Elements of plane and solid free-hand geometrical drawing, with lettering; and some elements of geometrical ornamental design, including the principals of harmonic angular ratios, etc. In three parts ... for draughtsmen and artisans; and teachers and students of industrial and mechanical drawing (1878)
Warren, S. Edward (Samuel Edward), 1831-1909 · New York, J. Wiley & sons · leaf 156
1. The circle is a curve, all of whose points are at a uni-form distance, called the radius, from a fixed point within it,called its centre. The ellipse is a curve, such that the sum of the distances ofeach of its points from two fixed points within it is uniform,and equal to the longest line which… … from two foci, F and F;, is always the same, and equal to thelongest chord, or transverse axis, AB, of the curve. Manydifferently shaped ellipses, wide or narrow, may thus be formedaccording to the distance apart of F and F, while AB remainsof fixed length. Pins being fixed at F and F, and a firm…
Geometrical drawing · Mechanical drawing
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
