"The spinal column below the twelfth dorsal vertebra at <em>A</em> has been removed, as well as the various layers of the great muscles of the back. The two kidneys with the renal arteries and veins are plainly shown, in their normal positions. The relative positions of adjacent vessels and organs with their names printed upon them are also shown. <em>B</em>, portion of the diaphragm on the left side; <em>C</em>, receptaculum chyli; <em>D</em>, a part of the small intestine on the left side." &mdash; Blaisedell, 1904

Vertical section of the back

"The spinal column below the twelfth dorsal vertebra at A has been removed, as well as the…

"1. fruit of Brexia madagascariensis; 2. a cross section of it; 3. a seed; 4. the same divided perpendicularly." -Lindley, 1853

Brexia

"1. fruit of Brexia madagascariensis; 2. a cross section of it; 3. a seed; 4. the same divided perpendicularly."…

"Cascade Furnace&mdash;Longitudinal Section." &mdash; The Encyclopedia Britannica, 1893

Cascade Furnace

"Cascade Furnace—Longitudinal Section." — The Encyclopedia Britannica, 1893

"Gastrula of a Chalk-sponge (Olynthus). B, longitudinal section through the axis: g, primitive intestine; o, blastopore; i, inner cell-layer of the body-wall; e, outer cell-layer." -Whitney, 1911

Chalk Sponge Gastrula

"Gastrula of a Chalk-sponge (Olynthus). B, longitudinal section through the axis: g, primitive intestine;…

"Drupe. b, stony wall of the putamen, inclosing the seed." -Whitney, 1911

Cherry Section

"Drupe. b, stony wall of the putamen, inclosing the seed." -Whitney, 1911

Illustration showing the definition of a circle as a conic section. The section of a right circular cone made by a plane that is perpendicular to the axis (or parallel to the base).

Conic Section Showing A Circle

Illustration showing the definition of a circle as a conic section. The section of a right circular…

An illustration showing the intersection of a plane and a cone. The cone is intersected by a plane parallel to the base, forming a circle.

Conic Section Showing A Circle

An illustration showing the intersection of a plane and a cone. The cone is intersected by a plane parallel…

Illustration showing a cone cut by a plane that is along the axis of symmetry.

Plane Passing Through A Cone

Illustration showing a cone cut by a plane that is along the axis of symmetry.

The Basilica di Santa Maria del Fiore is the cathedral church (Duomo) of Florence, Italy, begun in 1296 and with major construction completed in 1436. The basilica is notable for its dome designed by Filippo Brunelleschi, its exterior facing of polychrome marble panels in various shades of green and pink bordered by white.

Section of the Dome of Duomo, Florence

The Basilica di Santa Maria del Fiore is the cathedral church (Duomo) of Florence, Italy, begun in 1296…

The Elisabeth Church in Marburg was built by the Order of the Teutonic Knights in honor of Elisabeth of Hungary. Her tomb made the church an important pilgrimage destination in the late Middle Ages. The building is now a Protestant church.

Section of Elisabeth Church, Marburg, Germany

The Elisabeth Church in Marburg was built by the Order of the Teutonic Knights in honor of Elisabeth…

Illustration of half of an ellipse. "The ordinates of two corresponding points in an ellipse and its auxiliary circle are in the ratio b:a."

Corresponding Points in an Ellipse and Circle

Illustration of half of an ellipse. "The ordinates of two corresponding points in an ellipse and its…

Illustration of half of an ellipse used to show that the area of an ellipse is equal to pi times a times b.

Area of an Ellipse

Illustration of half of an ellipse used to show that the area of an ellipse is equal to pi times a times…

Illustration showing the definition of an ellipse as a conic section. "The section of a right circular cone made by a plane that cuts all the elements of the surface of the cone is an ellipse."

Conic Section Showing an Ellipse

Illustration showing the definition of an ellipse as a conic section. "The section of a right circular…

Illustration showing the definition of an ellipse as a conic section. "The section of a right circular cone made by a plane that cuts all the elements of the surface of the cone is an ellipse."

