The Calendar is the bottom part of the Orloj with month symbols painted by Josef Manes in 1805. The originals of these can be found on the sides of the stairway of the Prague Museum of History. See Orloj history below for more.

The third gearing the Moon's pointer rotates accordingly with the mean apparent motion of the Moon.

The second gears the indicator of the Sun and rotates once a mean solar day.

The first of these gearing the zodiac and the indicator with the asterisk rotates once a sidereal day.

The Clockwork In the clockwork there are three great co-axial wheels of the same diameter, driven by the same pinion, with 365, 366 and 379 cogs.

Three pointers rotate around this dial: one for the Sun one for the Moon the third is for zodiac

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 dial shows three mutually independent movements: the mean revolutions of the Sun, the mean revolutions of the Moon and the apparent revolutions of the stars (the ecliptic, to be more precise).

The Sphere or clock dial is the central part of the Orloj and represents the astronomical phenomena such as sunrise and sunset, ancient Czech and present day time, movements of the Sun and the Moon and other relative celestial configurations.

Basic concept

The concept of the Orloj as an astronomical clock, was to represent the course of the sun and stars just like the real thing and the main task was to show with precision the exact point in the afternoon when the sun was at it's highest.

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).

In times when clock works were imprecise in maintaining their continuous precision, it was necessary to keep correcting them, comparing clocks with other clocks and the best way to do this was according to the then sun clock measurements - the sun dials.

Initially- clocks, the Orloj included, were 'tuned' according to the local sun position and had to be continually 'corrected' accordingly.

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.

These were the basic starting phases of the Orloj.

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.

It is unique in being the oldest of those where the original clockwork has been in operation from the beginning to the present time for six centuries, and even the astronomical dial shaped like an astrolabe survives in the original form.

Interestingly, the Clock initially showed exclusively astronomical data and there were no irrelevant little mechanical figures to entertain the common people but only "the pure art of astronomy".

Legends

There are many legends surrounding this Clock, the most famous of which is about the master clockmaker Hanus himself It is said that the Old Town Councilors had his eyes burnt out with a hot poker, so that he would not be able to build another such instrument elsewhere, which could overshadow the beauty and the fame of the Prague Clock. Master Hanus then allegedly asked his apprentice to take him to the clock, which he deliberately damaged so seriously, that nobody could repair it. Those who tried either died in doing so, or have gone mad. In reality, the Clock was not very reliable and often did not work, in spite of extensive repairs. A further legend gives the Skeleton magical power of foretelling the future and says that if the clock is left damaged for a long time, hard times will result for the Czech nation.



Orloj History. - more or less....

The original lone tower housing the present day Orloj was built in 1381.



The initial clock was installed in 1410 by clockmaker Mikulas of Kadan with the astronomer and professor of mathematics at Prague Charles University - Jan (Ondrejuv) Sindel (see below about him). The craftsman Hanus Carolinum. - originally accredited with the Orloj concept actually only did some repairs in 1490 and in this second phase is reputed to have added the calendar dial under the astronomical dial. According the legend - the councilors blinded Hanus so that he could not recreate another similar clock in any other City. Before he died, the blind Hanus climbed the tower of the clock and took revenge by damaging it and causing it to stop.



At that time - the entire facade of the Orloj was richly decorated with striking Vladislav Gothic - which is the Czech equivalent of Flamboyant Gothic - stone sculptures. 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. Between 1552 and 1560 major repairs were done by Jan Taborsky. 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 the following years the Orloj was neglected and damaged and at the beginning of the 17th century - around 1613 was repaired by watchmaker Kristof Svarcpach After that the Orloj kept running from bad to worse until it stopped completely. Small repairs were undertaken after the thirty year war (1618-1648) in 1648 but got the Orloj running for only a few weeks at a time. Towards the end of the 17th century the new statues were added - moving statues in particular the Death that tolls the bell by the side of the astronomical dial and immobile ones alongside the calendar dial were added, but there was no money for major repairs and worse still, no capable watchmaker was found to do more technical repairs. Worse to come - in 1787 the whole mechanism nearly went for sale as scrap iron. Watchmaker Jan Landesberg partially came to the rescue trying to repair the mechanical part ... but he was not very successful. He managed to repair the clock part but the astronomical calendar and other parts of the mechanism had to wait another hundred years Major restructuring of the whole Orloj in the 1860s gave it the present day aspect. In 1861, when the clock stopped working the Orloj was up for sale once again as the 'Town' didn't have the 4000 gold pieces necessary to save and repair it. Fortunately , a collective sum was raised and the Orloj was not sold.

Unfortunately in 1864 due to a fire the Apostles statues from Eduard Veveleho were destroyed. In 1865, Jan Holoub under the supervision of watchmaker Ludvìk Hainze from Prague and under advice from F. Bohm repaired Orloj. During this repair (end 1865) a new calendar disc was installed, made by the well-known Czech painter Josef Manes. The cycle of twelve medallions of the Months and the same number of medallions of zodiacal signs is one of his culminating works. These today have been replaced by a copy from Bohumil Cilli and the originals are in the City Museum. On the 4th of January 1866 Alexander Dumas, on his way to Dresden with his daughter, stopped in Prague and paid a visit to the Orloj. On the 18th of August 1866 the Orloj was unveiled amidst festivities as 'he' had been finally repaired to the state that we know today only to be closed down to have all the mechanisms re-lubricated , the last defects repaired and mainly to connect it all together so that the calendar plate would also work. Finally on the 14 th September 1866 the Orloj was functioning as everyone in the past 400+ years involved had envisioned. From this time the Orloj was maintained by Ludvik Heinz, after whose death in 1874 the maintenance was done by his son Ludvik Heinz and from the year 1901 in turn his nephew - another Ludvik Heiz. Happy ending ? Not quite. In 1945 the whole structure - tower, mechanism - was damaged during the final phases of WWII and the Prague uprising. During the fighting in Prague the Nazis directed artillery fire at the Old Town Hall and even used fire grenades. The entire building burnt down and with it the complete City archives burnt to ashes. Nevertheless, a number of self-sacrificing persons managed to repair the authentic old clockwork. The original figures of the Apostles have been replaced by the creations of the woodcarver Vojtech Sucharda after the end of the Second World War. The Orloj was renewed in every respect in its original form three years later in 1948- on the 1st of July, and once again started to function and to chime with new statues and new versions (copies) of the Mànes calendar in place. The last main repair was undertaken in the spring of 1979

One of the Keepers of Orloj

Otakar Zamecnik