The classical mode of time-telling is the familiar circular fashion where a pair of hands traces a ring of numbers of indexes, but there is more than one way to tell the time (or date).
One alternative that watchmakers have been known to employ is the retrograde indicator, often to a creative effect. A retrograde indicator is based on a system of snails, gear wheels, and spring that moves a single hand from one point to another in an arc. As soon as the hand reaches the end of the arc, it snaps back instantaneously to the starting position and continues sweeping along until it reaches the end again, and again it snaps back to the start. This goes on repeatedly in an endless choreography.
The retrograde display is applicable to anything from hours and minutes, even seconds, or date and day, which makes it an ideal candidate for watchmakers to creatively tell the time.
There are also functional uses for the retrograde display. Using a combination of sub-dials and retrograde displays allow a watchmaker to optimise the limited space available on the dial. It would not be possible for all the complications on a watch like the Aeternitas Mega, for example, to be displayed solely on sub-dials. Retrograde indicators also add much visual interest to a watch. Franck Muller’s legendary Take Your Time is a prime example of creativity in the use of the retrograde indicator.