Preliminary Terms and Definitions.
Like all the arts, drawing has a nomenclature of its own, and nothing can be more helpful to the beginner than to know the name of things relating to the art of drawing. This is a language almost peculiar to itself, and used daily and hourly by many thousands of superintendents, foremen and master mechanics, as well as by owners, designers and draughtsmen, hence its introduction at this early stage.
ALTITUDE.—This is the elevation of an object above its base, or the perpendicular distance between the top and bottom of a figure.AngleFig. 33.Right angleFig. 34.Acute angleFig. 35.Obtuse angleFig. 36.AnglesFig. 37.ANGLEis the difference in the direction of two lines which meet or tend to meet. The lines are calledthe sidesand the point of meeting, thevertexof the lines.To make an angle apparent, the two lines must meet in a point, asA BandA C, which meet in the pointA, as shown infig. 33.Angles are measured by degrees.ADegreeis one of the three hundred and sixty equal parts of the space about a point in a plane.Angles are distinguished in respect to magnitude by the terms Right, Acute and Obtuse Angles.ARight Angleis that formed by one line meeting another, so as to make equal angles with that other.The lines forming a right angle areperpendicular to each other.AnAcute Angleis less than a right angle. SeeFig. 35.AnObtuse Angleis greater than a right angle. SeeFig. 36.Obtuse and acute angles are also calledoblique angles; and lines which are neither parallel nor perpendicular to each other are calledoblique lines.TheVertexorApexof an angle is the point in which the including lines meet.An angle is commonly designated by a letter at its vertex; but when two or more angles have their vertices at the same point, they cannot be thus distinguished.For example, when the three linesA B,A C, andA Dinfig. 37meet in the common pointA, we designate either of the angles formed, by three letters, placing that at the vertex between those at the opposite extremities of the including lines. Thus, we say, the angleB A C, etc.APEX.—The summit or highest point of an object.ARC.—Seecircle.AXIS OF A SOLID.—An imaginary straight line passing through its center.AXIS OF A FIGURE.—A straight line passing through the center of a figure, and dividing it into two equal parts.BASE.—The base of a solid figure is that on which it stands—the lowest part.BISECT.—To divide into two equal parts.BISECTOR.—A line which bisects.CircleFig. 38.CIRCLE.—ACircleis a plane figure bounded by one uniformly curved line, all of the points in which are at the same distance from a certain point within, called theCenter.TheCircumferenceof a circle is the curved line that bounds it.TheDiameterof a circle is a line passing through its center, and terminating at both ends in the circumference, asA C B.TheRadiusof a circle is a line extending from its center to any point in the circumference. It is one-half of the diameter. All the diameters of a circle are equal, as are also all the radiiC D,C BandC A.AnArcof a circle is any portion of the circumference, asB DandA D.Semi-Circle.—Half a circle formed by bisecting it with a diameter, asA C B.Fig. 38.An angle having its vertex at the center of a circle is measured by the arc intercepted by its sides. Thus, the arcA Dmeasures the angleA C D, and in general, to compare different angles, we have but to compare the arcs, included by their sides, of the equal circles having their centers at the vertices of the angles.CIRCUMSCRIBE.—To draw a line of figures about or outside, such as a circle drawn around a square touching its corners or angles.Inscribe.—To draw a line or figure inside or on the interior, such as a circle drawn within a square touching its sides.CONCAVE.—Curving inwardly.CONE.—A solid body or figure having a circle for its base, and its top terminated in a point or vertex.CONSTRUCTION.—The making of any object.CONTOUR.—The outline of the general appearance of an object.CONVERGENCE.—Lines extending towards a common point.CONVEX.—Rising or swelling into a round form—the opposite to concave.CORNER.—The point of meeting of the edges of a solid, or the two sides of a plane figure.CROSS-HATCHES.—In free-hand drawing the use of lines crossing each other to produce light and shade effects.CURVE.—A line of which no part is straight.Reversed Curve.—One whose curvature is first in one direction and then in the opposite direction.Spiral Curve.