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A cylinder is a body of uniform diameter throughout its entire length, whose ends are equal parallel circles.

Cylinder

A cylinder is a body of uniform diameter throughout its entire length, whose ends are equal parallel…

A sphere is a solid bounded by a uniformly curved surface, every point of which is equally distant from a point within, called the center.

Sphere

A sphere is a solid bounded by a uniformly curved surface, every point of which is equally distant from…

Conic sections, cones divided by a plane.

Conic Sections

Conic sections, cones divided by a plane.

Forms of crystals.

Crystals, Forms of

Forms of crystals.

"That point in which a right line drawn from the eye parallel to another given right line cuts the picture of plane."-Whitney, 1902

Accidental Point

"That point in which a right line drawn from the eye parallel to another given right line cuts the picture…

"The Metacenter is the point of intersection of the vertical line passing through the center of gravity of a floating body in equilibrio, and a vertical line through the center of gravity of the fluid displaced, if the body be turned through a small angle, so that the axis takes a position inclined to the vertical. If the metacenter is above the center of gravity, the position of the body is stable; if below it, it is unstable."—(Charles Leonard-Stuart, 1911)

Metacenter

"The Metacenter is the point of intersection of the vertical line passing through the center of gravity…

The contours of a cone are circles of different sizes, one within another, and the same distance apart, because the slope is at all points the same." — Moss, 1914

Contours of a cone

The contours of a cone are circles of different sizes, one within another, and the same distance apart,…

"The contours of a half sphere are a series of circles, far apart near the center (top) and near together at the outside (bottom), showing that the slope of a hemisphere varies at all points, being nearly flat on top and increasing in steepness near bottom." — Moss, 1914

Contours of a half sphere

"The contours of a half sphere are a series of circles, far apart near the center (top) and near together…

"The contours of a concave (hollowed out) cone are close together at the center (top), and far apart at the outside (bottom)." — Moss, 1914

Contours of a concave cone

"The contours of a concave (hollowed out) cone are close together at the center (top), and far apart…

A regular solid body, with six equal square sides.

Cube

A regular solid body, with six equal square sides.

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

Prism

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

A body of roller-like form, of which the longitudinal section is oblong, and the cross-section is circular.

Cylinder

A body of roller-like form, of which the longitudinal section is oblong, and the cross-section is circular.

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

Hand and pyramid

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

"In the diagram, let AB and AC represent two forces acting upon the point, A. Draw the two dotted lines to complete the parallelogram." — Avery, 1895

Parallelogram

"In the diagram, let AB and AC represent two forces acting upon the point, A. Draw the two dotted lines…

A line of interlocking circles.

Circles

A line of interlocking circles.

"A crystal has a center of symmetry if an imaginary line is passed from some point on its surface through its center, and a similar point is found on the line at an equal distance beyond the center." — Ford, 1912

Symmetry plane

"A crystal has a center of symmetry if an imaginary line is passed from some point on its surface through…

"A crystal has a center of symmetry if an imaginary line is passed from some point on its surface through its center, and a similar point is found on the line at an equal distance beyond the center." — Ford, 1912

Symmetry axis

"A crystal has a center of symmetry if an imaginary line is passed from some point on its surface through…

"A crystal has a center of symmetry if an imaginary line is passed from some point on its surface through its center, and a similar point is found on the line at an equal distance beyond the center." — Ford, 1912

Symmetry center

"A crystal has a center of symmetry if an imaginary line is passed from some point on its surface through…

"Crystal faces are described according to their relations to the crystallographic axes. A series of numbers which indicate the relative distances by which a face intersects the different axes are called its parameters. " — Ford, 1912

Orthorhombie pyramid

"Crystal faces are described according to their relations to the crystallographic axes. A series of…

"Crystal faces are described according to their relations to the crystallographic axes. A series of numbers which indicate the relative distances by which a face intersects the different axes are called its parameters. " — Ford, 1912

Orthohombie prism

"Crystal faces are described according to their relations to the crystallographic axes. A series of…

"The forms present upon it are two pyramids of different slope but each intersecting all three of the crystal axes when properly extended. The lower pyramid intersects the two horizontal axes at distances which are proportional to their unit lengths and if it was extended as shown by the dotted lines would also cut the vertical axis at a distance proportional to its unit length." — Ford, 1912

Sulphur crystal

"The forms present upon it are two pyramids of different slope but each intersecting all three of the…

"A crystal form does not necessarily make a solid figure. One such an example is this, of the Monoclinic System.

