Ellipsograph of Leonardo da Vinci.
It’s developed from ellipse mechanism
http://www.youtube.com/watch?v=FoO2LIYLPEc
Stationary red pencil draws on moving disk an ellipse when violet crank is turned.
Alter distance OA for various ellipse eccentricities. When OA = 0, a circle is gotten.
Alter position of the pencil for various sizes of drawn ellipses (the video last scene).
آی-ویدئو