Illustration of an elongated square dipyramid that is formed by elongating a square bipyramid by inserting a square prism between the two congruent halves. The elongated dipyramid pictured here is tilted, or rotated, approximately 45°.

Elongated Square Dipyramid

Illustration of an elongated square dipyramid that is formed by elongating a square bipyramid by inserting…

Illustration of an elongated nonagonal dipyramid that is formed by elongating a nonagonal bipyramid by inserting a nonagonal prism between the two congruent halves.

Elongated Nonagonal Dipyramid

Illustration of an elongated nonagonal dipyramid that is formed by elongating a nonagonal bipyramid…

Illustration of an elongated nonagonal dipyramid that is formed by elongating a nonagonal bipyramid by inserting a nonagonal prism between the two congruent halves.

Elongated Nonagonal Dipyramid

Illustration of an elongated nonagonal dipyramid that is formed by elongating a nonagonal bipyramid…

Illustration of an elongated hexagonal dipyramid that is formed by elongating a hexagonal bipyramid by inserting a hexagonal prism between the two congruent halves.

Elongated Hexagonal Dipyramid

Illustration of an elongated hexagonal dipyramid that is formed by elongating a hexagonal bipyramid…

Illustration of an elongated hexagonal dipyramid that is formed by elongating a hexagonal bipyramid by inserting a hexagonal prism between the two congruent halves.

Elongated Hexagonal Dipyramid

Illustration of an elongated hexagonal dipyramid that is formed by elongating a hexagonal bipyramid…

Illustration of an elongated hexagonal dipyramid that is formed by elongating a hexagonal bipyramid by inserting a hexagonal prism between the two congruent halves.

Elongated Hexagonal Dipyramid

Illustration of an elongated hexagonal dipyramid that is formed by elongating a hexagonal bipyramid…

Illustration of an elongated heptagonal/septagonal dipyramid that is formed by elongating a heptagonal bipyramid by inserting a heptagonal prism between the two congruent halves.

Elongated Heptagonal/Septagonal Dipyramid

Illustration of an elongated heptagonal/septagonal dipyramid that is formed by elongating a heptagonal…

Illustration of an elongated heptagonal/septagonal dipyramid that is formed by elongating a heptagonal bipyramid by inserting a heptagonal prism between the two congruent halves.

Elongated Heptagonal/Septagonal Dipyramid

Illustration of an elongated heptagonal/septagonal dipyramid that is formed by elongating a heptagonal…

Illustration of an elongated heptagonal/septagonal dipyramid that is formed by elongating a heptagonal bipyramid by inserting a heptagonal prism between the two congruent halves.

Elongated Heptagonal/Septagonal Dipyramid

Illustration of an elongated heptagonal/septagonal dipyramid that is formed by elongating a heptagonal…

Illustration of an elongated decagonal dipyramid that is formed by elongating a decagonal bipyramid by inserting a decagonal prism between the two congruent halves.

Elongated Decagonal Dipyramid

Illustration of an elongated decagonal dipyramid that is formed by elongating a decagonal bipyramid…

Illustration of an elongated decagonal dipyramid that is formed by elongating a decagonal bipyramid by inserting a decagonal prism between the two congruent halves.

Elongated Decagonal Dipyramid

Illustration of an elongated decagonal dipyramid that is formed by elongating a decagonal bipyramid…

Illustration of an elongated decagonal dipyramid that is formed by elongating a decagonal bipyramid by inserting a decagonal prism between the two congruent halves.

Elongated Decagonal Dipyramid

Illustration of an elongated decagonal dipyramid that is formed by elongating a decagonal bipyramid…

Leaves - simple; alternate (often alternate in pairs); edge unequally sharp-toothed, with the base entire. Outline - triangular. Apex - taper-pointed. Base - variable, more or less squared, sometimes slightly hollowed, rounded or pointed. Leaf/Stem - long and slender, about three quarters of an inch or more in length. Leaf - one and three quarters to three inches long. Smooth and shining on both sides. Bark - The outer bark of the mature trunk is chalky-white and thin, but not, like the bark of the Paper-birch, easily separable into layers. Usually it is marked with blackish dots and lines. Often the branchlets and twigs are blackish, and in very young trees the bark may be light reddish-brown, and marked with white dots. Found - on poor soil, from Delaware and Pennsylvania northward (mostly toward the coast), and in ornamental cultivation. It springs up abundantly over burned and abandoned lands. General Information - A slender, short-lived tree, twenty to thirty feet high, with white, soft wood, not durable; used largely in making spools, shoe pegs, etc., and for fuel. A still more graceful cultivated species is the European Weeping Birch (B. pendula). Its branches are very drooping, with more slender leaves, and a spray that is exceedingly light and delicate, especially in early spring.