Crystal of the monoclinic system

"A crystal form does not necessarily make a solid figure. One such an example is this, of the Monoclinic…

A cube.

Cube

A cube.

An octohedron.

Octahedron

An octohedron.

"When a corner or an edge of one form is replaced by a face of another form, the first is said to be trunctuated by the second." — Ford, 1912

Cube trunctuated by octahedron

"When a corner or an edge of one form is replaced by a face of another form, the first is said to be…

"When a corner or an edge of one form is replaced by a face of another form, the first is said to be trunctuated by the second." — Ford, 1912

Octahedron trunctuated by cube

"When a corner or an edge of one form is replaced by a face of another form, the first is said to be…

A distorted octahedron.

Distorted octahedron

A distorted octahedron.

Dodecahedron.

Dodecahedron

Dodecahedron.

A distorted dodecahedron

Distorted dodecahedron

A distorted dodecahedron

"A penetration twin, since the two individuals interpenetrate each other." — Ford, 1912

Twinned cubes

"A penetration twin, since the two individuals interpenetrate each other." — Ford, 1912

"A contact twin, since the two individuals lie simply in contact with each other upon a certain plane." — Ford, 1912

Twinned octahedron

"A contact twin, since the two individuals lie simply in contact with each other upon a certain plane."…

"A combination of dodecahedron and cube." — Ford, 1912

Cube and dodecahedron

"A combination of dodecahedron and cube." — Ford, 1912

A combination of octahedron and dodecahedron.

Octahedron and dodecahedron

A combination of octahedron and dodecahedron.

A dodecahedron and octahedron

Dodecahedron and octahedron

A dodecahedron and octahedron

A cube, octahedron, and dodecahedron.

Cube, octahedron and dodecahedron

A cube, octahedron, and dodecahedron.

"The tetrahexahedron is a form composed of twenty-four isoceles triangular faces, each of which intersects one axis at unity, the second at some multiple, and is parallel to the third." — Ford, 1912

Tetrahexahedron

"The tetrahexahedron is a form composed of twenty-four isoceles triangular faces, each of which intersects…

"A cube with its edges beveled by the faces of a tetrahexahedron." — Ford, 1912

Cube and tetrahexahedron

"A cube with its edges beveled by the faces of a tetrahexahedron." — Ford, 1912

"The trapezohedron is a form composed of twenty-four trapezium-shaped faces, each of which intersects one of the crystallographic axes at unity and the other two at equal multiples." — Ford, 1912

Trapezohedron

"The trapezohedron is a form composed of twenty-four trapezium-shaped faces, each of which intersects…

A dodecahedron and trapezohedron.

Dodecahedron and trapezohedron

A dodecahedron and trapezohedron.

A dodecahedron and trapezohedron

Dodecahedron and trapezohedron

A dodecahedron and trapezohedron

"A combination of cube and trapezohedron." — Ford, 1912

Cube and trapezohedron

"A combination of cube and trapezohedron." — Ford, 1912

"The trisoctahedron is a form composed of twenty-four isosceles triangular faces, each of which intersects two of the crystallographic axes at unity and the third axis at some multiple. There are various trisoctahedrons the faces of which have different inclinations." — Ford, 1912

Trisoctahedron

"The trisoctahedron is a form composed of twenty-four isosceles triangular faces, each of which intersects…

"A combination of a trisoctahedron and an octahedron. It will be noted that the faces of the trisoctahedron bevel the edges of the ocrahedron." — Ford, 1912

Octahedron and trisoctahedron

"A combination of a trisoctahedron and an octahedron. It will be noted that the faces of the trisoctahedron…

"The hexoctahedron is a form composed of forty-eight triangular faces, each of which cuts differently on all three crystallographic axes. There are several hexoctahedrons, which have varying ratios of intersection with the axes." — Ford, 1912

