Calendar indicators have appeared on clocks since the late 17th century. Some clocks displayed the days of the month on the outside edge of their dials, while clocks that were large enough for two dials used one to show the time and another to mark the day of a particular month. The most complicated vintage calendar clocks also indicated moon phases, high and low tides, the days of the week, and the year, with the best clocks even correcting...Continue Reading