Genus Betula, L. (Birch)

Leaves - simple; alternate (often alternate in pairs); edge unequally sharp-toothed, with the base entire.…

Leaves - simple; alternate; edge somewhat irregularly toothed. Outline - broad egg-shape (approaching triangular-shape). Apex - long, taper-pointed. Base - squared, slightly hollowed, or slightly pointed. Leaf/Stem - long and slender and much compressed sidewise. Leaf - two to three and a half inches long (much larger on young shoots); length and width nearly the same; smooth; ribs distinct and whitish on both sides, irregular, and branching. Bark - of trunk, light "granite-gray," smooth on young trunks, becoming somewhat rough with age, and with rounded up-and-down furrows. New and vigorous shoots are green, and marked with short white or brownish lines. Seeds - covered with a white, cotton-like fibre. Found - from Western New England southward to Western Florida, westward to the Rocky Mountains. The common "cottonwood" of the West, bordering all streams flowing east from the Rocky Mountains. General Information - A tree eighty to one hundred feet high. The very light and soft wood is largely used in making paper pulp, for light boxes, and for fuel. Experiments have been made in separating and weaving the cottony fibre of the poplar seeds. It can be manufactured into cloth, but not in paying quantity and quality.

Genus Populus, L. (Aspen, Poplar)

Leaves - simple; alternate; edge somewhat irregularly toothed. Outline - broad egg-shape (approaching…

Leaves - simple; alternate; edge deeply lobed (edges of lobes mostly entire, but notched and toothed towards the ends). Outline - broadly oval or broadly reverse egg-shape. Base - very short wedge-shape or squared. Ends of the lobes and of the teeth pointed and bristle-tipped. Leaf - four to eight inches long, bright green above, slightly lighter below; both surfaces smooth and shining. Lobes - five to nine, usually seven with the hollows rounded and very broad, and reaching about two thirds of the way to the middle rib. Most of the lobes widen and are deeply notched toward their end. Bark - of trunk, thick and rough, usually not quite as dark or as straight-furrowed as that of the Black Oak. The inner bark reddish. Acorns - variable. Cup - very thick, top-shaped, with large somewhat triangular egg-shaped, scales. Nut - one half to three fourths of an inch long; rounded or rounded egg-shape, about one third covered by the cup; kernel bitter and whitish. October. Found - from Southern Maine southward and westward; most common in the Middle and Southern States. General Information - A tree fifth to ninety feet high, with wood of less value than some of the other oaks. In the fall the leaves turn to a bright scarlet, or orange0scarlet, or crimson and red. They often cling throughout the winter. Quercus, possible from a Celtic word meaning to inquire, because it was among the oaks that the Druids oftenest practised their rites.

Genus Quercus, L. (Oak)

Leaves - simple; alternate; edge deeply lobed (edges of lobes mostly entire, but notched and toothed…

Leaves - compound (odd-feathered; leaflets, eleven to twenty-five); alternate; edge entire. Outline - oval or egg-shape. Apex, rounded. Base - rounded. Stem - of leaf, smooth, and covering the leaf-bud of the next year. Leaflets - very smooth, thin, often slightly tipped with the end of the mid-rib. Bark - of trunk, dark, rough, and very deeply ridged. The smaller branches and young trunks are armed with strong, triangular prickles, but these disappear when the parts are three to four inches thick. Flowers - showy and abundant; in long, loose clusters drooping from the sides of the branchlets; white; and very fragrant. May, June. Fruit - a smooth and rather blunt pod, two to three inches long, one and a half inches wide, four- to six-seeded. Seeds, dark brown. September. Found - Native in the Alleghany Mountains from Pennsylvania (Monroe County - Porter) to Georgia; but now very generally naturalized throughout the United States east of the Rocky Mountains. General Information - A tree usually forty to fifty feet high, sometimes ninety feet, and of rapid growth. Its wood is exceedingly hard and strong, and remarkable durable when in contact with the ground. It is used largely for posts, in ship-building, and in turnery, and it is preferred to all other native wood for tree nails. It is one of the most valuable trees of this or of any country. But is cultivation as a timber tree, which at one time was very general, has nearly ceased in the United State on account of the constant damage done by the grub of the Painted Clytus (Clytus pictus). This troublesome borer not only injures the new growth, but also pierces and detaches large branches, leaving the tree ragged and stunted.

