"In <em>optics</em>, a deviation in the rays of light when unequally refracted by a lens or reflected by a mirror, so that they do not converge and meet in a point or focus, but separate, forming an indistinct image of the object, or an indistinct image with prismatically colored edges."-Wright, 1902

Aberration

"In optics, a deviation in the rays of light when unequally refracted by a lens or reflected…

"Monoclinic. Crystals prismatic in habit; the prism faces make angles of 55 and 125 degrees with each other." &mdash; Ford, 1912

Amphibole

"Monoclinic. Crystals prismatic in habit; the prism faces make angles of 55 and 125 degrees with each…

"Hexagonal; tri-pyramidal. Crystals usually long prismatic in habit; sometimes short prismatic or tabular. Usually terminated by prominent pyramid of first order and frequently a basal plane." &mdash; Ford, 1912

Apatite

"Hexagonal; tri-pyramidal. Crystals usually long prismatic in habit; sometimes short prismatic or tabular.…

"Hexagonal; tri-pyramidal. Crystals usually long prismatic in habit; sometimes short prismatic or tabular. Usually terminated by prominent pyramid of first order and frequently a basal plane." &mdash; Ford, 1912

Apatite

"Hexagonal; tri-pyramidal. Crystals usually long prismatic in habit; sometimes short prismatic or tabular.…

"Orthorhombic. Acicular pyramidal; consisting of a prism terminated by a combination of a very steep pyramid and brachydome." &mdash; Ford, 1912

Aragonite

"Orthorhombic. Acicular pyramidal; consisting of a prism terminated by a combination of a very steep…

"Orthorhombic. Tabular; consisting of prominent brachypinacoid faces modified by a prism and a low brachydome." &mdash; Ford, 1912

Aragonite

"Orthorhombic. Tabular; consisting of prominent brachypinacoid faces modified by a prism and a low brachydome."…

"Orthohombic. Crystals usually tabular parallel to base; often diamond shaped because of the presence of a short prism. Both macro- and brachydomes usually present, either beveling the corners of the diamond-shaped crystals, or if the prism faces are wanting, beveling the edges of the tavles and forming rectangular prismatic-shaped crystals elongated parallel to either the brachy- or macro-axis." &mdash; Ford, 1912

Barite

"Orthohombic. Crystals usually tabular parallel to base; often diamond shaped because of the presence…

"Orthohombic. Crystals usually tabular parallel to base; often diamond shaped because of the presence of a short prism. Both macro- and brachydomes usually present, either beveling the corners of the diamond-shaped crystals, or if the prism faces are wanting, beveling the edges of the tavles and forming rectangular prismatic-shaped crystals elongated parallel to either the brachy- or macro-axis." &mdash; Ford, 1912

Barite

"Orthohombic. Crystals usually tabular parallel to base; often diamond shaped because of the presence…

Isometric of a box with a cover.

Isometric of a Box With a Cover

Isometric of a box with a cover.

Isometric of a box with a cover - end view.

Isometric of a Box With a Cover

Isometric of a box with a cover - end view.

Illustration of the isometric of a skeleton of a box.

Isometric Of A Box

Illustration of the isometric of a skeleton of a box.

"This consists of four faces perpendicular to the vertical axis." -The Encyclopedia Britannica 1910

Brachy-prism and Macro-pinacoid

"This consists of four faces perpendicular to the vertical axis." -The Encyclopedia Britannica 1910

Illustration of the isometric of a carpenter's bench.

Isometric Of A Carpenter's Bench

Illustration of the isometric of a carpenter's bench.

