Precision dating members
The important exceptions are the sculptures flanking the astronomical dial and mask and figures on its architrave which were created at the beginning of the 15th century by members of the masonic lodge of stonemasons and sculptors led by Peter Parler.
Around 1566 the Orloj was completely mechanized and the tasks of the Orlojners were to wind all four mechanisms, to monitor the working of the clock and to 'fix' any errors or breakdowns when the mechanisms went out of sync.
In fact there were two sun dials on both sides of the location of the Orloj clock and the remains of these on the Old Town Hall walls were visible until 1911 when they were removed.
As the development of clockwork mechanisms progressed, soon clocks could run with more precision than sun dials and were based on the central local sun position. Astronomers then came to worry about time precision by synchronizing the precision of clocks according to star configurations and their movement around the Earth.
Further developments in clockwork mechanisms made it necessary or viable to be able to divide time into units.
The Orloj, also known as The Prague Astronomical Clock is one of the oldest European clocks of its kind (the first ever originated in Padua in 1344 and a second in Strasbourg in 1354) and continues to hold its exceptional position.
This is why the Orloj was always timed to the real sun time using sun dials (vertical sticks dependant on sun and shadow to measure time).
The horizon is indicated by the boundary of blue and red; in the left part the day-break (AVRORA) with a rising border (ORTVS), in the right part the twilight (CREPVSCVLVM) with a setting border (OCCASVS).
The dark circle at the bottom displays the astronomical night.
The second gears the indicator of the Sun and rotates once a mean solar day.
The third gearing the Moon's pointer rotates accordingly with the mean apparent motion of the Moon.