Rulers of the Hours
Running vertically on either side of the clock are boards painted with the gods/planets that rule the day; these change at midnight. They ascend on the right and descend on the left and the ruler of the first hour (labeled IN 1 HO REGIT) is shown on the bottom right. This is the ruler of the day, after which the day is named. When this picture was taken it was a Wednesday, and indeed Mercury = the Germanic Wotan, the ruler of Wednesday.