2.3

Modern Sundials

The duration of daytime changes in the course of the year, which is made visible by mechanical clocks. This is why, in the beginning, they included a double time display. An eccentric circle and lines on the dial indicated the canonical hours, but at the same time, the device also featured a sun hand indicating regular modern hours on the outer circle.

But how can you build sundials which indicate regular hours? The solution is to adjust the rod in parallel to the axis of the earth. This allows for a calculation of scales which show equal hours, both in summer and winter.

Time specifications in equal hours increasingly imposed themselves in everyday life. Now the day began at midnight, as the moment of midnight does not depend on the length of the day. This also changed the way of counting the hours: While in the past, the noon line was between the sixth and the seventh canonical hour, it was now associated with the number twelve.