Article of the month July

Antique or unequal hours

In antiquity, a time system quite different from ours was in use.
The daylight period from sunrise to sunset was divided in twelve hours.
Because on a summer day the sun is longer above the horizon then on a winter day, a summer hour would likewise be longer than a winter hour.
The table below shows this for a latitude of 52 degrees.
Note that at the beginning of spring and autumn, an ancient hour is just as long as an "ordinary" hour, because on those days the daylight period is twelve modern hours long.

Start of season	Daylight period in modern hours	Antique hour in modern hours
Spring	12:00	1:00
Summer	16:30	1:23
Fall	12:00	1:00
Winter	7:30	0:38

Here you see a horizontal sundial for a latitude of 52 degrees, showing ancient hours.
It is a point dial. The red line shows the length of the gnomon.
Exactly calculated, as possible today, the hour lines should be curved. This was not known in antiquity, and the hour lines were always drawn straight. Here, too, the lines are shown as straight..
On middle and low latitudes, the deviation from a straight line is, as a matter of fact, but minimal.

In antiquity, perception of time was entirely differently from what it is now.
We think in points in time: it is 9:38 or it is 16:12 etcetera.
In former days, one thought more in time periods: we are in the first hour or we are in the eighth hour.
Thus, the afternoon starts when the sixth hour is past and the seventh hour starts.
This also explains why the hour numerals in the sundial above are not on the hour lines, but in between.

The Bible mentions antique hours in various places, and the new Dutch translation of 2004 has kept it this way.