The neck is cylindrical in shape and follows the curve of the spinal column. Even when the head is thrown back the neck curves slightly forward. From ln-hind each ear a muscle descends inward to the root of the neck. These muscles almost meet each other, making a point at the pit; they form the sides of an inverted triangle whose base is the canopy of the chin. The neck has the following action: up and down, from side to side and rotary.
The thorax or chest is composed of bones and cartilage. It is designed to protect the heart and lungs, much in the way a baseball mask protects the face, and to permit turning and twisting of the body. The pelvis is the mechanical axis of the body. It is the fulcrum of trunk and legs, and is large in proportion. Its mass is inclined a little forward. Compared with the trunk above it is somewhat square. The abdominal arch, formed by the false ribs going outward and downward from the end of the breastbone, separates the abdomen from the thorax.
1. STERHO-CLEIDO MASTOID 2 TRAPEZIUS
The arm has its base in the shoulder girdle. The forearm is rounded or oval, depending upon whether the bones of the forearm are crossed. The wrist is twice as wide as it is thick. The accompanying sketches give you a general idea of the construction of the arm, both front and rear views.
The bones of the hand are blended with those of the wrist, making one mass, the hand moving with the wrist. The width of the wrist diminishes where it joins the arm. The hand has two masses: that of the hand proper and that of the thumb. The back of the hand is nearly flat except in the clenched fist. The tendons of the long extensors are superficial and may be raised sharply under the skin.
The bones of the finger are narrower in the shaft than at either end. The joints are square, the tips triangular. The middle joint of each finger is the largest. In the back view, the fingers as a whole arch toward the middle finger. In the profile view, there is a stepdown from each segment to the one beyond, bridged by a wedge.
The thigh bone ends at the knee as a hinge joint. The leg requires only a backward and forward movement for which a hinge is sufficient. The column of the thigh and leg diminishes in thickness as it descends to the foot. From any view it also has a reverse curve that extends its length. The leg at the calf is triangular, at the ankle it is square. From the back, the hips and buttocks are square and overhang the pillars of the thighs. The thigh is rounded in from half way down to the knee, and then it it becomes square to just below the knee. The calf of the leg is triangular, the ankle square.
Think of the knee as a square with sides beveled forward, slightly hollowed in back and carrying the knee cap in front. When the knee is straight, a bulge forms on either side exactly opposite the joint itself. The back of the knee, when bent, is hollowed by the hamstring tendons on either side. When straight, the bone becomes prominent between them, making, with these tendons, the knobs. The inside of the knee is larger, and the knee as a whole is bent convex toward its fellow. The hip socket, the knee and ankle are all in line when the leg is straight.
The foot is arched, buttressed at either end by heel and toe. The keystone of the arch moves freely between the bones of the leg.
All we need to know about perspective is the simple fact that things look smaller as they get further away from the eye. When you see a column of soldiers at attention, the nearest soldier looks tallest; down the line each man seems to dwindle in size until the last one may be a mere speck. The size of the image bears a relation to the distance of the object from the eye. While we do not need to know the mathematics involved, this is the first important law of practical perspective. In the case of the upright candle, we have a very simple image, with all parts of the object an equal distance from the eye (fig. 236). Suppose the candle falls over backward so that its length is no longer parallel to your eye. Things immediately begin to happen to the shape of your image because different parts of it are now different distances away from you. Just as distance affects the size of any whole image, it plays tricks with the shape of the object when the object's parts are unequal distances away. Examples of this may be seen in everyday photography (fig. 237). Everyone is familiar also with the phenomenon of the railroad tracks as they appear to converge on the horizon (fig. 238).
Thus we see that perspective is simply judging the correct relation of one part to another. As you draw, you can train your eye to do this, but the following rules and simple measuring devices will help you at the start.
If you are looking down a street, you will notice that the retreating lines of all regularly shaped objects converge at a single vanishing point if you extend them far enough (fig. 239). This vanishing point. (VP) is on the horizon line. While there may be no actual horizon visible, this is simply an arbitrary, horizontal line marking the eye level of the spectator. Surfaces which are parallel to the horizon line, such as the near side of the building at the left, will of course be drawn in their normal shapes, since all parts of them are approximately equidistant from your eye.
Now if you move so that you are looking at the corner of a rectangular form, you find that the projected lines of its right side converge at a point somewhere on the right hand portion of the horizon line, while the lines of its left side have their own vanishing point at the left (fig. 240).
This is two-point perspective, the commonest variety. If you move your eye level up or down, the horizon line moves accordingly and the perspective changes. As an example, if you lie on the ground all lines converge downward (fig. 241).
If your vantage point is high, the opposite will take place (fig. 242).
How to Measure Figures at Varying Distances
A simple method of determining the correct height of several figures in relation to each other is the following (fig. 243) : One, establish the horizon line of your picture and draw your first figure at whatever place and height you wish. Two, mark with a dot, A. the spot you select for your second figure.
Three, run a line from the fect of your first figure through A until it intersects the horizon. This is your vanishing point (VP), lour, draw a line from VP back to the head of your first figure. Your second figure should measure the distance between the two lines at A. The whole study of perspective is fascinating and full of surprises for the student. Once the normal kind of perspective is understood, you can investigate the freakish kinds caused by close-ups, height, depths, curves, and other unusual angles.