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"A large nail or pin, generally of iron. The larger forms of spikes, particularly railroad spikes, are chisel-pointed, and have a head or fang projecting to one side to bite the rail. Spikes are also made split, barbed, grooved, and of other shapes." &mdash;Whitney, 1889 <p>Illustration of two forked spikes. When driven into wood, the points spread and hook into the wood.

Forked Spikes

"A large nail or pin, generally of iron. The larger forms of spikes, particularly railroad spikes, are…

Illustration of a how to construct a square equivalent to the sum of two given squares.

Square Constructed to be Equal to the Sum of Two Given Squares

Illustration of a how to construct a square equivalent to the sum of two given squares.

Illustration of a how to construct a square equivalent to the difference of two given squares.

Square Constructed to be Equal to the Difference of Two Given Squares

Illustration of a how to construct a square equivalent to the difference of two given squares.

Illustration used to show how to bisect a straight line.

Bisect A Straight Line

Illustration used to show how to bisect a straight line.

Illustration used to show how "to construct a tangent to a circle from a point outside."

Construction of a Tangent to a Circle

Illustration used to show how "to construct a tangent to a circle from a point outside."

Pattern that can be cut out and folded to construct a regular tetrahedron. Fold on the dotted lines, and keep the edges in contact by the glued strips of paper.

Pattern for Tetrahedron

Pattern that can be cut out and folded to construct a regular tetrahedron. Fold on the dotted lines,…

A thin flat slab of fired clay used for roofing

Roofing Tile

A thin flat slab of fired clay used for roofing

Illustration showing ambiguous case when the solution is not a triangle using law of sines.

Ambiguous Case of Law of Sines Triangle

Illustration showing ambiguous case when the solution is not a triangle using law of sines.

Triangle construction when given two angles and the included side.

Triangle Construction When Given 2 Angles and Included Side

Triangle construction when given two angles and the included side.

Development of a triangular pyramid.

Development of a Triangular Pyramid

Development of a triangular pyramid.

Plan and elevation of a triangular pyramid.

Plan and Elevation of a Triangular Pyramid

Plan and elevation of a triangular pyramid.

Projections and development of a truncated cylinder.

Projections and Development of a Truncated Cylinder

Projections and development of a truncated cylinder.