—A plain curve which winds about and recedes, according to some law, from its point of beginning, which is called its center.CYLINDER.—A solid bounded by a curved surface and by two opposite faces called bases; the bases may be any curved figures and give the name to the cylinder; thus a circular cylinder is one whose bases are circles.CYLINDRICAL.—Having the general form of a cylinder.DEGREE.—The 360th part of a circle.DESCRIBE.—To make or draw a curved line; to draw a plan.DESIGN.—Any arrangement or combination to produce desired results in industry or art. To delineate a form or figure by drawing the outline—a sketch.DEVELOP.—To unroll or lay out.DIAGONAL.—A right line drawn from angle to angle of a quadrilateral or many angled figure and dividing it into two parts.DIAMETER.—A right line passing through the center of a circle or other round figure terminated by the curve and dividing the figure symmetrically into two equal parts.EDGE.—The intersection of any two surfaces.ELEVATION.—The term elevation, vertical projection andfront view—applied to drawings—all have the same meaning.FACE.—One of the plane surfaces of a solid; it may be bounded by straight or curved edges.FINISHING.—Completing a drawing whose lines have been determined by erasing unnecessary lines and strengthening and accentuating where this is needed.FORESHORTENING.—Apparent decrease in length, owing to objects being viewed obliquely; thus a wheel, when seen obliquely, instead of appearing round, presents the appearance of an ellipse.FREE-HAND.—Executed by the hand unaided by instruments.GENERATED.—Produced by.GEOMETRIC.—According to geometry.HALF-TINT.—The shading produced by means of parallel equidistant lines.HEMISPHERE.—Half a sphere obtained by bisecting a sphere by a plane.HORIZONTAL.—Parallel to the surface of smooth water. In drawing, a line drawn parallel to the top and bottom of the sheet is called horizontal.INSCRIBE.—Seecircumscribe—its opposite.INSTRUMENTAL.—By the use of instruments.LINE.—A line has length, only, as A C; a right line is a straight line, the shortest line that can be drawn between two points, A——C.Straight.One which has the same direction throughout its entire length.Curved.One no part of which is straight.Broken.One composed of different successive straight lines.Mixed.One of straight and curved lines.Center.A line used to indicate the center of an object.Construction.A working line used to obtain required lines.Dotted.A line composed of short dashes.- - - - - -Dash.A line composed of long dashes.— — —DotandDash. A line composed of dots and dashes alternating.— · — · —Dimension.A line upon which a dimension is placed.Full.An unbroken line, usually representing a visible edge.———Shadow.A line about twice as wide as the ordinary full line.A straight line is often called simply a line, and a curved line a curve.LONGITUDINAL.—In the direction of the length of an object.MODEL.—A form used for study.OBLIQUE.—Neither horizontal nor vertical.OBLONG.—A rectangle with unequal sides.OVAL.—A plane figure resembling the longitudinal section of an egg; or elliptical in shape.OVERALL.—The entire length.PARALLEL.—Having the same direction and everywhere equally distant.PATTERN.—That which is used as a guide or copy in making things.Flat.One made of paper or other thin material.Solid.One which reproduces the form and size of the object to be made.PERIMETER.—The boundary of a closed plane figure.PERPENDICULAR.—At an angle of 90°.PERSPECTIVE.—View; drawing objects as they appear to the eye from any given distance and situation, real or imaginary.PLAN.—Plan, horizontal projection andtop viewhave the same meaning.PLANE FIGURE.—A part of a plane surface bounded by straight or curved lines, or by both combined.PolygonFig. 39.POLYGON.—A plane figure bounded by straight lines called the sides of the polygon. The least number of sides that can bound a polygon is three. Polygons bounded by a greater number of sides than four are denominated only by the number of sides.A polygon of five sides is called aPentagon; of six, aHexagon; of seven, aHeptagon; of eight, anOctagon; of nine, aNonagon, etc.Diagonalsof a polygon are lines joining the vertices of angles not adjacent.ThePerimeterof a polygon is its boundary considered as a whole.TheBaseof a polygon is the side upon which the polygon is supposed to stand.TheAltitudeof a polygon is the perpendicular distance between the base and a side or angle opposite the base.ParallelogramFig. 