The Calendar Clock

This is the first time I had seen a clock's plate with 31 numbers. Take the initiative to learn more of this Spanish artifact as seen in Intramuros Philippines. The 31 numbers represent the days of the month, it automatically changed in its course of rotation based on the day of the month like the 28th, 30th and 31st. For the antique collectors, the interest will take the chance of obtaining a unique calendar clock with 31 numbers in the outermost part of the plate.