. The vertical line represented by CD is divided into four equal parts. From the division points marked 1, 2, 3, lines parallel to line CB are drawn, extending to meet the main line AB, allowing the head to be divided into four equal sections.
The mouth is placed at the small third, and sometimes at the exact third of the distance from the nose to the chin. The point E on line CD, or point a on line AB, determines the mouth's opening. The width of the mouth is equal to two-thirds of the distance from the nose to the chin: here fc, equals two-thirds of Ab. As previously stated, the divisions can be found on the main line without using the scale. From division points abcd, lines that should form a right angle with the line AB are drawn. These lines are straight and parallel to each other.
Just as in the head viewed in profile, the width of the nose is equal to half its height: thus, a dimension represented here by Fg, equal to half the height bc, or half the second part represented here by 1 and 2, is taken. This width of the nose should be marked halfway on either side of the main line AB.
The eyes are placed on a line parallel to the other operational lines: this line must be below the attachment of the nose, and should pass through the two corners of the eyes called the internal angle, or caruncle lacrymale represented here by op, and by the two corners of the eyes forming the external angle,
Strictly speaking, there should be only one of these lines that appears straight, and it is the line found at the height of the observer's eye: those that are higher or lower become curved; however, this curve is very slight, and this slight difference does little to confuse students. Thus, we assume them to be straight lines, with the head itself being straight.