40.AQuadrilateralis a polygon having four sides and four angles.AParallelogramis a quadrilateral which has its opposite sides parallel.The side upon which a parallelogram stands and the opposite side are called respectively its lower and upper bases.ARectangleis a parallelogram having its angles right angles.ASquareis an equilateral rectangle,fig. 41.SquareFig. 41.RhombusFig. 42.TrapeziumFig. 43.TrapezoidFig. 44.PolyhedronsFigs. 45-49.ARhomboidis an oblique-angled parallelogram.ARhombusis an equilateral rhomboid,fig. 42.ATrapeziumis a quadrilateral having no two sides parallel,fig. 43.ATrapezoidis a quadrilateral in which two opposite sides are parallel, and the other two oblique,fig. 44.A POLYHEDRONis a solid bounded by planes. There are five regular solids which are shown infigs. 45, 46, 47, 48 and 49. A regular solid is bounded by similar and regular plane figures.Fig. 45.—Thetetrahedron, bounded by four equilateral triangles.Fig. 46.—Thehexahedron, or cube, bounded by six squares.Fig. 47.—Theoctahedron, bounded by eight equilateral triangles.Fig. 48.—Thedodecahedron, bounded by twelve pentagons.Fig. 49.—Theicosahedron, bounded by twenty equilateral triangles.PRISM.—A solid whose bases or ends are very similar plane figures, and whose sides are parallelograms; prisms are called triangular, square, etc., according as the bases are triangles, squares, etc.PRODUCE.—To continue or extend.PROFILE.—An outline or contour.PROJECTION.—The view of an object obtained upon a plane by projecting lines perpendicular to the plane.QUADRANT.—The fourth part; a quarter; the quarter of a circle.QUADRISECT.—To divide into four equal parts.SECTION.—A projection upon a plane parallel to a cutting plane which intersects any object. The section generally represents the part behind the cutting plane, and represents the cut surfaces by diagonal lines.SECTIONAL.—Showing the section made by a plane.SHADOW.—Shade and shadow have about the same meaning.SOLID.—A solid has three dimensions—length, breadth and thickness.SPHERE.—A solid bounded by a curved surface every point of which is equally distant from a point within called the center.SURFACE.—The boundary of a solid. It has but two dimensions—length and breadth. Surfaces are plane or curved.APlane Surfaceis one upon which a straight line can be drawn in any direction.ACurved Surfaceis one no part of which is plane.The surface of the sphere is curved in every direction, while the curved surfaces of the cylinder and cone are straight in one direction.The surface of a solid is no part of the solid, but is simply the boundary of the solid. It has two dimensions only, and any number of surfaces put together will give no thickness.TriangleFig. 50.TriangleFig. 51.TriangleFig. 52.TriangleFig. 53.TriangleFig. 54.SYMMETRY.—Design.A proper adjustment or adaptation of parts to one another and to the whole.TRISECT.—To divide into three equal parts.TRIANGLE.—A triangle is a polygon having three sides and three angles.Triis a Latin prefix signifying three; hence a Triangle is literally a figure containing three angles.AScalene Triangleis one in which no two sides are equal. Seefig. 50.AnIsosceles Triangleis one in which two of the sides are equal. Seefig. 51.AnEquilateral Triangleis one in which the three sides are equal. AnEquiangular Triangleis one having its three angles equal. AnAcute-Angled Triangleis one in which each angle is acute.ARight-Angled Triangleis one which has one of the angles a right angle. Seefig. 53.AnObtuse-Angled Triangleis one having an obtuse angle.Fig. 54.Equiangular triangles are also equal sided, and vice versa.VERTICAL.—Upright or perpendicular. Vertical and perpendicular are not synonymous terms.VERTEX.—SeeAngle,Quadrilateral,Triangle. The vertex of a solid is the point in which its axis intersects the lateral surface.VIEW.—SeeElevation. Views are called front, top, right or left side, back, or bottom, according as they are made on the different planes of projection. They are also sometimes named according to the part of the object shown, as edge view, end view, or face view.WORKING DRAWING.—One which gives all the information necessary to enable the workman to construct the object.
ALTITUDE.—This is the elevation of an object above its base, or the perpendicular distance between the top and bottom of a figure.
AngleFig. 33.Right angleFig. 34.Acute angleFig. 35.Obtuse angleFig. 36.AnglesFig. 37.
AngleFig. 33.
Fig. 33.
Right angleFig. 34.
Fig. 34.
Acute angleFig. 35.
Fig. 35.
Obtuse angleFig. 36.
Fig. 36.
