Illustration showing a parabola as a curve formed by the intersection of the surface of a cone with a plane parallel to a straight line of the surface of the cone.

Parabola

Illustration showing a parabola as a curve formed by the intersection of the surface of a cone with…

Diagram of a cone intersected by plane J to form a parabola. Also pictured is a circle formed by the intersection of plane K with the cone. "Every point of a parabola is equidistant from the focus and the directrix."

Cone Intersected by a Plane to Form a Parabola

Diagram of a cone intersected by plane J to form a parabola. Also pictured is a circle formed by the…

Illustration showing the definition of a parabola as a conic section. The plane cuts the cone parallel to one element.

Conic Section Showing Parabola

Illustration showing the definition of a parabola as a conic section. The plane cuts the cone parallel…

Illustration showing the definition of a parabola as a conic section. The section of a right circular cone made by a plane parallel to one, and only one, element of the surface is a parabola.

Conic Section Showing A Parabola

Illustration showing the definition of a parabola 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 a side. Thus forming a parabola.

Conic Section Showing A Parabola

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

Diagram showing how to construct a parabola when given the directrix (d), the focus (F) and the eccentricity (m).

Construction of a Parabola

Diagram showing how to construct a parabola when given the directrix (d), the focus (F) and the eccentricity…

Also known as Pinus quadrifolia. The pine cone of a Parry Pinyon tree.

Pine Cone of a Parry Pinyon

Also known as Pinus quadrifolia. The pine cone of a Parry Pinyon tree.

The pine cone of a Picea parryana pine tree.

Picea Parryana Pine Cone

The pine cone of a Picea parryana pine tree.

There are many species of pine trees, distinguished by their types of cones.

Pine

There are many species of pine trees, distinguished by their types of cones.

There are many species of pine trees, distinguished by their types of cones.

Pine

There are many species of pine trees, distinguished by their types of cones.

A pine cone of a Pinus aristata.

Pine Cone of Pinus Aristata

A pine cone of a Pinus aristata.

The cones of pinus coulteri are very large, about twelve inches long and six inches in diameter. The cones weigh between four and five pounds.

Cone of Pinus Coulteri

The cones of pinus coulteri are very large, about twelve inches long and six inches in diameter. The…

The pine cone of a Pinus sabiniana.

Pine Cone of Pinus Sabiniana

The pine cone of a Pinus sabiniana.

Also known as Pinus rigida. The pine cone of a Pitch Pine tree.

Pine Cone of Pitch Pine

Also known as Pinus rigida. The pine cone of a Pitch Pine tree.

Also known as Abies magnifica. Native to the mountains of western North America.

Pine Cone of Red Fir

Also known as Abies magnifica. Native to the mountains of western North America.

Also known as Pinus resinosa. The pine cone of a Red Pine tree.

Pine Cone of Red Pine

Also known as Pinus resinosa. The pine cone of a Red Pine tree.

Also known as Picea rubens. Native to North America.

Red Spruce Pine Cone

Also known as Picea rubens. Native to North America.

Also known as Sequoia sempervirens. An evergreen monoecious tree living between 1200-1800 years or more.

Pine Cone of Redwood

Also known as Sequoia sempervirens. An evergreen monoecious tree living between 1200-1800 years or more.

Perpendicular section of mammalian retina. Labels: A, layer of rods and cones; B, outer nuclear layer; C, outer molecular layer; D, inner nuclear layer; E, inner molecular layer; F, ganglionic layer; G, stratum opticum; r, rods; c, cones, r.g, rod granules; c.g, cone granules; r.b, rod bipolars; c.b, cone bipolars; c.r, vontact of rod bipolars with the internal arborisation of cone bipolars; ar', internal arborisation of rod bipolars; c.n, centrifugal nerve fiber; h, horizontal cells; s.s, stratified spongioblasts; d.s, diffuse spongioblasts; s.g, stratified ganglion cell; M, sustentacular fiber of Muller.

Section of Retina

Perpendicular section of mammalian retina. Labels: A, layer of rods and cones; B, outer nuclear layer;…

Also known as Abies lasiocarpa. A western North American fir.

Pine Cone of Rocky Mountain Fir

Also known as Abies lasiocarpa. A western North American fir.

Cycas revoluta or sago cycad is known as the king sago palm but is not a palm; it is a cycad.

Sago Cycad

Cycas revoluta or sago cycad is known as the king sago palm but is not a palm; it is a cycad.

Each scale of the pine cone is a whole pistillate flower. (Gray, 1858).

Scale

Each scale of the pine cone is a whole pistillate flower. (Gray, 1858).

Each scale of the pine cone is a whole pistillate flower. (Gray, 1858).

Scale

Each scale of the pine cone is a whole pistillate flower. (Gray, 1858).

A variety of leaves with scales: "a, the scale-like leaves of the stem of Lathraea squamaria (toothwort); b, the cone with the scales of Cupressus sempervirens (Mediterranean Cypress); c, the imbricate scale-like bract of the spike of Cyperus longus (common galingale)." -Whitney, 1911

Scaled Leaves

A variety of leaves with scales: "a, the scale-like leaves of the stem of Lathraea squamaria (toothwort);…

Also known as Pinus sylvestris. This image depicts the branchlet and cones of the Scots Pine.

Scots Pine

Also known as Pinus sylvestris. This image depicts the branchlet and cones of the Scots Pine.

