Date: Oct 11, 2013 5:10 PM
Author: Rich Delaney
Subject: curve construction

One can construct an ellipse as follows: 
pin 2 thumbtacks into a sheet, loop a string
(tied at the ends) loosely around them, pull
it taut, draw the ellipse with a pencil; the
sum of the distances etc.

Are there similar methods to draw a parabola
and hyperbola?