6 Greenhill Gardens,
6 / 2 / 63
My dear Sir,
It is easy to show by analytic geometry that the locus of any point in a line of constant length whose ends move in two intersecting lines is an ellipse; but I think you will be pleased with the following geometrical proof.
[diagram] When the circle OAB rolls within another of double size, the points A & B describe diameters OA' & OB' & AB is of constant length; Also any point of the circle’s area, and therefore any point of AB, describes an Ellipse.
Yours very truly
P. Guthrie Tait.
H. F. Talbot Esqre
Please cite as “TALBOT6252,” in Ɛpsilon: accessed on