Construction Of An Ellipse
Illustrations used to construct an ellipse. Fig. 59 shows a compass at C used to strike a circle. Where the circle intersects the line at D and B, place pins. These pins represent the foci of the ellipse. Use a cord and a pencil to draw the ellipse as shown in figure 60. This illustrates the definition of an ellipse.
Ethel Traphagen The Wiley Technical Series Costume Design and illustration (New York, NY: John Wiley & Sons, Inc., 1918)
Courtesy the private collection of Roy Winkelman