Cross - Light and Shade in Charcoal, Pencil and Brush Drawing

Aesthetics. The science which treats of the beautiful, and its various modes of representation in nature and art ; the philosophy of the fine arts.

Accent. Emphasis of light or of dark in a light and shade drawing; of dark in an outline drawing ; and of color or of light and dark in a color sketch.

Altitude. The perpendicular distance between the bases, or between the vertex and the base, of a solid or plane figure.

Angle. The difference in direction of two lines which meet or tend to meet. The lines are called the sides, and the point of meeting, the vertex of the angle.

An angle is measured by means of an arc of a circle described from its vertex as a center and included between its sides. The center of the arc is the vertex of the angle.

The angle formed by two radii of the circle which include an arc equal to of the circumference is taken as the unit for measuring angles, and is called a degree.

The degree is divided into sixty equal parts called minutes, and the minutes into sixty equal parts called seconds.

Degrees, minutes, and seconds are denoted by symbols. Thus 5 degrees, 13 minutes, 12 seconds, is written 5 13 12.

A RIGHT ANGLE is one which is formed by two radii which include of the circumference. It contains 90. A straiglit angle is equal to two right angles and contains 180.

ACUTE ANGLE. An angle less than a right angle.

OBTUSE ANGLE. An angle greater than a right angle.

OBLIQUE ANGLE. One which is not a right or a straight angle.

Apex. See Vertex. The summit, or highest point of an object.

Apparent Color. The color which any object appears to have.

Appearance. The image produced in the eye by the form, light and shade, or color of any object.

Arc. See Circle.

Arrangement. The orderly disposition of objects or forms.

Atmosphere. The effect of reality due to correct drawing and values artistically rendered.

Axis of a Solid. An imaginary straight line passing through its center and about which the different parts are symmetrically arranged.

Axis of a Figure. A straight line passing through the center of a figure, and dividing it into two equal parts.

Balance. The equality of parts, obtained by the proper distribution of lines or of light and dark.

Base. The opposite parallel polygons of prisms. The polygon opposite the vertex of a pyramid. The plane surfaces of cylinders and cones. The opposite parallel sides of a parallelogram or trapezoid. The shortest or longest side of an isosceles triangle, and any side in any other triangle, but usually the lowest.

Bisect. To divide into two equal parts.

Blend. To soften and bring together.

Blocking-in Lines. The lightest and simplest suggestions of the leading lines and masses of the subject.

Blur Glass. A magnifying glass of about 15 inches focus.

Brightness or Luminosity. The strength of the light sent to the eye by any color. A luminous or bright color sends a large amount of light to the eye.

Broken Color. Color changed by the addition of gray.

Breadth. Simplicity due to large masses which subordinate details to the spirit and effect of the whole.

Cast. An object made of plaster-of-Paris.

Center of Vision. The point on the picture plane directly opposite the station-point.

Chiaro-oscuro. The art of combining light and shade.

Circle. A plane figure bounded by a curved line, called a circumference, all points of which are equally distant from a point within called the center .

The boundary line is called the CIRCUMFERENCE.

DIAMETER. A straight line drawn through the center, and connecting opposite points in the circumference, as a b.

RADIUS. The distance from its center to the circumference, as c e.

SEMICIRCLE. Half a circle, formed by bisecting it with a diameter, as adba.

ARC. Any part of the circumference, as e b.

CHORD. A straight line whose ends are in the circumference, as f g .

SEGMENT. The part of a circle bounded by an arc and a chord, as f h g f.

SECTOR. The part of a circle bounded by two radii and an arc, as b e c b.

QUADRANT. A sector bounded by two radii and one fourth of the circumference, as a c d a .

TANGENT. A straight line which meets a circumference, but being produced does not cut it, as k d. The point of meeting is called the point of contact or point of tangency .

Cold Colors. Those in which blue predominates.

Color. The result of the decomposition of light into the various elements composing it. It is a sensation due to the effects produced upon the eye by the waves of different lengths found in light, and does not exist outside of ourselves. Practically we speak of material color as that which decomposes light, and most objects are colored in the sense that they decompose light and send to the eye rays which are not white. Thus a body which reflects all the rays equally is white; one which absorbs all the rays except the red rays is red; and one which absorbs all the rays except the blue is blue; and one which absorbs practically all the rays is black.

Composition. The arrangement of the different lines, parts, and masses of a subject.

Concave. Curving inwardly.

Cone. A solid bounded by a plane surface called the base, which is a circle, ellipse, or other curved figure, and by a lateral surface which is everywhere curved, and tapers to a point called the vertex . Its base names the cone. Thus a circular cone is one whose base is a circle.

A RIGHT CIRCULAR CONE is generated by an isosceles triangle which revolves about its altitude as an axis. The equal sides of the triangle in any position are called elements of the surface. The length of an element is called the slant height of the cone. Unless otherwise stated, cone means a right circular cone.