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.
The perpendicular bisector of a chord always passes through the center of the circle. In the figure at the top of the page, click Show Right Bisector. Then move one of the points P,Q around and see that this is always so. This can be used to find the center of a circle: draw one chord and its right bisector. The center must be somewhere along this line. Repeat this and the two bisectors will meet at the center of the circle.