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.
focal point. n. 1. (General Physics) Also called: principal focus or focus the point on the axis of a lens or mirror to which parallel rays of light converge or from which they appear to diverge after refraction or reflection. 2. a central point of attention or interest.