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Short piece of stem of Flax, magnified, showing the bark, wood, and pith in a cross section.

Stem of Flax

Short piece of stem of Flax, magnified, showing the bark, wood, and pith in a cross section.

The growing end of a branching Conferva (Cladophora glomerata), showing how, by a kind of budding growth, a new cell is formed by a cross partition separating the newer tip from the older part below; also, how the branches arise.

Conferva

The growing end of a branching Conferva (Cladophora glomerata), showing how, by a kind of budding growth,…

Joseph Warren, an American patriot killed at Breed's Hill.

Joseph Warren

Joseph Warren, an American patriot killed at Breed's Hill.

This painting, by Francesco Raibolini, was painted soon after 1500 for the Benedictines of Parma. The emotional expressions on the faces of the figures is apparent here. The piece can now be found in the Accademia in Parma.

Deposition from the Cross

This painting, by Francesco Raibolini, was painted soon after 1500 for the Benedictines of Parma. The…

Section through the closed left eye. 1. Lifting muscle 2. Upper Straight Muscle 3. Optic Nerve 4. Fatty Cushion 5. Lower straight muscle 6. Vitrous Humour 7. Lower cross muscle 8. Lower Eyelid 9. Upper eyelid 10. Crystalline lens

Eyeball

Section through the closed left eye. 1. Lifting muscle 2. Upper Straight Muscle 3. Optic Nerve 4. Fatty…

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…

Three-ranked arrangement, shown in a piece of the stalk of a Sedge. Diagram or cross-section, in one plane; showing two cycles of three.

Three-ranked

Three-ranked arrangement, shown in a piece of the stalk of a Sedge. Diagram or cross-section, in one…

Diagram of flower of Trillium. In this, as in all such diagrams of cross-section of blossoms, the parts of the outer circle represent the calyx; the next, corolla; within, stames (here in two circles of three each, and the cross-section is through the anthers); in the centre, section of three ovaries joined into a compound one of three cells.

Trillium

Diagram of flower of Trillium. In this, as in all such diagrams of cross-section of blossoms, the parts…

Cross section of an ovary of Hypericum graveolens with the placentae now separate and rounded.

Hypericum graveolens

Cross section of an ovary of Hypericum graveolens with the placentae now separate and rounded.

Diagram of a cross section of a very young exogenous stem, showing six woody bundles or wedges.

Exogenous Stem

Diagram of a cross section of a very young exogenous stem, showing six woody bundles or wedges.

Diagram of a cross section of a very young exogenous stem, showing twelve woody bundles or wedges.

Exogenous Stem

Diagram of a cross section of a very young exogenous stem, showing twelve woody bundles or wedges.

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…

Children on a hill, looking down upon a town.

Town

Children on a hill, looking down upon a town.

An image of a hill, valley, and river.

Hill

An image of a hill, valley, and river.

An image of a town viewed from upon a hill.

Town

An image of a town viewed from upon a hill.

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 sceptre with a cross, used since the restoration of the English monarchy.

English Royal Sceptre

The sceptre with a cross, used since the restoration of the English monarchy.

A cross-section of an acorn.

Cross-section of an acorn

A cross-section of an acorn.

A longitudinal section of an oat seed.

Cross-section of an oat seed

A longitudinal section of an oat seed.

A cross-section of an oat seed.

Cross-section of oat seed

A cross-section of an oat seed.

A cross-section of a ship.

Section of a ship

A cross-section of a ship.

A longitudual cross-section showing the interior of the Caronia.

Longitudinal section of the Caronia

A longitudual cross-section showing the interior of the Caronia.

"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…

"Ring armature of four pole dynamo; diagram of winding and connections, showing direction of the indced currents. the currents in the winding under the upper N and S poles are opposed to each other and flow to the external circuit by the positive brush 1, and back to this half of the armature by the negative brushes 3 and 4...The armature is said to be 'cross connected.' " -Hawkins, 1917

Ring Armature

"Ring armature of four pole dynamo; diagram of winding and connections, showing direction of the indced…

"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,…

"The angle under which the rays of light, coming from the extremities of an object, cross each other at the eye, bears a proportion directly to the length, and inversely to the distance of the object." -Comstock 1850

Angle of Vision

"The angle under which the rays of light, coming from the extremities of an object, cross each other…

"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,…

"Tenacity is that property of matter by virtue of which some bodies resist a force tending to pull their particles asunder Its measure is the ratio between the breaking weight and the area of the cross section of the body broken. It varies with different substances, with the form of the body, with the temperature, and with the duration of the pull." -Avery 1895

