From The Burning Hand
A Gansberg Clock (or Gansberg Device) is a term now used for any machine that indicates the passing of 'tween times. These are times where the walls of the gaol are at their thinnest, and strange events can happen naturally, or be forced by the hand of humans.
The first such device was a mantle-clock devised by Elias Gansberg in the 1930s. As well as telling the time, and showing the day, month and date, three other dials set into its face showed the phase of the moon, the daily cycle of dawn, noon, dusk and midnight, and the solar holidays on the wheel of the year.