Some of you long-time readers know that I sometimes write about things astronomical and that I have mentioned the fascinating Jesuit mathematician Christopher Clavius (+1612), who worked out the reform of the calendar for Pope Gregory XIII.
For your Just Too Cool file, or at least for my Just Too Cool file, the Vatican Post has put out a stamp with none other than Christopher Clavius!
Here is a shot from the tomb of the aforementioned Roman Pontiff, depicting the moment Clavius presented his scheme for the reformation of the Julian calendar.
Clavius did all his calculations without the use of the decimal point! The decimal point, or mark, was known at the time, but it wasn’t commonly used. Clavius would pioneer it’s use in later work.
I think it is interesting that of all the things Gregory XIII could have selected for his monument, this is the moment.
BTW… note the guy to the far left, with the eye-glasses!
Clavius is one of many Jesuit mathematicians who have a crater on the Moon named after them.