Conic Section Showing an Ellipse

Illustration showing the definition of an ellipse as a conic section. "The section of a right circular…

Illustration showing the definition of an ellipse as a conic section. The section of a right circular cone made by a plane that cuts all the elements of the surface of the cone is an ellipse. The plane is neither parallel nor perpendicular to the axis.

Conic Section Showing An Ellipse

Illustration showing the definition of an ellipse as a conic section. The section of a right circular…

An illustration showing the intersection of a plane and a cone. The cone is intersected by a plane neither parallel to nor perpendicular to the base, nor parallel to a side. Thus forming an ellipse.

Conic Section Showing An Ellipse

An illustration showing the intersection of a plane and a cone. The cone is intersected by a plane neither…

Illustration showing that if one diameter is conjugate to a second, the second is conjugate to the first.

Conjugate Diameters of an Ellipse

Illustration showing that if one diameter is conjugate to a second, the second is conjugate to the first.

Illustration of half of an ellipse and its auxiliary circle used to construct an ellipse by points, having given its two axes.

Construction of an Ellipse

Illustration of half of an ellipse and its auxiliary circle used to construct an ellipse by points,…

Illustration used to show how to draw an ellipse when given the diameters.

Construction Of Ellipse

Illustration used to show how to draw an ellipse when given the diameters.

Illustration used to show how to draw an ellipse by circular arcs.

Construction Of Ellipse

Illustration used to show how to draw an ellipse by circular arcs.

Illustration showing the definition of an ellipse. "An ellipse is a curve which is the locus of a point that moves in a plane so that the sum of its distances from two fixed points in the plane is constant." The foci and major axis is drawn.

Demonstration of Ellipse Definition

Illustration showing the definition of an ellipse. "An ellipse is a curve which is the locus of a point…

Illustration of half of an ellipse. "If d denotes the abscissa of a point of an ellipse, r and r' its focal radii, then r'=a+ed, r=a-ed."

Focal Radii of an Ellipse

Illustration of half of an ellipse. "If d denotes the abscissa of a point of an ellipse, r and r' its…

Illustration of an ellipse with foci F' and F, major axis A' to A, minor axis B' to B, and center O.

Ellipse With Parts Labeled

Illustration of an ellipse with foci F' and F, major axis A' to A, minor axis B' to B, and center O.

Illustration of half of an ellipse. "If through a point P of an ellipse a line is drawn bisecting the angle between one of the focal radii and the other produced, every point in this line except P is without the curve."

Line Bisecting Angle Between Focal Radii on Ellipse

Illustration of half of an ellipse. "If through a point P of an ellipse a line is drawn bisecting the…

Illustration of half of an ellipse. The square of the ordinate of a point in an ellipse is to the product of the segments of the major axis made by the ordinate as the square of b to the square of a.

Ordinate and Major Axis of Ellipse

Illustration of half of an ellipse. The square of the ordinate of a point in an ellipse is to the product…

Illustration showing that tangents drawn at the ends of any diameter are parallel to each other.

Parallel Tangents to an Ellipse

Illustration showing that tangents drawn at the ends of any diameter are parallel to each other.

Illustration of half of an ellipse. "The sum of the distances of any point from the foci of an ellipse is greater than or less than 2a, according as the point is without or within the curve."

Point Distances to Foci on Ellipse

Illustration of half of an ellipse. "The sum of the distances of any point from the foci of an ellipse…

Illustration of how to draw a tangent to an ellipse from an external point.

Tangent From External Point to an Ellipse

Illustration of how to draw a tangent to an ellipse from an external point.

Illustration showing the tangents drawn at two corresponding points of an ellipse and its auxiliary circle cut the major axis produced at the same point.

Tangents to an Ellipse

Illustration showing the tangents drawn at two corresponding points of an ellipse and its auxiliary…

Transverse section of the great ore chamber in the Emma mine, Utah.

