Illustration used to show how to pass a circumference through any three points not in the same straight line.

Construction Of Circumference

Illustration used to show how to pass a circumference through any three points not in the same straight…

Illustration used to construct a triangle , given the perimeter, one angle, and the altitude from the vertex of the given angle.

Construction of a Triangle Given Perimeter, Angle, Altitude

Illustration used to construct a triangle , given the perimeter, one angle, and the altitude from the…

"A screw cut on a solid, of such form that if any plane be taken through its longitudinal axis, the intersections of the plane by the perimeter are arcs of the pitch-circle of a wheel into which the screw is intended to work. It is so named from having been first employed by Mr. Hindley of York in England." —Whitney, 1889
<p>The hourglass shape of the screw increases the bearing area and therefore reduces wear.

Hindley's Screw

"A screw cut on a solid, of such form that if any plane be taken through its longitudinal axis, the…

Illustration to show that if from any point in the base of an isosceles triangle parallels to the legs are drawn, a parallelogram is formed whose perimeter is constant, being equal to the sum of the legs of the triangle.

Isosceles Triangle With Parallelogram inside

Illustration to show that if from any point in the base of an isosceles triangle parallels to the legs…