The portable sundial of Parmenion

Three articulated rings hung at vertical position with the external ring oriented East-West. The central ring consisted of two semicircles, bearing 2 pairs of engravings of 7 grooves defining the months (zodiacs) for 4 different latitudes-towns). The inner ring bore a hole on its periphery, while around it there were engravings dividing it into 12 equal parts which defined the 12 hours. During the clock operation, the semicircle with the data of the area was turned by 90º and the inner ring was placed on the current month; thus a bright spot indicated the hour on the opposite side. The clock could also be used at midday of the equinoxes in order to find the latitude of a place, the azimuth and the star height. (Fractions of the instrument were found in the Octagon of Philippi).