Testing for Tenacity

"Tenacity is that property of matter by virtue of which some bodies resist a force tending to pull their…

"Get a lamp-chimney, preferably cylindrical. With a diamond or a steel glass-cutter, cut a disk of window glass a little larger than the cross-section of the lamp-chimney. Pour some fine emery powder on the disk, and rub one end of the chimney upon it, thus grinding them until they fit accurately...place [the chimney] under the water as shown. the upward pressure of the water will hold the disk in place. Pour water carefully into the tube; the disk will fall as soon as the weight of the water in the chimney plus the weight of th disk, exceeds the upward pressure of the water." -Avery 1895

Water Pressure Experiment

"Get a lamp-chimney, preferably cylindrical. With a diamond or a steel glass-cutter, cut a disk of window…

Vertical section of the intestinal mucous membrane of the rabbit. Two villi are represented, in one of which the dilated lacteal alone is shown, in the other the blood vessels and lacteal are both seen injected, the lacteal white, the blood vessels dark; a, the lacteal vessels of the villi; a', horizontal lacteal, which they join; b, capillary blood vessels in one of the villi; c, small artery; d, vein; e, the epithelium covering the villi; g, tubular glands or crypts of Lieberkuhn, some divided down the middle, others cut more irregularly; i, the submucous layer. A, cross-section of three tubular glands more highly magnified.

Rabbit's Intestinal Mucous Membrane

Vertical section of the intestinal mucous membrane of the rabbit. Two villi are represented, in one…

"Cross-section of prismatic reflector, showing how light rays are refracted and dispersed." —Croft 1917

Prismatic Reflector

"Cross-section of prismatic reflector, showing how light rays are refracted and dispersed." —Croft…

A cross-section of a turn of the cochlea of the ear(diagrammatic).

Cochlea of the Ear

A cross-section of a turn of the cochlea of the ear(diagrammatic).

"From a cross piece, A, on a stout framework, a heavy block of wood, B, is suspended, in such a way as to move freely backward and forward. A ball fired into this block will drive it back to a distance proportioned to the ball's velocity. All other things being known, the ball's velocity can be discovered." —Quackenbos 1859

Ballistic Pendulum

"From a cross piece, A, on a stout framework, a heavy block of wood, B, is suspended, in such a way…

Cross section of pipe, 2 concentric circles

Cross Section of Pipe

Cross section of pipe, 2 concentric circles

Machine screw diagram

Machine Screw

Machine screw diagram

Machine screw diagram

Machine Screw

Machine screw diagram

Machine screw diagram

Machine Screw

Machine screw diagram

Machine screw diagram

Machine Screw

Machine screw diagram

Cross section of road that can be used to find area of composite figures.

Cross Section of Road

Cross section of road that can be used to find area of composite figures.

Cross section of steel beam that can be used to find area of composite figures.

Cross Section of Beam

Cross section of steel beam that can be used to find area of composite figures.

Cross section of concrete conduit. The diagram can be used to find volume.

Cross Section of Concrete Conduit

Cross section of concrete conduit. The diagram can be used to find volume.

Cross section of Pullman car water tank. The diagram can be used to find volume.

Cross Section of Water Tank

Cross section of Pullman car water tank. The diagram can be used to find volume.

Cylindrical water tank with a height of 10 ft., thickness of 3 inches, and diameter of 3 feet. The diagram can be used to find volume.

Cylindrical Water Tank

Cylindrical water tank with a height of 10 ft., thickness of 3 inches, and diameter of 3 feet. The diagram…

An illustration of a vertical cross section of the spherical zones of a casting with a diameter of 16 inches.

Vertical Cross Section of Spherical Zones of a Casting

An illustration of a vertical cross section of the spherical zones of a casting with a diameter of 16…

An illustration of a cross section of a concrete pier for a railway bridge with dimensions labeled. Illustration could be used to calculate volume and area of figures.

Cross Section of Concrete Pier for Railway bridge

An illustration of a cross section of a concrete pier for a railway bridge with dimensions labeled.…

Right triangle ABC with angles A, B, C to be used for finding distance across a river. This is a trigonometry problem. Wishing to determine the width of the river, I observed a tree standing directly across on the bank. The angle of elevation of the top of the tree was 32 degrees. At 150 ft. back from this point and in the same direction from the tree the angle of elevation of the top of the tree was 21 degrees. Find the width of the river.