"Catadioptric Holophote.&mdash;Part of the anterior hemisphere of rays is intercepted and at once parallelized by the lens L, whose principal focus (i.e., for parallel rays) is in the center of the flame, while the remainder is intercepted and made parallel by the paraboloid a, and thus the double agents in Fresnel's design are dispensed with. The rays of the posterior hemisphere are reflected by the spherical mirror b back again through the foxus, whence passing onwards one portion of them falls on the lens and the rest on the paraboloid, so as finally to emerge in union with and parallel to the front rays." &mdash;The Encyclopedia Britannica, 1910

Catadioptric Holophote

"Catadioptric Holophote.—Part of the anterior hemisphere of rays is intercepted and at once parallelized…

"Catadioptric Holophote.&mdash;Part of the anterior hemisphere of rays is intercepted and at once parallelized by the lens L, whose principal focus (i.e., for parallel rays) is in the center of the flame, while the remainder is intercepted and made parallel by the paraboloid a, and thus the double agents in Fresnel's design are dispensed with. The rays of the posterior hemisphere are reflected by the spherical mirror b back again through the foxus, whence passing onwards one portion of them falls on the lens and the rest on the paraboloid, so as finally to emerge in union with and parallel to the front rays." &mdash;The Encyclopedia Britannica, 1910

Catadioptric Holophote

"Catadioptric Holophote.—Part of the anterior hemisphere of rays is intercepted and at once parallelized…

"...a combination of a bipyramid of the first order with a ditetragonal bipyramid and the prism of the second order." -The Encyclopedia Britannica 1910

Combination of a bipyramid and prism

"...a combination of a bipyramid of the first order with a ditetragonal bipyramid and the prism of the…

Combination of holohedral tetragonal forms.

Combination of Tetragonal Prism and Basal Pinacoid

Combination of holohedral tetragonal forms.

"Fixed Conensing Light for a Single Sector, 1850.&mdash;The holophote Light pLp throws its whole light on straight condensing prisms c, each of which distributes the rays over the required sector." &mdash;The Encyclopedia Britannica, 1910

Condensing Light

"Fixed Conensing Light for a Single Sector, 1850.—The holophote Light pLp throws its whole light…

"Condensing Octant.&mdash;The central fixed apparatus bb with spherical mirror dd throws its rays directly over the angle of 45 degrees pgp, while the supplemental rays fall upon the straight condensing prisms p, each of which spreads the incident rays parallel to the corresponding rays in the central angle pgp. In this way the whole of the front hemisphere of rays is parallelized in the vertical plane and spread equally over the 45 degree in azimuth." &mdash;The Encyclopedia Britannica, 1910

Condensing Octant

"Condensing Octant.—The central fixed apparatus bb with spherical mirror dd throws its rays directly…

"Condensing Octant.&mdash;The central fixed apparatus bb with spherical mirror dd throws its rays directly over the angle of 45 degrees pgp, while the supplemental rays fall upon the straight condensing prisms p, each of which spreads the incident rays parallel to the corresponding rays in the central angle pgp. In this way the whole of the front hemisphere of rays is parallelized in the vertical plane and spread equally over the 45 degree in azimuth." &mdash;The Encyclopedia Britannica, 1910

Condensing Octant

"Condensing Octant.—The central fixed apparatus bb with spherical mirror dd throws its rays directly…

"Condensing Quadrant.&mdash;The fixed apparatus bbb, with spherical mirror behind, throws its rays directly through the angle of 90 degrees afa', while the supplementary rays falling on the straight condensing prisms p, p, p', p' are sent out parallel to the corresponding rays in the unobstructed central quadrant of the main apparatus. The whole light will therefore be condensed equally over 90 degrees." &mdash;The Encyclopedia Britannica, 1910

Condensing Quadrant

"Condensing Quadrant.—The fixed apparatus bbb, with spherical mirror behind, throws its rays directly…

Development and top completion exercise problem of the cone by dividing the base into equal parts and creating an arc to revolve the sides of the plane.

Development Exercise of Cone

Development and top completion exercise problem of the cone by dividing the base into equal parts and…

An exercise problem to complete the top and develop, stretched out, image of the flange and hood cones by using series of cone development.