AnglesFig. 37.
Fig. 37.
ANGLEis the difference in the direction of two lines which meet or tend to meet. The lines are calledthe sidesand the point of meeting, thevertexof the lines.
To make an angle apparent, the two lines must meet in a point, asA BandA C, which meet in the pointA, as shown infig. 33.
Angles are measured by degrees.
ADegreeis one of the three hundred and sixty equal parts of the space about a point in a plane.
Angles are distinguished in respect to magnitude by the terms Right, Acute and Obtuse Angles.
ARight Angleis that formed by one line meeting another, so as to make equal angles with that other.
The lines forming a right angle areperpendicular to each other.
AnAcute Angleis less than a right angle. SeeFig. 35.
AnObtuse Angleis greater than a right angle. SeeFig. 36.
Obtuse and acute angles are also calledoblique angles; and lines which are neither parallel nor perpendicular to each other are calledoblique lines.
TheVertexorApexof an angle is the point in which the including lines meet.
An angle is commonly designated by a letter at its vertex; but when two or more angles have their vertices at the same point, they cannot be thus distinguished.
For example, when the three linesA B,A C, andA Dinfig. 37meet in the common pointA, we designate either of the angles formed, by three letters, placing that at the vertex between those at the opposite extremities of the including lines. Thus, we say, the angleB A C, etc.
APEX.—The summit or highest point of an object.
ARC.—Seecircle.
AXIS OF A SOLID.—An imaginary straight line passing through its center.
AXIS OF A FIGURE.—A straight line passing through the center of a figure, and dividing it into two equal parts.
BASE.—The base of a solid figure is that on which it stands—the lowest part.
BISECT.—To divide into two equal parts.
BISECTOR.—A line which bisects.
CircleFig. 38.
Fig. 38.
CIRCLE.—ACircleis a plane figure bounded by one uniformly curved line, all of the points in which are at the same distance from a certain point within, called theCenter.
TheCircumferenceof a circle is the curved line that bounds it.
TheDiameterof a circle is a line passing through its center, and terminating at both ends in the circumference, asA C B.
TheRadiusof a circle is a line extending from its center to any point in the circumference. It is one-half of the diameter. All the diameters of a circle are equal, as are also all the radiiC D,C BandC A.
AnArcof a circle is any portion of the circumference, asB DandA D.
Semi-Circle.—Half a circle formed by bisecting it with a diameter, asA C B.Fig. 38.
An angle having its vertex at the center of a circle is measured by the arc intercepted by its sides. Thus, the arcA Dmeasures the angleA C D, and in general, to compare different angles, we have but to compare the arcs, included by their sides, of the equal circles having their centers at the vertices of the angles.
CIRCUMSCRIBE.—To draw a line of figures about or outside, such as a circle drawn around a square touching its corners or angles.
Inscribe.—To draw a line or figure inside or on the interior, such as a circle drawn within a square touching its sides.
CONCAVE.—Curving inwardly.
CONE.—A solid body or figure having a circle for its base, and its top terminated in a point or vertex.
CONSTRUCTION.—The making of any object.
CONTOUR.—The outline of the general appearance of an object.
CONVERGENCE.—Lines extending towards a common point.
CONVEX.—Rising or swelling into a round form—the opposite to concave.
CORNER.—The point of meeting of the edges of a solid, or the two sides of a plane figure.
CROSS-HATCHES.—In free-hand drawing the use of lines crossing each other to produce light and shade effects.
CURVE.—A line of which no part is straight.
Reversed Curve.—One whose curvature is first in one direction and then in the opposite direction.
Spiral Curve.—A plain curve which winds about and recedes, according to some law, from its point of beginning, which is called its center.
CYLINDER.—A solid bounded by a curved surface and by two opposite faces called bases; the bases may be any curved figures and give the name to the cylinder; thus a circular cylinder is one whose bases are circles.
CYLINDRICAL.—Having the general form of a cylinder.
DEGREE.—The 360th part of a circle.
DESCRIBE.—To make or draw a curved line; to draw a plan.
DESIGN.—Any arrangement or combination to produce desired results in industry or art. To delineate a form or figure by drawing the outline—a sketch.
DEVELOP.—To unroll or lay out.
