 ### Froebel's Divided Cube (Complex)

This image shows one of Friedrich Froebel's divided cube (this one divided into many smaller cubes and… ### Hand and pyramid

A hand holding a square pyramid, suspended by a string. ### Projection of Hexagonal Bar

Projection of a hexagonal bar. ### Projection of Hexagonal Nut

Projection of a hexagonal nut. ### Hexagonal Prism

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which… ### Hexagonal Prism and Basal Pinacoid

"...shows a combination of a hexagonal prism (m) with the basal pinacoid (c)." -The Encyclopedia Britannica… ### Hexagonal Prism of the First Order

"Hexagonal prism of the first order, consisting of six faces also parallel to the hexad axis, but perpendicular… ### Development of Hexagonal Prism

An illustration of a hexagonal prism rolled out, or "stretched out" in the straight line AB. "Holophotal Catadioptric Apparatus Revolving round a Central Flame." —The Encyclopedia Britannica,… ### Hydrous Nickel Sulphate

This form shows the planes given on a crystal of hydrous nickel sulphate: the basal pinacoid, (c); three… Also known as Stolzite, this crystal is bounded by the unit pyramid of the first order, P, {111} (o),… ### Lenses of Various Forms

"a, prism; b, plane glass; c, spherical lens; d, double-convex; e, plano-convex, f, double-concave;… ### Macro-prism and Brachy-pinacoid

"This consists of four faces parallel to the brachy axis." -The Encyclopedia Britannica 1910 ### Marcasite

"Orthorhombic. Crystals commonly tabular parallel to basal plane, showing also short prisms and low… ### Development Exercise of Octagonal Light Shade

A problem exercise creating a stretched out or developed image of the octagonal light shade by using… ### Development Exercise of Octagonal Roof and True Shape of Rafter

Problem exercise in drawing a development or a stretchout image of the octagonal roof and finding the… ### Orthoclase

"Monoclinic. Crystals are usually prismatic in habit and have as prominent forms, clinopinacoid, base,… ### Orthorhombic Crystal of Olivine

This is an orthorhombic crystal of olivine. It is formed by the orthorhombic prism in combination with… ### Orthorhombic Crystal of Topaz

This form shows the fundamental prism (p) on a crystal of topaz, in combination with another prism,… ### Parallelopiped

Illustration of a parallelopiped - a prism with a parallelogram as its base ### Parallelopiped

Illustration of a parallelopiped - a prism with a parallelogram as its base ### Equal and Parallel Opposite Faces of a Parallelopiped

Diagram used to prove the theorem: "The opposite faces of a parallelopiped are equal and parallel." ### Parallelopiped with Plane Passing Through

Illustration of a parallelopiped with a plane passing through two diagonally opposite edges. The plane… ### Parallelopiped with Plane Passing Through

Illustration of a parallelopiped with a plane passing through two diagonally opposite edges. The plane… ### Parallelopiped Showing Volume

Illustration of a parallelopiped (a prism with a parallelogram as its base) used to demonstrate that… ### Parallelopipedon

"A parallelopipedon is a prism whose bases (ends) are parallelograms." —Hallock 1905 ### Relationship Between 2 Parallelopipeds With Equal Altitudes

Diagram used to prove the theorem: "The rectangular parallelopipeds which have two dimensions in common… ### Relationship Between Dimensions of Parallelopipeds

Diagram used to prove the theorem: "The rectangular parallelopipeds are to each other as the product… ### Volume of Parallelopiped

Diagram used to prove the theorem: "The volume of a any parallelopiped is equal to the product of its… ### Volume of Rectangular Parallelopiped

Diagram used to prove the theorem: "The volume of a rectangular parallelopiped is equal to the product… ### Phenacite

This crystal is mainly terminated by a rhombohedron of the third order, (x). With this form are associated… ### Primitive Crystal

"If the base is a square and the prism stands erect—that is, if its sides or lateral planes, as… ### Primitive Crystal

"When the base is a rectangle instead of a square, the form is a right rectangular prism." —The… ### Primitive Crystal

"When the base is a rhombus, and the prism stands erect, the form is a right rhombic prism." —The… ### Primitive Crystal

"When the base is a rhomboid, and the prism stands erect, it is only the opposite laeral faces that… ### Prism

A transparent body, with usually three sides and two equal and parallel triangular ends or bases. ### Prism

"Right rhombic prism." — Hallock, 1905 ### Prism

"Doubly oblique prism." — Hallock, 1905 ### Prism

"A prism is a transparent body with two refraction surfaces that lie in intersecting planes. The angle… ### Prism

"A prism is a piece of glass, having for its sides three plane surfaces and for its ends two equal and… ### Prism

Illustration of a prism - a polyhedron of which two faces are equal polygons in parallel planes, and… ### Prism and Basal Pinacoid

Holohedral orthorhombic combination ### Pentagon Development Prism Exercise

An exercise developed to draw a rolled out or development of the pentagon prism in a 4" by 5" surface. ### Pentagonal Prism Development Exercise

An exercise in drawing a pentagonal prism development or rolled out image in a 4" by 5" area. ### Triangular Prism Development Exercise

An illustration to exercise a stretched out, or development, image of the triangular prism using 4"… ### Triangle Prism Exercise

An illustration to draw triangle prism's development, or stretched out surfaces, in a 4" by 5" surface. ### Prism Spectroscope from the Late 19th Century

"...a tube with a slit at the further end through which the light enters, and at the other end a collimating… ### Cathetal Prism

"Cathetal prisms readily yield the phenomena of total reflection as shown, and are often used when light… ### Combination of Prisms

An illustration of a combination formed by different prisms ### Ditetragonal prism

"The dietetragonal prism is a form consisting of eight rectangular vertical faces, each of which intersects… ### Dihexagonal prism

"The dihexagonal prism has twelve rectangular vertical faces, each of which intersects all three of… ### First order prism

"The prism of the first order consists of four rectangular vertical faces, each of which intersects… ### Hexagonal Prism

Prism with hexagonal bases and dimensions 8 and 12 given. ### Lateral Area of A Prism

Diagram used to prove the theorem: "The lateral area of a prism is equal to the product of a lateral… ### Orthohombie prism

"Crystal faces are described according to their relations to the crystallographic axes. A series of… ### Intersection of a Prism and a Plane

Illustration of the intersection of a prism and a plane. ### Rectangular Prism

Prism with rectangular bases and cubes drawn in. ### Right Triangular Prism

Prism with triangular bases. ### Second order prism

"The prism of the second order consists of four rectangular vertical faces, each of which intersects…