Hexoctahedron

"The hexoctahedron is a form composed of forty-eight triangular faces, each of which cuts differently…

"A combination of cube and hexoctahedron." — Ford, 1912

Cube and hexoctahedron

"A combination of cube and hexoctahedron." — Ford, 1912

"A combination of dodecahedron and hexoctahedron." — Ford, 1912

Dodecahedron and hexoctahedron

"A combination of dodecahedron and hexoctahedron." — Ford, 1912

"A combination of of dodecahedron, trapezohedron, and hexoctahedron." — Ford, 1912

Dodecahedron, trapezohedron and hexoctahedron

"A combination of of dodecahedron, trapezohedron, and hexoctahedron." — Ford, 1912

"The symmetry of the Pyritohedral class is as follows: The three crystal axes of binary symmetry; the four diagonal axes, each of which emerges in the middle of the octant, are axes of trigonal symmetry." — Ford, 1912

Symmetry of pyritohedral class

"The symmetry of the Pyritohedral class is as follows: The three crystal axes of binary symmetry; the…

"This form consists of twelve pentagonal-shaped faces, each of which intersects one crystallographic axis at unity, the second axis at some multiple, and is parallel to the third." — Ford, 1912

Pyritohedron

"This form consists of twelve pentagonal-shaped faces, each of which intersects one crystallographic…

"The diploid is a rare form found only in this class. It is composed of twenty-four faces which correspond to one-half the faces of a hexoctahedron." — Ford, 1912

Diploid

"The diploid is a rare form found only in this class. It is composed of twenty-four faces which correspond…

"A combination of cube and pyritohedron, in which it will be noted that the faces of the pyritohedron trunctuate unsymmetrically the edges of the cube." — Ford, 1912

Cube and pyritohedron

"A combination of cube and pyritohedron, in which it will be noted that the faces of the pyritohedron…

"Combiantion of pyritohedron and octahedron." — Ford, 1912

Octahedron and pyritohedron

"Combiantion of pyritohedron and octahedron." — Ford, 1912

"A combination of pyritohedron and octahedron." — Ford, 1912

Octahedron and pyritohedron

"A combination of pyritohedron and octahedron." — Ford, 1912

"A combination of pyritohedron and octahedron." — Ford, 1912

Pyritohedron and octahedron

"A combination of pyritohedron and octahedron." — Ford, 1912

"A cube trunctuated with pyritohedron and octahedron." — Ford, 1912

Pyritohedron, cube, and octahedron

"A cube trunctuated with pyritohedron and octahedron." — Ford, 1912

"A combination of cube and diploid." — Ford, 1912

Diploid and cube

"A combination of cube and diploid." — Ford, 1912

"The symmetry of this class is as follows: The three crystallographic axes are axes of binary symmetry; the four diagonal axes are axes of trigonal symmetry; there are six diagonal planes of symmetry." — Ford, 1912

Symmetry of tetrahedral class

"The symmetry of this class is as follows: The three crystallographic axes are axes of binary symmetry;…

"The tetrahedron is a form composed of four equilateral triangular faces, each of which intersects all of the crystallographic axes at equal lengths. It can be considered as derived from the octahedron of the Normal Class by the omission of the alternate faces and the extension of the others." — Ford, 1912

Positive tetrahedron

"The tetrahedron is a form composed of four equilateral triangular faces, each of which intersects all…

"The tetrahedron is a form composed of four equilateral triangular faces, each of which intersects all of the crystallographic axes at equal lengths. It can be considered as derived from the octahedron of the Normal Class by the omission of the alternate faces and the extension of the others. If the other four faces of the octahedron had been extended, the tetrahedron resulting would have had a different orientation, known as the negative tetrahedron." — Ford, 1912

Negative tetrahedron

"The tetrahedron is a form composed of four equilateral triangular faces, each of which intersects all…

"If a positive and negative tetrahedron occured together with equal development, the resulting crystal could not be distinguished from an octahedron, unless, as is usually the case, the faces of the two forms showed different lusters, etchings, or striations that would serve to differentiate them." — Ford, 1912

Positive and negative tetrahedrons

"If a positive and negative tetrahedron occured together with equal development, the resulting crystal…