Astronomy for the use of schools and academies (1882)
Gillet, J. A. (Joseph Anthony), 1837-1908, Rolfe, W. J. (William James), 1827-1910 · New York : Potter, Ainsworth, & Co. · leaf 63
nplaced against the string, and carried around, as shown inthe figure. The curve described by the pencil is an ellipse.The two points F and F are the foci of the ellipse : thesum of the distances of these two points from every pointon the curve is equal to the length of the string. Whenhalf of the… … centre of the ellipse ; A A is the major axis of the ellipse,and CD is the minor axis. 43. The Fccentricity of the Fllipse. — The ratio of thedistance between the two foci to the major axis of theellipse is called the eccentricity of the ellipse. The greater the distance between the twofoci,…
Astronomy
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
![An illustration from L'optique divisée en trois livres : ou, l'On démontre d'une maniere aisée tout ce qui regarde 1. la propagation & les proprietez de la lumiere. 2. La vision. 3. La figure & la disposition des verres qui servent à la perfefectionner [sic] (1682)](https://img.insideoutlibrary.com/img/200/ia-loptiquedivise00ango-341-38.webp)
