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Red-Maple branch, with accessory buds placed side by side. The annular lines toward the base are scars of the bud-scales, and indicate the place of the winter-bud of the preceding year.

Red-Maple branch

Red-Maple branch, with accessory buds placed side by side. The annular lines toward the base are scars…

The investing sheaths or dead leaf-bases striped off. The faint cross-lines represent the scars, where the leaves were attached, i.e. the nodes: the spaces between are the internodes. The exhausted corm of the previous year is underneath; forming ones for next year on the summit and sides.

Corm of a Crocus

The investing sheaths or dead leaf-bases striped off. The faint cross-lines represent the scars, where…

The romantisit, J. William Turner, was famous for his drawings of landscapes such as: lakes, castles, ruins, ships and coast lines. The painting was recently sold for $1,000,000.

Light-Towers of the Heve

The romantisit, J. William Turner, was famous for his drawings of landscapes such as: lakes, castles,…

The romantisit, J. William Turner, was famous for his drawings of landscapes such as: lakes, castles, ruins, ships and coast lines. In this picture he displays his technique. The piece is from the "Rivers of France".

Chateau D'Amboise

The romantisit, J. William Turner, was famous for his drawings of landscapes such as: lakes, castles,…

These zones, which are separated by the parallels of latitude, are generally termed the <em>astronomical</em> or <em>mathematical zones</em> to distinguish them from others called <em>physical zones</em>, which are bounded by the lines of mean annual temperature.

Mathematical Climate Zones

These zones, which are separated by the parallels of latitude, are generally termed the astronomical…

Corm of a Crocus, the investing sheaths or dead leaf-bases stripped off. The faint cross-lines represent the scars, where the leaves were attached, i. e. the nodes: the spaces between are the internodes. The exhausted corm of the previous year is underneath; forming ones for next year on the summit and sides.

Crocus

Corm of a Crocus, the investing sheaths or dead leaf-bases stripped off. The faint cross-lines represent…

Diagram of the calyx and corolla; the three dotted lines in the place of missing petals.

Monkshood

Diagram of the calyx and corolla; the three dotted lines in the place of missing petals.

Diagram of a cross section of an exogenous stem, the wedges filling the space, separated only by the thin lines, or medullary rays, running from pith to bark.

Exogenous Stem

Diagram of a cross section of an exogenous stem, the wedges filling the space, separated only by the…

The cross-ratio of four points in a line is equal to the cross-ratio of their projections on any other line which lies in the same plane with it.

Cross-Ratio Four Points

The cross-ratio of four points in a line is equal to the cross-ratio of their projections on any other…

The lines which join corresponding points in an involution on a conic all pass through a fixed point; and reciprocally, the points of intersection of conjugate lines in an involution among tangents to a conic lie on a line.

Conic Involution

The lines which join corresponding points in an involution on a conic all pass through a fixed point;…

The lines joining any point on a conic to the two foci are equally inclined to the tangent and normal at that point. This is an ellipse.

Conic Foci Involution

The lines joining any point on a conic to the two foci are equally inclined to the tangent and normal…

To find the angle between two given lines a, b of which the projections a1, b1 and a2, b2 are given.

Angle of Two Lines

To find the angle between two given lines a, b of which the projections a1, b1 and a2, b2 are given.

Intersection of lines between a circle and its polar point.

Circle Polar Point

Intersection of lines between a circle and its polar point.

Uniting the theories of partial polygons of resistance and centres and lines of resistance, this buttress of blocks illustrates the tangential curve that is the line of pressures.

Buttress of Blocks

Uniting the theories of partial polygons of resistance and centres and lines of resistance, this buttress…

The lines of contact are equal, but the axes are neither parallel to each other, or the line of contact.

Lateral Sliding Contact

The lines of contact are equal, but the axes are neither parallel to each other, or the line of contact.

Two arrangements of pulley: crossed belt and uncrossed belt. The pulleys are constructed with two circles that have the radii labeled and tangent lines drawn (strings).

Pulley

Two arrangements of pulley: crossed belt and uncrossed belt. The pulleys are constructed with two circles…

Dotted lines can indicate a relationship among figures, such as one inside another.