Also known as Pinus sylvestris. The cones of this tree have a dense hue, and are between 1.5 inches to 2 inches in length.

Cone of the Scots Pine

Also known as Pinus sylvestris. The cones of this tree have a dense hue, and are between 1.5 inches…

Also known as Abies magnifica var. shastensis.

Pine Cone of Shasta Red Fir

Also known as Abies magnifica var. shastensis.

Also known as Pinus echinata. The pine cone of a Shortleaf Pine tree.

Pine Cone of Shortleaf Pine

Also known as Pinus echinata. The pine cone of a Shortleaf Pine tree.

Also known as Albies alba.

Pine Cone of Silver Fir

Also known as Albies alba.

Also known as Pinus monophylla. The pine cone of a Single-leaf Pinyon.

Pine Cone of Single-Leaf Pinyon

Also known as Pinus monophylla. The pine cone of a Single-leaf Pinyon.

Also known as Picea sitchensis. The pine cone of the largest species of spruce trees.

Sitka Spruce Pine Cone

Also known as Picea sitchensis. The pine cone of the largest species of spruce trees.

Illustration showing the development of a sphere by the perspective of its resolved cones.

Development Of Sphere

Illustration showing the development of a sphere by the perspective of its resolved cones.

An illustration of the spruce fir's cone, and foliage.

Spruce Fir Cone and Foliage

An illustration of the spruce fir's cone, and foliage.

Also known as Pinus glabra. The pine cone of a Spruce Pine tree.

Pine Cone of Spruce Pine

Also known as Pinus glabra. The pine cone of a Spruce Pine tree.

Also known as Pinus lamertiana. The pine cone of a sugar pine tree.

Pine Cone of Sugar Pine

Also known as Pinus lamertiana. The pine cone of a sugar pine tree.

Also known as Pinus pungens. The Table Mountain Pine is native to the Appalachian Mountains.

Table Mountain Pine Cone

Also known as Pinus pungens. The Table Mountain Pine is native to the Appalachian Mountains.

Also known as Larix americana. The pine cone of a Tamarack Larch tree.

Tamarack Larch Pine Cone

Also known as Larix americana. The pine cone of a Tamarack Larch tree.

Also known as Pinus contorta, var. murrayana. The pine cone of a Tamarack Pine tree, native to the Cascade Range, Sierra Nevada, and surrounding mountain ranges.

Pine Cone of Tamarack Pine

Also known as Pinus contorta, var. murrayana. The pine cone of a Tamarack Pine tree, native to the Cascade…

Also known as Pinus torreyana. The Torrey Pine is the rarest pine species in the United States, and is generally found on the West Coast.

Torrey Pine Cone

Also known as Pinus torreyana. The Torrey Pine is the rarest pine species in the United States, and…

Illustration showing intersecting straight lines meeting to form a triangle. It is formed by the intersection of the surface of a cone with a plane parallel to the axis and actually containing the axis.

Degenerate Conic Forming Triangle

Illustration showing intersecting straight lines meeting to form a triangle. It is formed by the intersection…

The most interesting monuments of Etruscan architecture which have been preserved are the tombs. They are for the most part chambers hewn in the rock, and supported by square piers. The tombs were either subterranean, and had an entrance façade hewn out of the rock, or they assume the shape of tumuli, which had one or more conical elevations resting on a superstructure.

Tumuli

The most interesting monuments of Etruscan architecture which have been preserved are the tombs. They…

"The cone B would be developed by cutting a right section as S—S whose stretchout will be a circle are, location the elements on it and finding the true length of each from the vertex to the line of intersection." —French, 1911

Intersection of Two Cones

"The cone B would be developed by cutting a right section as S—S whose stretchout will be a circle…

Also known as Pinus virginiana.

Virginia Pine, Pine Cone

Also known as Pinus virginiana.

An experimental illustration of the mode of formation of volcanic blister cones composed of viscid lavas.

Volcanic Blister Cone

An experimental illustration of the mode of formation of volcanic blister cones composed of viscid lavas.

Also known as Tsuga heterophylla. A species of hemlock native to the west coast of North America.

Pine Cone of Western Hemlock

Also known as Tsuga heterophylla. A species of hemlock native to the west coast of North America.

Also known as Larix occidentalis. A species of larch native to the mountains of western North America.

Western Larch Pine Cone

Also known as Larix occidentalis. A species of larch native to the mountains of western North America.

Also known as Thuja plicata. An evergreen coniferous tree native to western North America.

Branch of Western Redcedar

Also known as Thuja plicata. An evergreen coniferous tree native to western North America.

Also known as Pinus monticola. A pine cone of the Western White Pine tree.

Pine Cone of Western White Pine

Also known as Pinus monticola. A pine cone of the Western White Pine tree.

Also known as Abies concolor. Native to the mountains of western North America.

Pine Cone of White Fir

Also known as Abies concolor. Native to the mountains of western North America.

Also known as Picea glauca. A spruce tree native to the northern half of North America.

White Spruce Pine Cone

Also known as Picea glauca. A spruce tree native to the northern half of North America.

Also known as Pinus albicaulis. A pine cone from a Whitebark Pine tree.

Pine Cone of Whitebark Pine

Also known as Pinus albicaulis. A pine cone from a Whitebark Pine tree.