DIAGONAL.—A right line drawn from angle to angle of a quadrilateral or many angled figure and dividing it into two parts.
DIAMETER.—A right line passing through the center of a circle or other round figure terminated by the curve and dividing the figure symmetrically into two equal parts.
EDGE.—The intersection of any two surfaces.
ELEVATION.—The term elevation, vertical projection andfront view—applied to drawings—all have the same meaning.
FACE.—One of the plane surfaces of a solid; it may be bounded by straight or curved edges.
FINISHING.—Completing a drawing whose lines have been determined by erasing unnecessary lines and strengthening and accentuating where this is needed.
FORESHORTENING.—Apparent decrease in length, owing to objects being viewed obliquely; thus a wheel, when seen obliquely, instead of appearing round, presents the appearance of an ellipse.
FREE-HAND.—Executed by the hand unaided by instruments.
GENERATED.—Produced by.
GEOMETRIC.—According to geometry.
HALF-TINT.—The shading produced by means of parallel equidistant lines.
HEMISPHERE.—Half a sphere obtained by bisecting a sphere by a plane.
HORIZONTAL.—Parallel to the surface of smooth water. In drawing, a line drawn parallel to the top and bottom of the sheet is called horizontal.
INSCRIBE.—Seecircumscribe—its opposite.
INSTRUMENTAL.—By the use of instruments.
LINE.—A line has length, only, as A C; a right line is a straight line, the shortest line that can be drawn between two points, A——C.
Straight.One which has the same direction throughout its entire length.
Curved.One no part of which is straight.
Broken.One composed of different successive straight lines.
Mixed.One of straight and curved lines.
Center.A line used to indicate the center of an object.
Construction.A working line used to obtain required lines.
Dotted.A line composed of short dashes.- - - - - -
Dash.A line composed of long dashes.— — —
DotandDash. A line composed of dots and dashes alternating.— · — · —
Dimension.A line upon which a dimension is placed.
Full.An unbroken line, usually representing a visible edge.———
Shadow.A line about twice as wide as the ordinary full line.
A straight line is often called simply a line, and a curved line a curve.
LONGITUDINAL.—In the direction of the length of an object.
MODEL.—A form used for study.
OBLIQUE.—Neither horizontal nor vertical.
OBLONG.—A rectangle with unequal sides.
OVAL.—A plane figure resembling the longitudinal section of an egg; or elliptical in shape.
OVERALL.—The entire length.
PARALLEL.—Having the same direction and everywhere equally distant.
PATTERN.—That which is used as a guide or copy in making things.
Flat.One made of paper or other thin material.
Solid.One which reproduces the form and size of the object to be made.
PERIMETER.—The boundary of a closed plane figure.
PERPENDICULAR.—At an angle of 90°.
PERSPECTIVE.—View; drawing objects as they appear to the eye from any given distance and situation, real or imaginary.
PLAN.—Plan, horizontal projection andtop viewhave the same meaning.
PLANE FIGURE.—A part of a plane surface bounded by straight or curved lines, or by both combined.
PolygonFig. 39.
Fig. 39.
POLYGON.—A plane figure bounded by straight lines called the sides of the polygon. The least number of sides that can bound a polygon is three. Polygons bounded by a greater number of sides than four are denominated only by the number of sides.
A polygon of five sides is called aPentagon; of six, aHexagon; of seven, aHeptagon; of eight, anOctagon; of nine, aNonagon, etc.
Diagonalsof a polygon are lines joining the vertices of angles not adjacent.
ThePerimeterof a polygon is its boundary considered as a whole.
TheBaseof a polygon is the side upon which the polygon is supposed to stand.
TheAltitudeof a polygon is the perpendicular distance between the base and a side or angle opposite the base.
ParallelogramFig. 40.
Fig. 40.
AQuadrilateralis a polygon having four sides and four angles.
AParallelogramis a quadrilateral which has its opposite sides parallel.
The side upon which a parallelogram stands and the opposite side are called respectively its lower and upper bases.
ARectangleis a parallelogram having its angles right angles.
ASquareis an equilateral rectangle,fig. 41.
SquareFig. 41.RhombusFig. 42.TrapeziumFig. 43.TrapezoidFig. 44.
SquareFig. 41.
Fig. 41.
RhombusFig. 42.
Fig. 42.
