 Associated with the ring is a rayed apparent-sun emblem whose supporting arm system moves to and fro relative to a main mean-motion arm by an amount corresponding to the equation of time, and also radially to represent changes in the sun's declination.Sun-emblem and horizon-plate therefore combine to show the times of the sun's rising, southing, and setting throughout the year and, by means of the 'rays', the extent of the twilight.To complete the front dial display, two sets of curved wires are mounted in front of the planisphere.