Article of the month February

Horizontal card dial

for the IX-th antique hour

The photograph shows a small paper sundial that was found in an old book, in Italy, some years ago.
It is a horizontal altitude measuring sundial for 45 degrees latitude.

On the spot marked “Stili longitudo”, a gnomon is placed of the length indicated in the drawing.
Across the card are date scales.
The sundial is made exclusively for “HORA IX PLANETARIA”. In this case, this means the IX-th antique hour. That is exactly in the middle of the afternoon.

In the first half of the afternoon, the card dial is placed horizontally and rotated so that the shadow of the gnomon falls over the actual date.
As time progresses, the card is turned little by little until the shadow of the terminus of the gnomon falls on the date. It is then the IX-th antique hour.

A Latin text explains the operation of this limited little sundial.

Horam nonam planetarium hic in pagina exhibeo, que solaris radii auxilio indicabit tempus recitandi pridie matutinum iuxta privileg(ium).

On this page I show the ninth antique hour, which, using the rays of the sun, indicates the time to say matins on the previous day, in accordance with the privilege.

Matins used to be said when it was still night. Old and sickly monks were given the privilege of saying matins on the previous day, after the ninth hour.