Emma mine, Utah

Transverse section of the great ore chamber in the Emma mine, Utah.

"Section of the human eye." &mdash; Blaisedell, 1904

Human eye

"Section of the human eye." — Blaisedell, 1904

The fruit from a fig tree (Ficus carica) showing its section.

Section of Fruit of Fig

The fruit from a fig tree (Ficus carica) showing its section.

"Section of Fortified Wall. (Interior on the left; exterior on the right.) a, a, is the abatis; b, b, the counterscarp; c, c, the palisade; d, d, the scarp; f, f, the fraise; f, e, g, g, the parapet; h, the banquette; and i, g, the breast-height." -Whitney, 1911

Section of Fortified Wall

"Section of Fortified Wall. (Interior on the left; exterior on the right.) a, a, is the abatis; b, b,…

"Gjers's Furnace Hoist. I. Section. II. Elevation. III. and IV. Plans." &mdash; The Encyclopedia Britannica, 1893

Furnace Hoist

"Gjers's Furnace Hoist. I. Section. II. Elevation. III. and IV. Plans." — The Encyclopedia Britannica,…

"Section of Gas-holder." &mdash; Encyclopedia Britannica, 1893

Gas-holder

"Section of Gas-holder." — Encyclopedia Britannica, 1893

An section illustration of the Great Pyramid.

Great Pyramid Section

An section illustration of the Great Pyramid.

A gyroscope that is rotated to form an ellipse.

Gyroscope

A gyroscope that is rotated to form an ellipse.

"Longitudinal section of a Hydra; <em>b</em>, bud which will form a young one; <em>ba</em>, base by which it is attached when not creeping." &mdash; Davison, 1906

Section of a hydra

"Longitudinal section of a Hydra; b, bud which will form a young one; ba, base by…

Illustration showing the asymptotes of a hyperbola. The asymptotes will never meet the curve.

Asymptotes of a Hyperbola

Illustration showing the asymptotes of a hyperbola. The asymptotes will never meet the curve.

Illustration of a hyperbola and its auxiliary circle. "Any ordinate of a hyperbola is to the tangent from its foot to the auxiliary circle as b is to a."

Auxiliary Circle and Hyperbola

Illustration of a hyperbola and its auxiliary circle. "Any ordinate of a hyperbola is to the tangent…

Illustration showing the definition of an hyperbola as a conic section. "The section of a right circular cone made by a plane that cuts both nappes of the cone is a hyperbola." A double right circular cone with a plane parallel to the axis cutting through the cones.

Conic Section Showing an Hyperbola

Illustration showing the definition of an hyperbola as a conic section. "The section of a right circular…

Illustration showing the definition of an hyperbola as a conic section. A hyperbola is formed from a double right circular cone with a plane parallel to the axis cutting through the cones.

Conic Section Showing A Hyperbola

Illustration showing the definition of an hyperbola as a conic section. A hyperbola is formed from a…

An illustration showing the intersection of a plane and a double cone. The cone is intersected by a plane parallel to the axis. Thus forming a Hyperbola.

Conic Section Showing A Hyperbola

An illustration showing the intersection of a plane and a double cone. The cone is intersected by a…

Illustration showing how the a hyperbola is symmetrical with respect to its conjugate axis.

Conjugate Axis of a Hyperbola

Illustration showing how the a hyperbola is symmetrical with respect to its conjugate axis.

Illustration showing how a hyperbola con be constructed by points, having been given the foci and the constant difference 2a.

Construction of Hyperbola

Illustration showing how a hyperbola con be constructed by points, having been given the foci and the…

Illustration showing the definition of an hyperbola. "An hyperbola may be described by the continuous motion of a point, as follows: To one of the foci F' fasten one end of a rigid bar F'B so that it is capable of turning freely about F' as a center in the plane of the paper."