Drawing Lines 1

Dotted lines can indicate a relationship among figures, such as one inside another.

Shading of the right and lower sides gives dimension to drawings.

Drawing Lines 2

Shading of the right and lower sides gives dimension to drawings.

Top and side views of a hexagonal pyramid shaded with dimension lines.

Drawing Lines 3

Top and side views of a hexagonal pyramid shaded with dimension lines.

Circles should be unshaded or shaded evenly with thick and thin lines, changing at about 45 degrees.

Drawing Lines 4

Circles should be unshaded or shaded evenly with thick and thin lines, changing at about 45 degrees.

Different surfaces can be indicated by changing the pattern or direction of lines.

Drawing Sections

Different surfaces can be indicated by changing the pattern or direction of lines.

Draftsman's second method for drawing a parabola

Parabola Second Method

Draftsman's second method for drawing a parabola

A simple complete joint, one type of movable articulation. The synovial membrane is represented by dotted lines. They have a secreting membrane placed between their opposing surfaces, which keeps them well lubricated and capable of free movement one upon the other.

A Simple Complete Joint

A simple complete joint, one type of movable articulation. The synovial membrane is represented by dotted…

Section of the internal saphenous nerve. Stained in osmic acid and subsequently hardened in alcohol. Drawn as seen under a very low magnifying power. Labels: ep, epineurium (general sheath of the nerve consisting of connective tissue separated by cleft-like areolae, which appear as a network of clear lines, with here and there fat-cells), f, f, and blood-vessels, v; per, perineurium (particular sheath of funiculus); end, endoneurium, or connective tissue within funiculus, embedded in which are seen the cut ends of the medullated nerve fibers. The fat cells and the nerve fibers are darkly stained by the osmic acid.

Section of the Internal Saphenous Nerve

Section of the internal saphenous nerve. Stained in osmic acid and subsequently hardened in alcohol.…

"...in this figure the thicker lines are the projections of the three planes of symmetry, and on these lie the poles of the rhombehedra (six of which are indicated)." -The Encyclopedia Britannica 1910

Stereographic Projection of a Holosymmetric Rhombohedral Crystal

"...in this figure the thicker lines are the projections of the three planes of symmetry, and on these…

Regions of the abdomen and their contents (edge of costal cartilages in dotted outline). "For convenience of description the abdomen may be artificially divided into nine regions by drawing two circular lines around the body parallel with the cartilages of the ninth ribs, and the highest point of the crests of the ilia; and two vertical lines from the cartilage of the eighth rib on each side to the center of Poupart's ligament. The vicar contained in these different regions are as follows: -- Right Hypochondriac - the right lobe of the liver and gall-bladder, hepatic flexure of the colon, and part of the right kidney. Right Lumbar - ascending colon, part of the right kidney, and some convolutions of the small intestines. Right Inguinal (Iliac) - the caecum, appendix caeci. Epigastric Region - the middle and pyloric end o the stomach, left lobe of the liver, the pancreas, the duodenum, part of the kidneys and the suprarenal capsules. Umbilical Region - the transverse colon, part of the great omentum and mesentery, transverse part of the duodenum, and some convolutions of the jejunum and ileum, and part of both kidneys. Hypogastric Region - convolutions of the small intestines, the bladder in children, and in adults if distended, and the uterus during pregnancy. Left Hypochondriac - the splenic end of the stomach, the spleen and extremity of the pancreas, the splenic flexure of the colon, and part of the left kidney. Left Lumbar - descending color, part of the omentum, part of the left kidney, and some convolutions of the small intestines. Left Inguinal (Iliac) - sigmoid flexure of the colon." &mdash; Kimber, 1907.

