ClipArt ETC
Projections of a line's true length by revolving horizontal projection.

Projections of a Line

Projections of a line's true length by revolving horizontal projection.

Projections of a line's true length by revolving vertical projection.

Projections of a Line

Projections of a line's true length by revolving vertical projection.

Illustration of crossed polygon. This is not generally considered to be a real polygon.

Crossed Polygon

Illustration of crossed polygon. This is not generally considered to be a real polygon.

Decagon, a 10-sided polygon.

Decagon

Decagon, a 10-sided polygon.

Illustration of a square inscribed in a square that is inscribed in another square. Each successive square is rotated 45° in relation to the previous square. Line segments are drawn connecting the vertices of the smallest to the vertices of the largest square.

Squares Inscribed In Squares

Illustration of a square inscribed in a square that is inscribed in another square. Each successive…

Illustration of 2 concentric squares whose vertices are connected by line segments.

2 Concentric Squares

Illustration of 2 concentric squares whose vertices are connected by line segments.

Illustration of a regular hexagon with each side divided into thirds by line segments extended to the opposite side.

Regular Hexagon With Segments

Illustration of a regular hexagon with each side divided into thirds by line segments extended to the…

A large circle containing 2 smaller congruent circles. The small circles are externally tangent to each other and internally tangent to the larger circle. The horizontal line of centers of the small circles contains the diameter of the larger circle.

2 Smaller Horizontally Placed Circles In A Larger Circle

A large circle containing 2 smaller congruent circles. The small circles are externally tangent to each…

A large circle containing 2 smaller congruent circles. The small circles are externally tangent to each other and internally tangent to the larger circle. The vertical line of centers of the small circles contains the diameter of the larger circle.

2 Smaller Vertically Placed Circles In A Larger Circle

A large circle containing 2 smaller congruent circles. The small circles are externally tangent to each…

Illustration of concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter is equal to the length of the major axes of the ellipses. The ellipses, which decrease in width in equal increments until the smallest one is a line, are externally tangent to the circle. The illustration could be described as a circle rotated about the poles of the vertical axis. It could also be used as a 3-dimensional drawing of a sphere.

Ellipses Inscribed In A Circle

Illustration of concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter…

Illustration of concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter is equal to the length of the major axes of the ellipses. The ellipses, which decrease in width in equal increments until the smallest one is a line, are externally tangent to the circle. The illustration could be described as a circle rotated about the poles of the vertical axis. It could also be used as a 3-dimensional drawing of a sphere.

Ellipses Inscribed In A Circle

Illustration of concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter…

Illustration showing the construction of a golden rectangle. Beginning with a unit square, a line is then drawn from the midpoint of one side of the square to its opposite corner. Using that line, an arc is drawn that defines the length of the rectangle. Two quantities are considered to be in the golden ratio if (a+ b)/a = a/b which is represented by the Greek letter phi.

Construction Of A Golden Rectangle

Illustration showing the construction of a golden rectangle. Beginning with a unit square, a line is…

Diagrammatic representation of a segment of the axial skeleton V, a vertebra; C, Cv, ribs articulating above with the body and transverse process of the vertebra; S, the breastbone. The lighter-shaded part between S and C is the costal cartilage.

Segment of the Axial Skeleton

Diagrammatic representation of a segment of the axial skeleton V, a vertebra; C, Cv, ribs articulating…

A section through the cochlea in the line of its axis.

The Cochlea of the Ear

A section through the cochlea in the line of its axis.

Leaves - simple; alternate, edge entire. Outline - long oval or long egg-shape. Apex - pointed. Base - pointed or rounded. Leaf - three to five inches long, thickish; dark and smooth, usually shining, above; below dull, with ribs curved and irregular and minutely downy. On the upper surface the ribs are quite indistinct, except as the lea is held toward the light when they appear almost transparent. In the same position the left is seen also to be edged with a slight delicate fringe (appearing in the dried leaf like a line of yellow light). Bark - of trunk dark and rough. Flowers - greenish-yellow and small, at the base of the leaf-stems. June. Fruit - about one inch in diameter, rounded, nearly stemless, orange-red when ripe, with about eight large flat seeds. After frost it is of very pleasant flavor, before, exceedingly "puckery." Found - from Connecticut southward to Florida and westward to Southeastern Iowa. General Information - A tree twenty to sixty feet high; sometimes, at the South, more than one hundred feet high. The wood is hard and close-grained; the bark tonic and astringent. From two Greek words meaning fruit of Jove.

