A subsidiary dial, usually in the twelve o'clock position on a marine chronometer or precision pocket watch, which indicates the degree to which the mainspring is wound at the time of observation. It was usually fitted when failure to wind the timekeeper would have serious consequences, as on a chronometer used for longitude determination. On a fusee timepiece it consists of a pinion placed on the fusee arbour which moves a high-numbered wheel with an arbour carrying a hand, so arranged that a full run of the spring will carry the hand somewhat less than 360? On going-barrel pieces it is much more complicated and sometimes employs planetary gearing.