Regions of the Abdomen and their Contents

Regions of the abdomen and their contents (edge of costal cartilages in dotted outline). "For convenience…

"Electrification produced by rubbing dissimilar bodies together and then separating them. If the insulated glass and leather discs A and B be rubbed together, but not separated, no signs of electrification can be detected; but if the discs be drawn apart a little distance the space betwen them is found to be and electric field, and as they separate farther and farther, electric forces will be found to exist in more and more of the surrounding space, the electrification being indicated by 'lines of force.' " -Hawkins, 1917

Electrification

"Electrification produced by rubbing dissimilar bodies together and then separating them. If the insulated…

"Lines of force of a charged sphere and a conductor under induction. The negative electrification on the end a of the cylinder indicates that an equal number of lines set out from that end." -Hawkins, 1917

Lines of Force under Induction

"Lines of force of a charged sphere and a conductor under induction. The negative electrification on…

"Tracing lines of force with a suspended magnet." -Hawkins, 1917

Tracing magnetic field lines

"Tracing lines of force with a suspended magnet." -Hawkins, 1917

"Illustrating Maxwell's 'corkscrew rule' for relative directions of current and lines of force...a current flow through the wire ab in the direction from a to b, the magnetic lines will encircle the wire in the direction of the curved arrow ro which shows the direction in which the corkscrew must be turned to advance in the direction of the arrow n." -Hawkins, 1917

Maxwell's Corkscrew Rule

"Illustrating Maxwell's 'corkscrew rule' for relative directions of current and lines of force...a current…

"Experiment showing lines of force in the magnetic field surrounding a conductor carrying an electric current." -Hawkins, 1917

Magnetic Field

"Experiment showing lines of force in the magnetic field surrounding a conductor carrying an electric…

"Lines of force of a circular loop. If a current flow through the loop in the direction indicated, the lines of force both inside and outside the loop, will cross the plane of the loop at right angles, and all those which cross the loop on the inside will pass through the plane in one direction...while all on the outside will return through the plane in the opposite direction." -Hawkins, 1917

Lines of Force

"Lines of force of a circular loop. If a current flow through the loop in the direction indicated, the…

"Lines of force in a circular loop. If the loop pass through a piece of cardboard at right angles to its plane, and the curent flow as indicated, the dotted lines on the cardboard will represent the direction of the lines of force in the plane of the cardboard." -Hawkins, 1917

Lines of Force

"Lines of force in a circular loop. If the loop pass through a piece of cardboard at right angles to…

"Illustrating the effects of introducing an iron core into a solenoid. In the upper firgure, the air space or 'air core' surrounded by the solenoid offers considerable resistance to the passage of magnetic lines, allowing only a small number to pass through. If a pieve of iron be introduced, as in the lower figure, the number of lines will be greatly increased." -Hawkins, 1917

Effect of a metal core in a solenoid

"Illustrating the effects of introducing an iron core into a solenoid. In the upper firgure, the air…

"Experiment illustrating Lenz's Law. If a copper ring be held in front of an ordinary elecromagnet, and the current circulating through the coil of the magnet be in such a direction as to magnetize the core as indicated b the letters S N, then as the current increases in the coil more and more of the lines of force proceeeding from N pass through the ring OO from left to right." -Hawkins, 1917

Lenz's Law

"Experiment illustrating Lenz's Law. If a copper ring be held in front of an ordinary elecromagnet,…

"Fleming's rule for direction of induced current. Extend the thumb, forefinger and middle finger of the right hand [as shown]. Place the hand [so that] the thumb will point in the direction in which the conductor moves, the forefinger in the direction of the lines of force (N to S), then will the middle finger point in the direction in which the induced current flows." -Hawkins, 1917

Right Hand Rule of Induced Current

"Fleming's rule for direction of induced current. Extend the thumb, forefinger and middle finger of…

"The palm rule for direction of induced current: If the palm of the right hand be held against the direction of the lines of force, the thumb in the direction of the motion, then the fingers will point in the direction of the induced current." -Hawkins, 1917

Right Hand Rule, Palm

"The palm rule for direction of induced current: If the palm of the right hand be held against the direction…

"Distribution of magnetic lines through a ring armature. Since the lines follow the metal of the ring instead of penetrating the interior no electromotive force is induced in that portion of the winking lying on the interior surface of the ring. There is, therefore, a large amount of dead wire or wire that is ineffective in inducing electromotive force; that is the chief objective to the ring type of armature." -Hawkins, 1917

Distribution of Magnetic Lines, Ring Armature

"Distribution of magnetic lines through a ring armature. Since the lines follow the metal of the ring…

Simple pavement epithelium. Labels: a, from a serious membrane; b, from a blood vessel. "In simple pavement epithelium, the cells form flat, many-sided plates or scales, which fit together like tiles of a mosaic pavement. It forms very smooth surfaces, and it lines the alveoli of the lungs, the heart, blood vessels, land lymphatics; the mammary ducts, the serous cavities, etc."&mdash;Kimber, 1907.

