The plane of the forehead slopes upward and backward to become the cranium; and the sides turn sharply to the plane of the temples.
The plane of the face, divided by the nose, is broken on each side by a line from the outer corner of the cheek bone to the center of the upper lip, making two smaller planes.
The outer of these turns to become the plane of the jaw, which also is again divided by a line marking the edge of the masseter muscle, running from the outer border of the cheek bone to the corner of the jaw; and again making two secondary planes, one toward the cheek and one toward the ear.
The relations of these masses and planes is to the moulding of a head what architecture is to a house. They vary in proportion with each individual, and must be carefully compared with a mental standard.
In profile the masses of the head are the same -the cranium, the skeleton of the face, and the jaw.
The front border of the temple is seen to be a long curve, almost parallel to the curve of the cranium.
The top of the cheek bone is seen to be prolonged backward toward the ear as a ridge (zygoma or yoke) which also marks the base of the temple. It slopes slightly down in front.
From cheek bone and zygoma, where they meet, a lesser ridge is seen rising between the temple and the orbit, marking the back of the orbit and the first part of the long line of the temple.
The planes and divisions of planes of the face are the same as in the front view, in different perspective.
The upper part of the eye socket or orbit is marked by the brow, whose bristles are so placed as to divert moisture and dirt outward away from the lid and eye.
Below it on the lid are three planes, wedging into each other at different angles. The first is from the bridge of the nose to the eye. The second is from the brow to the cheek bone; which is again divided into two smaller planes, one sloping toward the root of the nose, the other directed toward and joining with the cheek bone.
The lower lid is quite stable. It is the upper lid that moves. When the eye is closed, its curtain is drawn smooth; when opened, its lower part follows the curve of the eyeball straight back, folding in beneath the upper part as it does so, and leaving a wrinkle to mark the fold.
The lower lid may be wrinkled and slightly lifted inward, bulging below the inner end of the lid.
The transparent cornea or "apple" of the eye is raised perceptibly, and is always curtained by the upper lid, in part, so that it always makes a slight bulge in the lid, whatever the position, and whether open or closed. The eyeball has about half a right angle of movement in two planes.
At the inner corner of the lids is a narrow pit (canthus), floored by a pinkish membrane, which projects some distance beyond the walls of the pit when the eye is turned far out. At the corners of the pit are the openings of the tear ducts, which drain off the excess of lacrymal (tear) fluid. There is a continuous light secretion of this fluid, which is spread over the eyeball by the constant winking of the upper lid. The thin film of liquid thus kept there reflects light perfectly from its surface.
The lashes, projecting from the margin of the lids, serve both as curtains to shade and as delicate feelers to protect the eye.
The immovable masses of the forehead, nose and cheek bones form a strong setting for this most variant and expressive of the features.
In looking at any feature one naturally compares it with his concept of the average of such features, or with some mental standard or ideal.
The variations of such features will then fall into classes which represent the more usual variations thereof.
Eyebrows may be level or sloping; straight or arched; short or long; narrow or wide, thick, scanty or penciled.
Lids may be thick or thin, although the upper lid is always thicker along its margin, and always protrudes if the eye protrudes, and is raised over the cornea.
Eye sockets may be far apart or near together; long or short; bulging or shallow.
The opening between the lids may be triangular or round, a loop, or a button hole.
The Eye Socket. Wedges, Planes and Their Angles.
The Eye. Angular Opening Between the Lids.