Unfortunately, we don't know of any way to modify a real life pin-and- string device to draw these ovals of Cassini. But what can't be done in the real world can easily be done in the virtual world! Our computer simulation of the pin-and-string device has no trouble with Cassini's definition.
In this drawing, you can
When you drag in the area around the oval, the lengths of the two segments are shown at upper left, and their product appears below them, colored in red if you're on (or outside) the oval.
Return to The Shape of an Egg, or the main EggMath page.