Greece, Ancient Greek Technology

Vertical sundial of eastern orientation. Aristarchus's disk. Photo : Augusta Stylianou Artist

Vertical sundials of eastern orientation
A vertical net orientated to the East with 6 engraved hour lines and three curves indicates with the help of the shadow trace from the horizontal (vertical to the net) gnomon tip, 5 unequal (depending on the season) daily hours after the sunrise (1st, 2nd, erd, 4th and 5th). The horizontal hour line at the height of the gnomon indicates the sunset. The higher curve indicates the course of the sun's shadow at the winter solstice, the lower at the summer solstice and the middle straight line at the equinoxes.