Demonstration of Hyperbola Definition

Illustration showing the definition of an hyperbola. "An hyperbola may be described by the continuous…

Illustration of a hyperbola with distances to foci drawn. "The difference of the distances of any point from the foci of an hyperbola is greater than or less than 2a, according as the point is on the concave or convex side of the curve."

Foci Distance of Hyperbola

Illustration of a hyperbola with distances to foci drawn. "The difference of the distances of any point…

Illustration of a hyperbola with a line bisecting the focal radii. "If through a point P of an hyperbola a line is drawn bisecting the angle between the focal radii, every point in this line except P is on the convex side of the curve.

Line Bisecting Angle Between Focal Radii in Hyperbola

Illustration of a hyperbola with a line bisecting the focal radii. "If through a point P of an hyperbola…

Illustration of a point on a hyperbola. "If d denotes the abscissa (x-coordinate) of a point of an hyperbola, r and r' its focal radii, then r = ed - a, and r' = ed + a."

Point on a Hyperbola

Illustration of a point on a hyperbola. "If d denotes the abscissa (x-coordinate) of a point of an hyperbola,…

Illustration showing how to draw a tangent to an hyperbola from a given point P on the convex side of the hyperbola.

Tangent to Hyperbola

Illustration showing how to draw a tangent to an hyperbola from a given point P on the convex side of…

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…

"Lapidary's Dial. A, section; B, side elevation; a, a, jaws; b, ball; c, tube; d, dial; e, cement rod; f, index; g, quadrant." &mdash;The Encyclopedia Britannica, 1910

Lapidary's dial

"Lapidary's Dial. A, section; B, side elevation; a, a, jaws; b, ball; c, tube; d, dial; e, cement rod;…

Ideal section through a Maar of the Eifel showing the old crater funnel and pipe.

Maar of the Eifel

Ideal section through a Maar of the Eifel showing the old crater funnel and pipe.

The magic circle of circles, first developed by Benjamin Franklin, consists of eight annular rings and a central circle, each ring being divided into eight cells by radii drawn from the centre; there are therefore 65 cells. The number 12 is placed in he center and the consecutive numbers 13 to 75 are placed in the other cells. The properties are: 1) sum of eight numbers in any ring with 2 equals 360, 2) sum of eight numbers in any set of radial rings with 12 is 360, 3) sum of numbers in any four adjoining cells is 180.

Magic Circle of Circles

The magic circle of circles, first developed by Benjamin Franklin, consists of eight annular rings and…

Section of the massif of Mont Dore, France, showing the succession of eruptions and the outline of the old volcano.

Mont Dore, France

Section of the massif of Mont Dore, France, showing the succession of eruptions and the outline of the…

Section of frontal moraine on side of Warner Street, Glouchester, Massachusetts.

Section of Frontal Moraine

Section of frontal moraine on side of Warner Street, Glouchester, Massachusetts.

Section of the Mt. Holmes bysmalith.

Mt. Holmes Bysmalith

Section of the Mt. Holmes bysmalith.

The modern Pearly Nautilus; the animal occupies the living chamber of the sectioned shell.

Chambered Nautilus

The modern Pearly Nautilus; the animal occupies the living chamber of the sectioned shell.

"It was in Central France, and mainly along the Loire, that the systematic development of vaulted church architecture began. Naves covered with barrel-vaults, sometimes of pointed section, appear in a number of large churches built during the eleventh and twelfth centuries, with apsidal and transeptal chapels and aisles carried around the apse, as in Notre-Dame du Port at Clermont-Ferrand. The thrust of these ponderous vaults was clumsily resisted by half-barrel vaults over the side aisles, transmitting the strain to massive side-walls."

Section of Notre-Dame du Port

"It was in Central France, and mainly along the Loire, that the systematic development of vaulted church…

"Flowering Branch of Oleaster (Elaeagnus angustifolia). a, fruit; b, section of same." -Whitney, 1911

Oleaster

"Flowering Branch of Oleaster (Elaeagnus angustifolia). a, fruit; b, section of same." -Whitney, 1911