Geometric Construction

The geometric construction of an ellipse can easily be accomplished with some very simple tools: a piece of string, a pencil, two pins, and a piece of paper. Simply stick the two pieces of string into the piece of paper using the two pins. Pull the string tight (using the pencil) until a triangle is built with the pencil and the two pins as vertices. Now, keeping the string pulled tight, move the pencil around until the ellipse is traced out. (See the enclosed FIGURE E2.)