When people see the Calendarium they think that they are looking at the Astronomical Clock. Actually the Clock is above it and was there first. The Calendarium was added around 80 years later. The first mention of the Calendarium is in 1490.
What Does It Do?
Although it is far less technical than the clock it’s still a fascinating piece of equipment but this part is all about Astrology. When you look at the clock it is going to tell you 1) the name of a saint or important religious person associated with that day (Czechs used this to identify a person’s Namesday) and 2) The current astrological sign according to the Roman calendar.
How Does The Calendarium Work?
The picture shows the detail of the Calendarium and you can see a few things.
1) the centre has castle turrets and a decoration around it. This part is fixed and the rest of what you see is a disc which rotates around this fixed point.
2) small circular pictures which depict the current zodiac sign.
3) larger circular pictures showing somebody performing an action.
4) a ring around the edge of the disc divided into daily parts with associated names.
5) a gold coloured pointer at the top of the disc (centre left in the first picture of the post).
So let’s take the day I took this picture. It was October 3rd 2018, a week after they formally unveiled the Old Town Hall building, Astronomical Clock and Calendarium after a 2-year renovation. So if you had looked up to the golden pointer you’ll see that the zodiac sign is Libra and the action sign above it corresponds to some task that should be performed in this period i.e. ploughing of land and sowing of crops to be harvested the following spring. At the top of the disc the golden pointer would be over that particular day and the name in the box is Bohumil. So in a Czech calendar this is Saint Bohumil’s day. And as a namesday, any man in the country called Bohumil would get a present from his friends i.e. usually a drink.
There are two other things on the Calendarium that might interest you. First are the pictures i.e. the combination of the zodiac sign and an associated action is replicated at another location. You’ll see the same at Prague Castle, on the south side of St Vitus Cathedral, on the metal gates of the steps to the south entry but in this case they are plaques made of bronze.
Second is the plate in the centre of the Calendarium. The three towers over an open gate is the small version of the Prague city coat of arms. You would not believe it but there are less than a dozen visible plates in the Old Town which show this version. Every other plate, including all the manhole covers, show the same picture but this time with an arm and sword in the gate. So if you want to know why you’re going to have to read the Prague Coat of Arms Story.