Simple Pavement Epithelium Cells

Simple pavement epithelium. Labels: a, from a serious membrane; b, from a blood vessel. "In simple pavement…

A Diagrammatic section across the body in the chest region. Labels: x, the dorsal tube, which contains the spinal cord; the black mass surrounding it is a vertebra; a, the gullet (esophagus), a part of the alimentary canal; h, the heart; sy, sympathetic nervous system; ll, lungs; the dotted lines around them are the pleurae; rr, ribs; st, the breastbone.

Section Across the Body in the Chest Region

A Diagrammatic section across the body in the chest region. Labels: x, the dorsal tube, which contains…

Figure showing magnetic lines of force from a magnet, as well as both north and south poles.

Magnetic Field

Figure showing magnetic lines of force from a magnet, as well as both north and south poles.

"In a body of equal thickness, as a board, or a slab of marble, but otherwise of an irregular shape, the centre of gravity may be found by suspending it, first from one point, and then from another, and marking, by means of a plumb line, the perpendicular ranges from the point of suspension. the centre of gravity will be the point where these two lines cross each other." -Comstock 1850

Center of Gravity

"In a body of equal thickness, as a board, or a slab of marble, but otherwise of an irregular shape,…

"If a vessel be filled with water, and three apertures be made in its sie at E F G, the fluid will be thrown out in jets, falling to the earth in the curved lines shown." -Comstock 1850

Water Velocity and Gravity

"If a vessel be filled with water, and three apertures be made in its sie at E F G, the fluid will be…

"If the object a be placed obliquely before the convex mirror, then the converging rays from its two extremities falling obliquely on its surface, would they prolonged through the mirror, meet at the point c, behind it. But instead of being thus continued, they are thrown back by the mirror in less convergent lines, which meet the eye at e, it being, as we have seen, one of the properties of this mirror, to reflect converging rays less convergent than before." -Comstock 1850

Curved Image

"If the object a be placed obliquely before the convex mirror, then the converging rays from its two…

"...let us suppose the object a, to be placed before the mirror, and nearer to it than the principal focus. Then the rays proceeding from the extremities of the object without interruption, would continue to diverge in the lines o and n, as seen behind the mirror' but by reflection they are made to diverge less than before, and consequently to make the angle under which the meet more obtuse at the eye b, than it would be if they continued onward to e, where they would have met without reflection. The result therefore, is to render the image h, upon the eye, as much larger than the object a, as the angle at the eye is more obtuse than the angle at e." -Comstock 1850

Object Within the Focus in a Concave Mirror

"...let us suppose the object a, to be placed before the mirror, and nearer to it than the principal…

"Suppose a red hot ball to be placed in the principle focus of the mirror, a, the rays of heat and light proceeding from it will be reflected in the parallel lines 1, 2, 3 etc." -Comstock 1850

Reflection of Heat Using Concave Mirrors

"Suppose a red hot ball to be placed in the principle focus of the mirror, a, the rays of heat and light…

"Suppose the object o to be at such a distance, that the rays of light from it pass in parallel lines, p, p, to the great reflector, r, r. this reflector being concave, the rays are converged by reflection, and cross each other at a, b which the image is inverted. The rays then pass to the small mirror, b, which being also concave, they are thrown back in nearly parallel lines, and having passed the aperture in the centre of the great mirror, fall on the plano-convex lens e." -Comstock 1850

Refracting Telescope

"Suppose the object o to be at such a distance, that the rays of light from it pass in parallel lines,…

"Let any irregularly shpaed body, as a stone or chair, be suspended so as to move freely. Drop a plumb line from the point of the suspendsion, and make it fast or mark its direction. The center of mass will lie in this line. From a second point, not in the line already determined, suspend the body; let it fall a plumb line as before. The center of mass will lie in this line also. But to lie in both lines, it must lie at their intersection." -Avery 1895