Genus Diospyros, L. (Persimmon)

Leaves - simple; alternate, edge entire. Outline - long oval or long egg-shape. Apex - pointed. Base…

Leaves - Simple; indeterminate in position because of their closeness; arranged singly up and down the branchlets, at first radiating about equally on every side, afterward flattened into two ranks, as in the Hemlock. Leaf - one half to one inch long, narrow; apex blunt or notched; edge entire; flat, with a grooved line above and a corresponding raised line below; bright green above; silvery white below. Bark - smooth and unbroken (especially when young), and usually covered with "blisters." Cones - two to four inches long, one inch broad, erect, at the sides of the branchlets; violet-colored. Scales - thin and flat, broad and rounded. The thin bracts between the scales are tipped with a slender bristle. The cone falls apart when ripe. Found - from the far North through the Northern States to Pennsylvania, and along the Alleghany Mountains to the high peaks of West Virginia. Common northward in damp forests. General Information - A slender, evergreen tree, twenty to sixty feet high; pyramid-shaped, with regular horizontal branches; its wood is very light and soft. From the "blisters," which form under the bark of the trunk and branches, the valuable Canada balsam is obtained. The tree is short-lived, and therefore of less value in cultivation.

Genus Abies, Link. (Fir)

Leaves - Simple; indeterminate in position because of their closeness; arranged singly up and down the…

Leaves - simple; indeterminate in position because of their smallness and closeness. They are scale-like, somewhat egg-shape, overlapping each other, and closely pressed in four rows up and down the very flat branchlets. Each leaf has at its centre a raised gland, easily distinguished if held between the eye and the light. Bark - fibrous. The "spray" (formed from the flat branchlets) is itself flat and very delicate and of a dull green. Cones - about one fourth of an inch in diameter, round, variously placed, compact, purplish as they ripen; opening when ripe toward the centre line (i. e., not toward its base). Scales - fleshy, shield-shaped and apparently fastened near their centres, with the edge several-pointed, and with a sharp point or knob in the centre. Seeds - usually four to eight under each scale, oval, with wide wings at the sides. Found - in deep, cold swamps (filling them densely and exclusively), from Southern Maine along the coast to Florida, and along the Gulf coast to Mississippi. General Information - A tapering evergreen tree, thirty to seventy feet high, with light and durable wood, largely used in boat-building, for wooden-ware, shingles, etc.

Genus Chamaecyparis, Spach. (White Cedar)

Leaves - simple; indeterminate in position because of their smallness and closeness. They are scale-like,…

Parts of two hairs embedded in their follicles. Labels: a, the skin, which is seen to dip down and line the follicle; b, the subcutaneous tissue; c, the muscles of the hair follicle, which by their contraction can erect the hair; o, sebaceous gland.

Hairs and their Follicles

Parts of two hairs embedded in their follicles. Labels: a, the skin, which is seen to dip down and line…

An erasing shield of thin metal is convenient in erasing desired shapes.

Straight Line Erasing Shield

An erasing shield of thin metal is convenient in erasing desired shapes.

Section of the head showing the greater scythe, the horizontal apophysis of the dura mater between the brain and the cerebellum and other parts under the middle line of the head.

Head, Section of

Section of the head showing the greater scythe, the horizontal apophysis of the dura mater between the…

For drawing straight lines and curves that are not arcs of circles, the ruling pen is used. The distance between the pen points, which regulates the width of line to be drawn, is adjusted by the thumb screw, and the blades are given a slight curvature so that there will be a cavity for ink when the points are close together.