Development Exercise of Flange and Hood Cones

An exercise problem to complete the top and develop, stretched out, image of the flange and hood cones…

"Hexagonal-rhombohedral. Crystals usually prismatic in habit or tapering hexagonal pyramids." &mdash; Ford, 1912

Corundum

"Hexagonal-rhombohedral. Crystals usually prismatic in habit or tapering hexagonal pyramids." —…

"Hexagonal-rhombohedral. Crystals usually prismatic in habit or tapering hexagonal pyramids." &mdash; Ford, 1912

Corundum

"Hexagonal-rhombohedral. Crystals usually prismatic in habit or tapering hexagonal pyramids." —…

"...represents a crystal of dioptase with the fundamental rhombohedron (r) and the hexagonal prism of the second order (m) combined with the rhombohedron (s)." -The Encyclopedia Britannica 1910

Crystal of Dioptase

"...represents a crystal of dioptase with the fundamental rhombohedron (r) and the hexagonal prism of…

"A cube is a prism whose faces are ends are squares. All the faces of a cube are equal." &mdash;Hallock 1905

Cube

"A cube is a prism whose faces are ends are squares. All the faces of a cube are equal." —Hallock…

Illustration of 3-dimensional cube with hidden edges shown.

Cube

Illustration of 3-dimensional cube with hidden edges shown.

Illustration of 128 congruent cubes stacked so they form a rectangular solid that measures 4 by 4 by 8. A 3-dimensional representation on a 2-dimensional surface that can be used for testing depth perception and identifying and counting cubes, edges, and faces.

128 Stacked Congruent Cubes

Illustration of 128 congruent cubes stacked so they form a rectangular solid that measures 4 by 4 by…

An exercise problem in creating a development or rolled out surface of a cylinder in a 4" by 5" drawing area.

Development Exercise of Cylinder

An exercise problem in creating a development or rolled out surface of a cylinder in a 4" by 5" drawing…

Illustration of the isometric of a hollow cylinder.

Hollow Cylinder

Illustration of the isometric of a hollow 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.

Right circular cylinder inscribed in a pentagonal prism. Or, Pentagonal prism circumscribed about a cylinder.

Cylinder Inscribed in Pentagonal Prism

Right circular cylinder inscribed in a pentagonal prism. Or, Pentagonal prism circumscribed about a…

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 used to show finding the volume of a pentagonal prism.

Volume Of Cylinder

Illustration used to show finding the volume of a pentagonal prism.

"Perfect Form of Dioptric Holophote for an Oil Flame.&mdash;By combining the back prisms ga, hc just described with a semi-holophote abc subtending 180 degrees and a portion of the dioptric spherical mirror ijk, no light is lost on the burner, and all the rays are parallelized, so that this apparatus, being all of glass, is both geometrically and physically perfect." &mdash;The Encyclopedia Britannica, 1910

Dioptric Holophote

"Perfect Form of Dioptric Holophote for an Oil Flame.—By combining the back prisms ga, hc just…

"First Application of Total Reflexion to Fixed Lights. In this apparatus Fresnel substituted his totally reflecting prism p and lens R for Marcet's reflector, and thus distributed the whole light equally over the horizon by means of dioptric agents alone. This was the first application of total reflexion to lighthouse apparatus, and this beautiful instrument continues till now in universal use." &mdash;The Encyclopedia Britannica, 1910

Dioptric Light

"First Application of Total Reflexion to Fixed Lights. In this apparatus Fresnel substituted his totally…

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…

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 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 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 square dipyramid that is formed by elongating a square bipyramid by inserting a square prism between the two congruent halves.

Elongated Square Dipyramid

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

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&deg;.

Elongated Square Dipyramid

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

A development or rolled out image exercise problem of the dome and finding the true shape of the hip, or edge, of the dome by using projections or with dividers.