Finding the Center of Mass

"Let any irregularly shpaed body, as a stone or chair, be suspended so as to move freely. Drop a plumb…

"Support, as shown, a glass or brass plate, square or round, and strew it evenly with fine sand. Place the finger at any point of the edge of the plate, so as to form a node there, and draw a violin bow at a point properly chosen. The sand immediately begins to dance on the plate and arrange itself along nodal lines. By changing the nodal points and bowing properly, other sand-figures may be produced, one of which is shown." -Avery 1895

Vibrating Plates

"Support, as shown, a glass or brass plate, square or round, and strew it evenly with fine sand. Place…

"When a charge is moved from any point to another point in the same equipotential surface, no work is done upon it. When a charge is moved from one such surface to another, the work done is independent of the path of transfer. If such a surface was to be rendered impenetrable, a particle could lie upon it without tendancy to move along it in any direction. If any two points in such a surface were to be joined by a conductor, no flow of electrification would take place. The closed lines are equipotential lines drawn, upon equipotential surfaces, about two similartly electrified spheres, the quantity of electrifaction at A being twice that at B." -Avery 1895

Equipotential Lines

"When a charge is moved from any point to another point in the same equipotential surface, no work is…

"If the conducting wire is bent into the form shown, the lines of force will pas around the wire from one face of the loop to the other, and in the direction indicated by the 'rule of thumb' just given." -Avery 1895

Magnetic Field Around a Current Carrying Wire

"If the conducting wire is bent into the form shown, the lines of force will pas around the wire from…

"Place a strip of shet iron in the solenoid, as shown...Hotice that most of the lines of force are gathered into the iron and issue from its ends. Notice that the lines curve outward and tend to return, forming closed loops or complete magnetic circuits. Change the iron from the inside of the solenoid to the outside, and repeat...Notice that the iron again gathers in the lines of force as if it offered an easier path for them." -Avery 1895

Solenoid with Iron Bar

"Place a strip of shet iron in the solenoid, as shown...Hotice that most of the lines of force are gathered…

"The magnetic poles of the earth do notc oincide with its geographical poles and, condequently, in some places, the magnetic needle does not point ot the geographical north. The angle that the axis of a compass-bneedle makes with the geographical meridian at any place is called the declination or variation of the needle at that place...Lines drawn through places on the earth where the declination is the sam are called isogonic lines, as shown." -Avery 1895

Isogonic Lines of Earth

"The magnetic poles of the earth do notc oincide with its geographical poles and, condequently, in some…

Diagram illustrating the muscles (drawn in thick black lines) which pass before and behind the joints, and by their balanced activity keep the joints rigid and the body erect.

Muscles

Diagram illustrating the muscles (drawn in thick black lines) which pass before and behind the joints,…

"In a body free to move, the center of gravity will lie in a vertical plumb-line drawn through the point of support. Therefore, to find the position of the center of gravity of an irregular solid, as the crank, Fig 8, suspended it at some point, as B, so that it will move freely. Drop a plumb line from the point of suspension and mark its direction. Suspend the body at another point, as A, and repeat the process. The intersection C of the two lines will be directly over the center of gravity." &mdash;Hallock 1905

Center of Gravity of a Solid

"In a body free to move, the center of gravity will lie in a vertical plumb-line drawn through the point…

A thin section through the gastric mucous membrane which lines the stomach, perpendicular to its surface, magnified about 25 diameters. a, a simple peptic gland; b, a compound peptic gland; c, a mucous gland.

Section through the Gastric Mucous Membrane

A thin section through the gastric mucous membrane which lines the stomach, perpendicular to its surface,…

"Slit A is a very small opening. The light coming from the soldier on the right shines through the slit in straight lines making the image of the soldier inverted on wall W." &mdash;Quackenbos 1859

Inverted Image

"Slit A is a very small opening. The light coming from the soldier on the right shines through the slit…

Straight line

Straight Line

Straight line

Curved line

Curved Line

Curved line

Broken line

Broken Line

Broken line