Ruling Pen

For drawing straight lines and curves that are not arcs of circles, the ruling pen is used. The distance…

Circle pattern exercise: Draw diagonals A C and D B, and with the T-square draw the line E H. Now mark off on E H distances of 1.4 inch, and with H as a center describe, by means of the compasses, circles having radii respectively 2 inches, 1.5 inches, 1 inch, 0.75 inch, 0.5 inch, and .25 inch. Similarly with H as a center and a radius of 1.75 inch and 1.25 inches respectively raw the arcs F G and I J and K L and M N, being careful to end the arcs in the diagonals.

Circle Exercise

Circle pattern exercise: Draw diagonals A C and D B, and with the T-square draw the line E H. Now mark…

All lines in a mechanical drawing are made with the aid of an instrument. Horizontal lines are drawn with the upper edge of the T-square blade as a guide.

Drawing a Horizontal Line

All lines in a mechanical drawing are made with the aid of an instrument. Horizontal lines are drawn…

Vertical lines are drawn by using a triangle held against the T-square.

Drawing a Vertical Line

Vertical lines are drawn by using a triangle held against the T-square.

Parallel lines are drawn by using a triangle in combination with a T-square. To draw a line parallel to the one given, place a triangle against the T-square and move them together until the hypotenuse of the triangle matches the line. Hold the T-square firmly and slide the triangle in the direction of the arrow until the desired position of the parallel line is reached.

Drawing Parallel Lines Exercise

Parallel lines are drawn by using a triangle in combination with a T-square. To draw a line parallel…

Lines perpendicular to each other may be drawn by using a triangle in combination with the T-square. To draw a line perpendicular to a given line place a triangle against the T-square and move them together until the hypotenuse of the triangle matches the line. Turn the triangle on its right angled corner until the perpendicular line can be drawn on the hypotenuse of the triangle.

Drawing Perpendicular Lines Exercise

Lines perpendicular to each other may be drawn by using a triangle in combination with the T-square.…

A serious membrane. These line all closed cavities, or sac, of the body, and are reflected over the organs contained in them. They form a shut sac, completely excluding the air.

Serous Membrane

A serious membrane. These line all closed cavities, or sac, of the body, and are reflected over the…

A portion of the stomach, showing its internal surface or mucous coat. Mucous membranes line various cavities of the body, which are exposed to the air.

Mucous Membrane

A portion of the stomach, showing its internal surface or mucous coat. Mucous membranes line various…

Do not hold the pen over the drawing while filing. Keep the blades parallel to the direction of the line

Pen Positioning

Do not hold the pen over the drawing while filing. Keep the blades parallel to the direction of the…

Always draw a circle in one stroke, inclining the compass in the direction of the line and rolling the handle between the thumb and finger.

Inking a Circle

Always draw a circle in one stroke, inclining the compass in the direction of the line and rolling the…

The word "Monday" as clothes on a line drying in the sun.

Monday Banner

The word "Monday" as clothes on a line drying in the sun.

The line of characters and their actions in order for the pig to go over the stile.

Old Woman and Animals

The line of characters and their actions in order for the pig to go over the stile.

"a, a', impressions of the muscles; p, pallial line; s, bend occupied by the siphon; h, hinge; c, t, t', teeth." -Cooper, 1887

Clamshell

"a, a', impressions of the muscles; p, pallial line; s, bend occupied by the siphon; h, hinge; c, t,…

"Diagram illustrating the position of the groundwater surface (the dotted line) in a region of undulating topography." -Salisbury, 1919

Groundwater Position

"Diagram illustrating the position of the groundwater surface (the dotted line) in a region of undulating…

The diagram shows how to determine North by sun and plumb line.

Determining North

The diagram shows how to determine North by sun and plumb line.

"Tobacco split worm: adult moth above; larva below at right; pupa below at left, with side view of enlarged anal segment." -Department of Agriculture, 1899

Tobacco Split Worm

"Tobacco split worm: adult moth above; larva below at right; pupa below at left, with side view of enlarged…

"Heliothis armiger: a moth; b, dark larva; c, lighter larva entering pod; d, pupa; e, last segment of same, ventral view." -Department of Agriculture, 1899

Boll Worm Stages

"Heliothis armiger: a moth; b, dark larva; c, lighter larva entering pod; d, pupa; e, last segment of…

"A, diagram showing relative position of the guard cells in cross section in the open and closed positions; the heavier line indicates the open position." -Stevens, 1916