Development Exercise of Dome and True Shape of Hip

A development or rolled out image exercise problem of the dome and finding the true shape of the hip,…

"This is a form consisting of six rectangular vertical faces each of which intersects two of the horizontal axes equally and the intermediate horizontal axis at one-half this distance." &mdash; Ford, 1912

Prism of the first order

"This is a form consisting of six rectangular vertical faces each of which intersects two of the horizontal…

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which belongs a number of forms having some property in common. In order to classify these different crystals, the existence of certain lines within the crystal, called axes, is assumed, around which the form can be symmetrically build up. These axes are assumed to intersect in the center of the crystal, and to pass through from one side to the other." &mdash; Hallock, 1905

First Right Square Prism

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which…

"Fresnel's Revolving Light. &mdash;In this form of revolving light the central burner is surrounded by annular lenses L, and a compound arrangement of inclined trapezoidal lenses L' and plane silvered mirrors M. The inclined lenses fit closely to each other and form a pyramidal dome, and the light, intercepted by them, is sent upwards in inclined beams until, falling upon the plane mirrors M, it is sent outwards in horizontal parallelized beams. All these optical agents are made to revolve round the central lamp, and the sailor receives a full flash when the axis of one of the emerging beams passes his eye, and as soon as it passes him he is in darkness until the next beam comes round." &mdash;The Encyclopedia Britannica, 1910

Fresnels Revolving Light

"Fresnel's Revolving Light. —In this form of revolving light the central burner is surrounded…

"Fresnel's Revolving Light. &mdash;In this form of revolving light the central burner is surrounded by annular lenses L, and a compound arrangement of inclined trapezoidal lenses L' and plane silvered mirrors M. The inclined lenses fit closely to each other and form a pyramidal dome, and the light, intercepted by them, is sent upwards in inclined beams until, falling upon the plane mirrors M, it is sent outwards in horizontal parallelized beams. All these optical agents are made to revolve round the central lamp, and the sailor receives a full flash when the axis of one of the emerging beams passes his eye, and as soon as it passes him he is in darkness until the next beam comes round." &mdash;The Encyclopedia Britannica, 1910

Fresnels Revolving Light

"Fresnel's Revolving Light. —In this form of revolving light the central burner is surrounded…

"Fresnel's Revolving Light. &mdash;In this form of revolving light the central burner is surrounded by annular lenses L, and a compound arrangement of inclined trapezoidal lenses L' and plane silvered mirrors M. The inclined lenses fit closely to each other and form a pyramidal dome, and the light, intercepted by them, is sent upwards in inclined beams until, falling upon the plane mirrors M, it is sent outwards in horizontal parallelized beams. All these optical agents are made to revolve round the central lamp, and the sailor receives a full flash when the axis of one of the emerging beams passes his eye, and as soon as it passes him he is in darkness until the next beam comes round." &mdash;The Encyclopedia Britannica, 1910

Fresnels Revolving Light

"Fresnel's Revolving Light. —In this form of revolving light the central burner is surrounded…

"Fresnel's Revolving Light. &mdash;In this form of revolving light the central burner is surrounded by annular lenses L, and a compound arrangement of inclined trapezoidal lenses L' and plane silvered mirrors M. The inclined lenses fit closely to each other and form a pyramidal dome, and the light, intercepted by them, is sent upwards in inclined beams until, falling upon the plane mirrors M, it is sent outwards in horizontal parallelized beams. All these optical agents are made to revolve round the central lamp, and the sailor receives a full flash when the axis of one of the emerging beams passes his eye, and as soon as it passes him he is in darkness until the next beam comes round." &mdash;The Encyclopedia Britannica, 1910

Fresnels Revolving Light

"Fresnel's Revolving Light. —In this form of revolving light the central burner is surrounded…

A hand holding a square pyramid, suspended by a string.

Hand and pyramid

A hand holding a square pyramid, suspended by a string.

Projection of a hexagonal bar.

Projection of Hexagonal Bar

Projection of a hexagonal bar.