Geometrical Conic Sections - An Elementary Treatise in Which the Conic Sections Are Defined as the Plane Sections of a Cone, and Treated by the Method of Projections #268821

It is hoped these may be thought sufficient reasons for departing from the definition which has been in use of late years. I have retained the proof of the constancy of the ratio of the rectangles under the segments of intersecting chords in constant directions (chap. V. Given by Dean Hamilton in his treatise published in 1773, as an improving and interesting study and one that is in harmony with the scheme of this work.