Stoma Guard Cells

"A, diagram showing relative position of the guard cells in cross section in the open and closed positions;…

"Diagram to show the relation of the food-conducting tissues of the leaf to those of the stem; and in the stem the relation of these tissues of one year to those of preceding years. The dotted line between phloem and xylem stands for the cambium. The figures at the bottom of the diagram indicate the age in years of the zones of tissues in phloem and xylem." -Stevens, 1916

Food Tissues

"Diagram to show the relation of the food-conducting tissues of the leaf to those of the stem; and in…

"Where the sea bottom has a very gentle slope, the waves break at some distance from the shore and the sand they carry is deposited, forming a barrier beach (B) along the line of greatest disturbance. The strip of water inclosed between the land and the barrier beach is called a lagoon (L)." -Dryer, 1901

Barrier Beach

"Where the sea bottom has a very gentle slope, the waves break at some distance from the shore and the…

"The line AB represents the surface of a water wave whose length is ai, moving in the direction of the long arrow. Suppose the wave length to be divided into eight equal parts, ab, bc, etc. If the water were still, the particles 1, 2, 3, etc., would lie directly above the points a, b, c, etc., but each particle is moving in a circular path in the direction shown by the curved arrows." -Dryer, 1901

Wave Movement

"The line AB represents the surface of a water wave whose length is ai, moving in the direction of the…

"BA is the ray of light passing through a rare medium (as, for instance, air); and upon its entrance into a denser medium (as, for instance, water) the ray will be deflected from the direction of its path BA, and will take the course AE. If the line CD is perpendicular to the dividing surface between the two media, then BAC is the angle of incidence and DAE is the angle of refraction." -Waldo, 1896

Atmospheric Optics

"BA is the ray of light passing through a rare medium (as, for instance, air); and upon its entrance…

Illustration of a compass with one leg at point A on the line segment and the other at Point B.

Compass and Line

Illustration of a compass with one leg at point A on the line segment and the other at Point B.

Illustration of a compass with one leg at point O on the line segment and the other at Point M.

Compass and Line

Illustration of a compass with one leg at point O on the line segment and the other at Point M.

A, the malleus, or mallet, with its long handle running down, to touch with its delicate extremity the membrane of the drum. B, is the incus, or anvil, nicely fitted to the mallet, and showing C, the orbicular bone placed between its termination, and D, the stirrup. The line a,b, represents the center of motion of the malleus, and c,d, the center of motion of the incus. Now this chain of bones acts on the principle of a long level, as a small motion at one end of a long pole serve to move it through a wide space at the other.

Bones of the Ear

A, the malleus, or mallet, with its long handle running down, to touch with its delicate extremity the…

Illustration showing two parallel vertical lines cut by a perpendicular line and a transversal. Congruent line segments are marked.

Parallel Lines Cut By a Perpendicular And Transversal

Illustration showing two parallel vertical lines cut by a perpendicular line and a transversal. Congruent…

Illustration used to show how to construct an equilateral triangle, with a given line as a side.

Construction Of Equilateral Triangle

Illustration used to show how to construct an equilateral triangle, with a given line as a side.

"Look through the rear-sight notch at the bull's-eye or mark and bring the top of the front sight on a line with the top of and in the center of the rear-sight notch and aligned upon the point of aim." -Moss, 1914

Normal Sight

"Look through the rear-sight notch at the bull's-eye or mark and bring the top of the front sight on…

"Trenches may be classified into fire trenches, cover trenches, and communication trenches, the first named being occupied by the firing line, the second by the supports, and the last by troops passing between the first and second." -Moss, 1914

Trenches

"Trenches may be classified into fire trenches, cover trenches, and communication trenches, the first…

The image represents the horizontal clock face system. The bottom is the firing line and the numbers of the clock references the position of other objects.