TrapeziumFig. 43.
Fig. 43.
TrapezoidFig. 44.
Fig. 44.
PolyhedronsFigs. 45-49.
Figs. 45-49.
ARhomboidis an oblique-angled parallelogram.
ARhombusis an equilateral rhomboid,fig. 42.
ATrapeziumis a quadrilateral having no two sides parallel,fig. 43.
ATrapezoidis a quadrilateral in which two opposite sides are parallel, and the other two oblique,fig. 44.
A POLYHEDRONis a solid bounded by planes. There are five regular solids which are shown infigs. 45, 46, 47, 48 and 49. A regular solid is bounded by similar and regular plane figures.
Fig. 45.—Thetetrahedron, bounded by four equilateral triangles.
Fig. 46.—Thehexahedron, or cube, bounded by six squares.
Fig. 47.—Theoctahedron, bounded by eight equilateral triangles.
Fig. 48.—Thedodecahedron, bounded by twelve pentagons.
Fig. 49.—Theicosahedron, bounded by twenty equilateral triangles.
PRISM.—A solid whose bases or ends are very similar plane figures, and whose sides are parallelograms; prisms are called triangular, square, etc., according as the bases are triangles, squares, etc.
PRODUCE.—To continue or extend.
PROFILE.—An outline or contour.
PROJECTION.—The view of an object obtained upon a plane by projecting lines perpendicular to the plane.
QUADRANT.—The fourth part; a quarter; the quarter of a circle.
QUADRISECT.—To divide into four equal parts.
SECTION.—A projection upon a plane parallel to a cutting plane which intersects any object. The section generally represents the part behind the cutting plane, and represents the cut surfaces by diagonal lines.
SECTIONAL.—Showing the section made by a plane.
SHADOW.—Shade and shadow have about the same meaning.
SOLID.—A solid has three dimensions—length, breadth and thickness.
SPHERE.—A solid bounded by a curved surface every point of which is equally distant from a point within called the center.
SURFACE.—The boundary of a solid. It has but two dimensions—length and breadth. Surfaces are plane or curved.
APlane Surfaceis one upon which a straight line can be drawn in any direction.
ACurved Surfaceis one no part of which is plane.
The surface of the sphere is curved in every direction, while the curved surfaces of the cylinder and cone are straight in one direction.
The surface of a solid is no part of the solid, but is simply the boundary of the solid. It has two dimensions only, and any number of surfaces put together will give no thickness.
TriangleFig. 50.TriangleFig. 51.TriangleFig. 52.
TriangleFig. 50.
Fig. 50.
TriangleFig. 51.
Fig. 51.
TriangleFig. 52.
Fig. 52.
TriangleFig. 53.TriangleFig. 54.
TriangleFig. 53.
Fig. 53.
TriangleFig. 54.
Fig. 54.
SYMMETRY.—Design.A proper adjustment or adaptation of parts to one another and to the whole.
TRISECT.—To divide into three equal parts.
TRIANGLE.—A triangle is a polygon having three sides and three angles.Triis a Latin prefix signifying three; hence a Triangle is literally a figure containing three angles.
AScalene Triangleis one in which no two sides are equal. Seefig. 50.
AnIsosceles Triangleis one in which two of the sides are equal. Seefig. 51.
AnEquilateral Triangleis one in which the three sides are equal. AnEquiangular Triangleis one having its three angles equal. AnAcute-Angled Triangleis one in which each angle is acute.
ARight-Angled Triangleis one which has one of the angles a right angle. Seefig. 53.
AnObtuse-Angled Triangleis one having an obtuse angle.Fig. 54.
Equiangular triangles are also equal sided, and vice versa.
VERTICAL.—Upright or perpendicular. Vertical and perpendicular are not synonymous terms.
VERTEX.—SeeAngle,Quadrilateral,Triangle. The vertex of a solid is the point in which its axis intersects the lateral surface.
VIEW.—SeeElevation. Views are called front, top, right or left side, back, or bottom, according as they are made on the different planes of projection. They are also sometimes named according to the part of the object shown, as edge view, end view, or face view.
WORKING DRAWING.—One which gives all the information necessary to enable the workman to construct the object.
Knife
FREEHAND DRAWING
Free(-)hand DrawingFig. 55.
Fig. 55.