Right Triangle For Finding Distance Across a River

Right triangle ABC with angles A, B, C to be used for finding distance across a river. This is a trigonometry…

Diagrams of spinal cord and nerve roots. Labels: A, a small portion of the cord seen from the ventral side; B, the same seen laterally; C, a cross-section of the cord; D, the two roots of a spinal nerve; 1, anterior (ventral) fissure; 2, posterior (dorsal) fissure; 3, surface groove along the line of attachment of the anterior nerve roots; 4, line of origin of the posterior roots; 5, anterior root filaments of a spinal nerve; 6, posterior root filaments; 6', ganglion of the posterior root; 7, 7', the first two divisions of the nerve trunk after its formation by the union of the two roots.

Spinal Cord and Nerve Roots

Diagrams of spinal cord and nerve roots. Labels: A, a small portion of the cord seen from the ventral…

Section of skin showing two papillae of the dermis and some of the deeper cells of the epidermis, involved in sensation of the skin. Labels: a, papilla containing blood vessels; b, papilla containing a tactile corpuscle, t; d, medullated nerve fibers going to the corpuscle; at f, optical cross-sections of the fibers are seen as they wind round the outside of the corpuscle; the general transverse direction of the connective tissue bundles of the capsule of the corpuscle is shown.

Sensation of the Skin

Section of skin showing two papillae of the dermis and some of the deeper cells of the epidermis, involved…

Geometric pattern for translation and rotation exercises.

Geometric Block Pattern 101

Geometric pattern for translation and rotation exercises.

Cross-section of the external and internal ear. <em>a, b, and c</em>: External ear. <em>d</em>: Entrance to the tube of the ear <em>(f)</em>. <em>g</em>: Drum of the ear. <em>h</em>: Cavity beyond the drum where the chain of bones is, the bones being left out that the arrangement of the apparatus may be more clear to you. <em>k</em>: Tube which comes from the back part of the throat to this cavity. If you shut your mouth and close the nostrils with your fingers, and then force the air strongly from your chest into the mouth, you can feel the air pass through this tube into the ear where the little bones are. <em>l</em>: is the vestibule of the labyrinth. <em>m</em>: Semi-circular canals. <em>n</em>: Cochlea. <em>o</em>: Trunk of the nerve of hearing as it goes to branch out in the labyrinth. <em>e</em>: Bone in which the labyrinth is enclosed.

A Cross-Section of the Ear

Cross-section of the external and internal ear. a, b, and c: External ear. d: Entrance…

A grid with the corners of each square marked by cross shapes.

Cross Grid

A grid with the corners of each square marked by cross shapes.

A grid with the corners of each square marked by cross shapes.

Cross Grid

A grid with the corners of each square marked by cross shapes.

Cross-section of the brain. Here the upper half of the brain is cut off, and you see the upper cut surface of the lower half. The outer shaded part is the gray matter, and the inner lighter area is the white matter. In the center is the corpus callosum, a type of white matter that connects the two hemispheres together.

Cross-Section of the Brain

Cross-section of the brain. Here the upper half of the brain is cut off, and you see the upper cut surface…

Illustration of a frustum of a hexagonal pyramid (including cross-section).

Frustum of Hexagonal Pyramid

Illustration of a frustum of a hexagonal pyramid (including cross-section).

Illustration of a frustum of a pentagonal pyramid (including cross-section).

Frustum of Pentagonal Pyramid

Illustration of a frustum of a pentagonal pyramid (including cross-section).

The spinal cord and medulla oblongata. Labels: A, from the ventral, and B, from the dorsal aspect; C to H, cross-sections at different levels.

The Spinal Cord and Medulla Oblongata

The spinal cord and medulla oblongata. Labels: A, from the ventral, and B, from the dorsal aspect; C…