Horizontal Clock Face System

The image represents the horizontal clock face system. The bottom is the firing line and the numbers…

"Simple orthoclase crystal showing cleavage lines and the position of the twinning plane in a Carlsbad twin." -Johannsen, 1908

Orthoclase Crystal

"Simple orthoclase crystal showing cleavage lines and the position of the twinning plane in a Carlsbad…

"Cross-section through Ascaris. d.n., Dorsal nerve; n.c., non-contractile portion of muscle cells; c., cuticle; e., epidermis; l.l., lateral line; e.v., excretory vessel; m., contractile portion of muscle cells; v.n., ventral nerve; ov., ovary; ut., uterus; g., gut." -Thomson, 1916

Ascaris

"Cross-section through Ascaris. d.n., Dorsal nerve; n.c., non-contractile portion of muscle cells; c.,…

"Anterior region of earthworm. Note the eight setae (s.) on each segment. R.S., Spots between 9-10, 10-11, indicate openings of receptacula seminis; Ovd., openings of oviducts on segment 14/ vd., openings of vasa deferentia on segment 13." -Thomson, 1916

Earthworm

"Anterior region of earthworm. Note the eight setae (s.) on each segment. R.S., Spots between 9-10,…

"Ventral aspect of male cockroach with the wings extended. An imaginary median line has been inserted. A., antennae; E., eye; P.T., prothorax; W1, first pair of wings; W2, second pair of wings; C., cercus; St., style; Co., coxa; Tr., trochanter; F., femur; Ti., tibia; Ta., tarsus." -Thomson, 1916

Cockroach

"Ventral aspect of male cockroach with the wings extended. An imaginary median line has been inserted.…

"The fresh-water mussel...the inside of the shell (left valve)...u., The umbo; L., the ligament; c.t., lateral teeth; a.a., anterior adductor mark; a.r., mark of protractor of the foot; p.l., pallial line; p.a., posterior adductor mark; p.r., mark of posterior retractor of the foot; A., anterior (the blunter end); P., posterior." -Thomson, 1916

Freshwater Mussel

"The fresh-water mussel...the inside of the shell (left valve)...u., The umbo; L., the ligament; c.t.,…

"The fresh-water mussel...the outside of the shell (right valve)...u., The umbo; L., the ligament; l.g., a line of growth; A., anterior (the blunter end); P., posterior; V., ventral." -Thomson, 1916

Freshwater Mussel

"The fresh-water mussel...the outside of the shell (right valve)...u., The umbo; L., the ligament; l.g.,…

"Development of excretory system of vertebrate. The primitive segments are not separated off from the lateral plate, and the pronephros (pn.) is seen arising from the lower part of the primitive segment. n.c., nerve cord; nch., notochord; pn., pronephros; g., gut; p.s., primitive segment; mes., mesonephric tubule; pn.d., pronephric duct; b.c., body cavity; ao., aorta; siv., sub-intestinal vein, with vessel to the aorta." -Thomson, 1916

Excretory System Stage 1

"Development of excretory system of vertebrate. The primitive segments are not separated off from the…

"Development of excretory system of vertebrate. The pronephros is completely separated off from the primitive segment and lateral plate. n.c., nerve cord; nch., notochord; pn., pronephros; g., gut; p.s., primitive segment; mes., mesonephric tubule; pn.d., pronephric duct; b.c., body cavity; ao., aorta; siv., sub-intestinal vein, with vessel to the aorta." -Thomson, 1916

Excretory System Stage 2

"Development of excretory system of vertebrate. The pronephros is completely separated off from the…

"The origin of the mesonephric tubules is seen. They arise from the upper part of the lateral plate, which is now completely separated from the primitive segment, and curving round the pronephric duct come to open into it. n.c., nerve cord; nch., notochord; pn., pronephros; g., gut; p.s., primitive segment; mes., mesonephric tubule; pn.d., pronephric duct; b.c., body cavity; ao., aorta; siv., sub-intestinal vein, with vessel to the aorta." -Thomson, 1916

Excretory System Stage 3

"The origin of the mesonephric tubules is seen. They arise from the upper part of the lateral plate,…

"External characters of a Teleostean--a carp (Cyprinus carpio). R., Dorsal unpaired fin; S., homocercal caudal fin; A., anal fin; B., B., pectoral and pelvic paired fins. Note also the lateral line and barbule." -Thomson, 1916

Carp

"External characters of a Teleostean--a carp (Cyprinus carpio). R., Dorsal unpaired fin; S., homocercal…