Genus Robinia, L. (Locust)

Leaves - compound (odd-feathered; leaflets, eleven to twenty-five); alternate; edge entire. Outline…

A bow of prismatic colors formed from the reflection and refraction of the sun and water. In the diagram, S is the sun's rays, E is the eye. There are two bows: the primary is the inner brighter rainbow, and the secondary is dimmer and sometimes unseen.

Rainbow Diagram

A bow of prismatic colors formed from the reflection and refraction of the sun and water. In the diagram,…

Obock Camel Post Stamp (5 p) from 1893

Obock 5 P Camel Post Stamp, 1893

Obock Camel Post Stamp (5 p) from 1893

Colombian Republic Stamp (2-1/2 centavos) from 1865

Colombian Republic 2-1/2 Centavos Stamp, 1865

Colombian Republic Stamp (2-1/2 centavos) from 1865

The figure shows a 30 degree triangle made from a square depicting the harmony and syzygy of tides in four different places (the four corners of the square).

Tide Theory, Triangle

The figure shows a 30 degree triangle made from a square depicting the harmony and syzygy of tides in…

The figure shows a 30 degree triangle made from a square depicting the harmony and syzygy of tides in four different places (the four corners of the square).

Tide Theory, Triangle

The figure shows a 30 degree triangle made from a square depicting the harmony and syzygy of tides in…

Illustration of pattern showing steps to make a box.

Pattern To Make A Box

Illustration of pattern showing steps to make a box.

Illustration of pattern showing steps to make a house. The house is a composite figure made up of a triangular prism and a rectangular solid.

Pattern To Make A House

Illustration of pattern showing steps to make a house. The house is a composite figure made up of a…

Illustration of pattern showing steps to make a barn. The barn is a composite figure made up of a triangular prism and a rectangular solid.

Pattern To Make A Barn

Illustration of pattern showing steps to make a barn. The barn is a composite figure made up of a triangular…

An illustration of a rectangular prism with dimensions of 4 ft. by 1 ft. by 1 ft..

4 By 1 By 1 Rectangular Prism

An illustration of a rectangular prism with dimensions of 4 ft. by 1 ft. by 1 ft..

An illustration of a rectangular prism with dimensions of 4 ft. by 2 ft. by 1 ft..

4 By 2 By 1 Rectangular Prism

An illustration of a rectangular prism with dimensions of 4 ft. by 2 ft. by 1 ft..

An illustration of a rectangular prism with dimensions of 4 ft. by 2 ft. by 2 ft..

4 By 2 By 2 Rectangular Prism

An illustration of a rectangular prism with dimensions of 4 ft. by 2 ft. by 2 ft..

A triangular stem.

Triangular Stem

A triangular stem.

A triangular leaf.

Triangular Leaf

A triangular leaf.

A trowel-shaped leaf.

Trowel-Shaped Leaf

A trowel-shaped leaf.

"Hastate.--Formed like the head of an ancient halbert." -Newman, 1850

Hastate

"Hastate.--Formed like the head of an ancient halbert." -Newman, 1850

A hastate leaf that is triangular in shape with basal lobes.

Hastate Leaf

A hastate leaf that is triangular in shape with basal lobes.

Isometric of a prism with a semicircular top.

Prism With Semicircular Top

Isometric of a prism with a semicircular top.

Illustration of a plan and elevation of an oblique pentagonal pyramid.

Oblique Pentagonal Pyramid

Illustration of a plan and elevation of an oblique pentagonal pyramid.

Illustration of the isometric of an oblique pentagonal pyramid.

Isometric of Oblique Pentagonal Pyramid

Illustration of the isometric of an oblique pentagonal pyramid.

Illustration of the isometric of a skeleton of a box.

Isometric Of A Box

Illustration of the isometric of a skeleton of a box.

Illustration of the isometric of a carpenter's bench.

Isometric Of A Carpenter's Bench

Illustration of the isometric of a carpenter's bench.

Illustration of stairs; 3-dimensional view of 4 steps. The staircase can be created by combining/stacking various sizes of rectangular solids.

Isometric of Stairs

Illustration of stairs; 3-dimensional view of 4 steps. The staircase can be created by combining/stacking…

Illustration of the isometric of a hollow cylinder.

Hollow Cylinder

Illustration of the isometric of a hollow cylinder.

Illustration of model created by combining non regular geometric solids.

