The verge (or crown wheel) escapement is the earliest known type of mechanical escapement, the mechanism in a mechanical clock that controls its rate by allowing the gear train to advance at regular intervals or 'ticks'.he verge (or crown wheel) escapement is the earliest known type of mechanical escapement, the mechanism in a mechanical clock that controls its rate by allowing the gear train to advance at regular intervals or 'ticks'.
You need the foci for some construction methods. Just draw radii of length a from the ends of the minor axis. Given the foci, however, you can't uniquely determine the axes. You need additional information such as the length of one axis.
You can change the position of the two focus points (F1, F2). Also drag the point on the ellipse and observe that the sum of the lengths of the lines that meet there is constant. An ellipse looks like a circle that has been squashed into an oval. Like a circle, an ellipse is a type of line. Imagine a straight line segment that is bent around until its ends join. Then shape that loop until it is an ellipse - a sort of 'squashed circle' like the one above.