Leaves - simple; alternate; edge sharply and often doubly toothed. Outline - oval or egg-shaped, or inversely egg-shaped; always one-sided. Apex - taper-pointed. Base - rounded, or slightly heart-shaped, rarely pointed. Leaf/Stem - about one quarter inch long. Buds - smooth. Leaf - usually two to five inches long, and one and a half to two and a half wide; somewhat downy when young, afterward roughish below; above, either rough in one direction, or (especially if taken from the ends of the long branches) smooth and shining. Ribs - prominent and straight. Bark - of the branches not marked with "corky ridges"; branchlets, smooth. Seeds - flat egg-shaped or oval, winged and fringed all around. Last of May. Found - northward to Southern Newfoundland; southward to Florida; westward to the Black Hills of Dakota. Toward the western and southwestern limits it is found only in the river-bottom lands. General Information - One of the very noblest of American trees, eighty feet or more in height, and of strong and graceful proportions. The trunk divides at a slight angle into two or three arching limbs, and these again into many smaller curving and drooping branches. The trunk and the larger branches are often heavily fringed with short and leafy boughs. The tree is widely cultivated. Streets planted with it become columned and arched like the aisles of a Gothic cathedral. The wood is hard, and very tough from the interlacing of its fibers. It is used in making saddle-trees and for wheel-hubs, and is now largely exported to England to be used in boat- and ship-building. One day I found four men in a stone quarry, working with iron bars and rollers over a heavy flat slab. They were moving the stone slowly up a narrow plant into their cart. "John, " I said, "I would not think that board could hold a stone of such weight two minutes. Is it hickory?" "No sir, " said John, " that's an elm plank; it can't break." It did not break. It was one of the woods which the Deacon used in building his famous "one-hoss shay": So the deacon inquired of the village folk Where he could find the strongest oak, That count n't be split nor bent nor broke, - That was for spokes and floor and sills; He sent for lancewood to make the thills; The cross-bars were ash, from the straightest trees; The panels of whitewood, that cuts like cheese, But lasts like iron for thing like these; The hubs of logs from the Settler's Ellum; - Last of its timber, - they could n't sell 'em, Never an axe had seen their chips, And the wedges flew from between their lips, Their blunt ends frizzled like celery-tips;" --Oliver Wendell Holmes

Genus Ulmus, L. (Elm)

Leaves - simple; alternate; edge sharply and often doubly toothed. Outline - oval or egg-shaped, or…

Leaves - simple; alternate; edge very sharply and slightly irregularly and unequally toothed. Outline - long oval or long egg-shape. Apex - taper-pointed. Base - slightly heart-shaped. Leaf/Stem - about one fourth inch long, and often rough. Leaf - usually three to four inches long, and about half as wide, but with many smaller leaves of varying size on the same branch; smoothish above, paler and somewhat downy below. Ribs - The straight ribs and their angles hairy. Bark - of trunk, brownish or dark gray, and remarkable for being finely furrowed up and down, with the ridges broken into three - to four-inch lengths. These divisions are narrower than on any other rough-barked tree, and they become narrower and finer as the tree grows older. The new shoots are reddish green and dotted with brown; the younger branches purplish-brown and dotted with white or gray. When the branch is two to three inches thick, its bark becomes grayish and begins to crack. Fruit - in long oval, drooping clusters, resembling those of the hop-vine, with long, unlobed scales that lap each other like shingles. August, September. Found - oftenest on dry hill-sides. Common North, South, and West, especially in Southern Arkansas. General Information - A tree twenty to thirty feet high, with white, very strong, and compact wood. It would be very valuable, if it were more abundant and of larger growth.

Genus ostrya, Scop. (Hop-Hornbeam)

Leaves - simple; alternate; edge very sharply and slightly irregularly and unequally toothed. Outline…

Leaves - simple; alternate; edge sharp-toothed, with rounded hollows between. Outline - rounded. Apex - short, sharp-pointed. Base - slightly heart-shaped. Leaf/Stem - slender and very much flattened sidewise. Leaf - two to two and a half inches wide, and usually about one half inch shorter than wide; dark green; smooth on both sides when mature, with a slight down on the edge. Ribs distinct above and below and whitish. Bark - of trunk, greenish-white and smooth, often with blotches of very dark brown, especially under the ends of the branches. The bark is exceedingly bitter. Found - from Northern Kentucky and the mountains of Pennsylvania northward to Hudson Bay and Newfoundland, northwest to the Arctic Ocean, and along the Rocky Mountain slopes. It is the most widely distributed of North American Trees. General Information - A tree twenty to fifty feet high, with white, soft wood that is largely used in place of rags in making coarse paper. The tremulousness of its foliage, which the slightest breeze stirs, is due to the thinness of the sidewise-flattened leaf-stems. Tradition accounts differently for the motion of the leaves. It says that the wood of the aspen tree was taken for the Saviour's cross, and that, ever since, the tree has shivered. Another tradition claims that, when Christ went by on his way to Calvary, all the trees sympathized and mourned, excepting the aspen; but when he died, there fell upon the aspen a sudden horror of remorse, and such a fearful trembling as has never passed away. In describing the occupations of the fifty maidens in the hall of the "gorgeous palace" of King Alcinous, Homer says: "...some wove the web, Or twirled the spindle, sitting, with a quick, Light motion like the aspen's glancing leaves."

Genus Populus, L. (Aspen, Poplar)

Leaves - simple; alternate; edge sharp-toothed, with rounded hollows between. Outline - rounded. Apex…

A large tree atop a hillside near a fence and birds flying by.

Tree

A large tree atop a hillside near a fence and birds flying by.