Combination of Geometric Solids

Illustration of model created by combining non regular geometric solids.

Illustration of an oblique view of a rectangular solid/prism at 30°.

Oblique View Of Rectangular Solid

Illustration of an oblique view of a rectangular solid/prism at 30°.

Illustration of an oblique view of a rectangular solid/prism at 45°.

Oblique View Of Rectangular Solid

Illustration of an oblique view of a rectangular solid/prism at 45°.

Illustration of an oblique view of a rectangular solid/prism at 60°.

Oblique View Of Rectangular Solid

Illustration of an oblique view of a rectangular solid/prism at 60°.

Illustration of an oblique view of a hollow cylinder.

Oblique View Of Hollow Cylinder

Illustration of an oblique view of a hollow cylinder.

Illustration of an oblique view of a hollow cylinder. The portion removed from the center of the cylinder is in the shape of a rectangular prism.

Oblique View Of Hollow Cylinder

Illustration of an oblique view of a hollow cylinder. The portion removed from the center of the cylinder…

Illustration of a shaded section of a hollow cylinder viewed from the side.

Hollow Cylinder

Illustration of a shaded section of a hollow cylinder viewed from the side.

A detached triangular work in fortification, with two embankments which form a projecting angle. In the figure B B is the ravelin with A its redout, and CC its ditch, DD being the main ditch of the fortress,and E the passage giving access from the fortress to the ravelin.

Ravelin

A detached triangular work in fortification, with two embankments which form a projecting angle. In…

An illustration of an elliptical prism.

Elliptical Prism

An illustration of an elliptical prism.

A bony structure located at the bottom of the spine. The human sacrum forms the back part of the pelvis, is roughly triangular in shape, consists of five united vertebrae, and from its solidity it is well adapted to serve as the keystone of the pelvic arch.

Pelvic Bone, Male

A bony structure located at the bottom of the spine. The human sacrum forms the back part of the pelvis,…

Showing different types of parallel prisms: rectangular, right triangular, acute triangular, and obtuse triangular.

Parallel Prisms

Showing different types of parallel prisms: rectangular, right triangular, acute triangular, and obtuse…

Showing different types of oblique prisms: rectangular, right triangular, acute triangular, and obtuse triangular.

Oblique Prisms

Showing different types of oblique prisms: rectangular, right triangular, acute triangular, and obtuse…

A rectangular prism with labeled sides: AAAA are the four vertical parallel corners. BBBB and CCCC are the horizontal parallel edges.

Rectangular Prism

A rectangular prism with labeled sides: AAAA are the four vertical parallel corners. BBBB and CCCC are…

Types of parallel prisms: right triangular prism, isosceles triangular prism, rectangular prism, cylinder.

Parallel Prisms

Types of parallel prisms: right triangular prism, isosceles triangular prism, rectangular prism, cylinder.

Types of oblique prisms: right triangular prism, isosceles triangular prism, rectangular prism, cylinder.

Oblique Prisms

Types of oblique prisms: right triangular prism, isosceles triangular prism, rectangular prism, cylinder.

A, B, and C show three types of triangular prisms: right, isosceles, and equilateral. When put together with rectangular prisms, they create the three basic house forms. D is a shed roof and E and F are gable roofs.

Drawing House Forms

A, B, and C show three types of triangular prisms: right, isosceles, and equilateral. When put together…

Illustration of a 5 in. by 3 in. by 4 in. rectangular solid with each cube in the solid representing one cubic inch. This can be used when explaining volume.

Volume Of A Rectangular Solid

Illustration of a 5 in. by 3 in. by 4 in. rectangular solid with each cube in the solid representing…

Illustration of a triangular prism; a prism whose bases are triangles.

Triangular Prism

Illustration of a triangular prism; a prism whose bases are triangles.

Illustration of a square prism; a prism whose bases are squares.

Square Prism

Illustration of a square prism; a prism whose bases are squares.

Illustration of a pentagonal prism showing, "If a piece of paper is fitted to cover the convex surface of a prism or a cylinder, and then unrolled, its form will be that of a rectangle, as ABCD."

Surfaces Of A Prism

Illustration of a pentagonal prism showing, "If a piece of paper is fitted to cover the convex surface…

Illustration of a cylinder showing, "If a piece of paper is fitted to cover the convex surface of a prism or a cylinder, and then unrolled, its form will be that of a rectangle, as ABCD."

Surfaces Of A Cylinder

Illustration of a cylinder showing, "If a piece of paper is fitted to cover the convex surface of a…