The Ellipsograph, a Mechanism for Constructing an Ellipse
This Demonstration shows a top view of an ellipsograph, a mechanism for constructing the ellipse . The points and slide along the and axes. The distance between them is and the distance between and is .
 D. Wells, The Penguin Dictionary of Curious and Interesting Geometry, New York: Penguin Books, 1991 p. 66.
"The Ellipsograph, a Mechanism for Constructing an Ellipse"
Wolfram Demonstrations Project
Published: April 18 2013