THE PRAGUE ORLOJ, THE CLOCK MENTIONED SINCE 1410

Today, The Grandma has received great news of one of her closest friends, Tina Picotes, who is visiting Prague. They have been talking about this beautiful city and about its attraction, the Prague Astronomical Clock or the Prague Orloj, a clock that was first mentioned on a day like today in 1410.

 

The Prague Astronomical Clock or Prague Orloj, in Czech Pražský orloj, is a medieval astronomical clock attached to the Old Town Hall in Prague, the capital of the Czech Republic.

The clock was first installed in 1410, making it the third-oldest astronomical clock in the world and the oldest clock still in operation.

The Orloj is mounted on the southern wall of Old Town Hall in the Old Town Square.

 

The clock mechanism has three main components -the astronomical dial, representing the position of the Sun and Moon in the sky and displaying various astronomical details; statues of various Catholic saints stand on either side of the clock; The Walk of the Apostles, an hourly show of moving Apostle figures and other sculptures, notably a figure of a skeleton that represents Death, striking the time; and a calendar dial with medallions representing the months.

According to local legend, the city will suffer if the clock is neglected and its good operation is placed in jeopardy; a ghost, mounted on the clock, was supposed to nod its head in confirmation. According to the legend, the only hope was represented by a boy born on New Year's night.

The oldest part of the Orloj, the mechanical clock and astronomical dial, dates back to 1410, when it was created by clockmaker Mikuláš of Kadaň and Charles University professor of mathematics and astronomy Jan Šindel.

More information: Prague

The first recorded mention of the clock was on 9 October 1410. Later, presumably around 1490, the calendar dial was added, and the clock facade was decorated with gothic sculptures.

Formerly, it was believed that the Orloj was constructed in 1490 by clock master Jan Růže, also called Hanuš; this is now known to be a historical mistake. A legend, recounted by Alois Jirásek, has it that the clockmaker Hanuš was blinded on the order of the Prague Councillors so that he could not repeat his work; in turn, he disabled the clock, and no one was able to repair it for the next hundred years.

In 1552, it was repaired by Jan Táborský (1500–1572), master clockmaker of Klokotská Hora, who also wrote a report of the clock where he mentioned Hanuš as the maker of this clock. This mistake, corrected by Zdeněk Horský, was due to an incorrect interpretation of records from the period.

The mistaken assumption that Hanuš was the maker is probably connected with his reconstruction of the Old Town Hall in the years 1470–1473. The clock stopped working many times in the centuries after 1552, and was repaired many times. The legend was used as the main plot in the animated film Goat story-The Old Prague Legends.

In 1629 or 1659 wooden statues were added, and figures of the Apostles were added after a major repair in 1787–1791. During the next major repair in the years 1865–1866 the golden figure of a crowing rooster was added.

The Orloj suffered heavy damage on 7 and especially 8 May 1945, during the Prague uprising, when the Nazis fired on the south-west side of the Old Town Square from several armoured vehicles in an unsuccessful attempt to destroy one of the centres of the uprising.

 

The hall and nearby buildings burned, along with the wooden sculptures on the clock and the calendar dial face made by Josef Mánes. After significant effort, the machinery was repaired, the wooden Apostles restored by Vojtěch Sucharda, and the Orloj started working again in 1948.

The Orloj was renovated in autumn 2005, when the statues and the lower calendar ring were restored. The wooden statues were covered with a net to keep pigeons away.

The last renovation of the astronomical clock was carried out from January to September 2018, following a reconstruction of the Old Town Tower. During the renovation, an electric clock mechanism that had been in operation since 1948 was replaced by an original mechanism from the 1860s.

The Orloj was taken down for reconstruction and replaced by a LED screen in early 2018, with the restoration works scheduled to last for the whole summer tourist season of 2018 and the restored actual Orloj eventually being back in service soon enough to commemorate the 100th anniversary of Czechoslovakia at the end of October 2018. With the reconstruction and restoration work completed, it resumed operations at 6 p.m. local time on 28 September 2018.

More information: Interesting Engineering

The astronomical dial is a form of mechanical astrolabe, a device used in medieval astronomy. Alternatively, one may consider the Orloj to be a primitive planetarium, displaying the current state of the universe.

The astronomical dial has a background that represents the standing Earth and sky, and surrounding it operate four main moving components: the zodiacal ring, an outer rotating ring, an icon representing the Sun, and an icon representing the Moon.

The background represents the Earth and the local view of the sky. The blue circle directly in the centre represents the Earth, and the upper blue is the portion of the sky which is above the horizon. The red and black areas indicate portions of the sky below the horizon. During the daytime, the Sun sits over the blue part of the background and at night it sits over the black. During dawn or dusk, the mechanical sun is positioned over the red part of the background.

Written on the eastern (left) part of the horizon is aurora (dawn in Latin) and ortus (rising). On the western (right) part is occasus (sunset), and crepusculum (twilight).

Golden Roman numerals at the outer edge of the blue circle are the timescale of a normal 24-hour day and indicate time in local Prague time, or Central European Time.

 

Curved golden lines dividing the blue part of the dial into 12 parts are marks for unequal hours. These hours are defined as 1/12 of the time between sunrise and sunset, and vary as the days grow longer or shorter during the year. Inside the large black outer circle lies another movable circle marked with the signs of the zodiac, which indicates the location of the Sun on the ecliptic. The signs are shown in anticlockwise order. In the photograph accompanying this section, the Sun is currently moving anticlockwise from Cancer into Leo.

The displacement of the zodiac circle results from the use of a stereographic projection of the ecliptic plane using the North Pole as the basis of the projection. This is commonly seen in astronomical clocks of the period.

The small golden star shows the position of the vernal equinox, and sidereal time can be read on the scale with golden Roman numerals. The zodiac is on the 366-tooth gear inside the machine. This gear is connected to the sun gear and the moon gear by a 24-tooth gear.

At the outer edge of the clock, golden Schwabacher numerals are set on a black background. These numbers indicate Old Czech Time or Italian hours, with 24 indicating the time of sunset, which varies during the year from as early as 16:00 in winter to 20:16 in summer. This ring moves back and forth during the year to coincide with the time of sunset. 

More information: Discover Walks

The golden Sun moves around the zodiacal circle, thus showing its position on the ecliptic. The sun is attached to an arm with a golden hand, and together they show the time in three different ways:

-The position of the golden hand over the Roman numerals on the background indicates the time in local Prague time.

-The position of the Sun over the curved golden lines indicates the time in unequal hours.

-The position of the golden hand over the outer ring indicates the hours passed after sunset in Old Czech Time.

Additionally, the distance of the Sun from the centre of the dial shows the time of sunrise and sunset. The Sun and its hand are on the 365-tooth gear inside the machine.

The movement of the Moon on the ecliptic is shown similarly to that of the Sun, although the speed is much faster, due to the Moon's orbit around the Earth. The Moon's arm is on the 379-tooth gear inside the clock machine.

The half-silvered, half-black sphere of the moon also shows the Lunar phase. The Moon has a 57-tooth gear inside its sphere, and is slowly rotated by a screw-thread attached to a weight, advancing two teeth per day. This movement, powered only by gravity, makes the Orloj unique in the world among astronomical clocks showing the phases of the Moon. The mechanism was created by an unknown maker, probably in the mid-17th century. Unlike the original device, the construction of which was described in a report from 1570, this mechanism produces much smaller deviation from the actual lunar phase of about one day in five years.

More information: Atlas Obscura

I had travelled to a lot of cities in Europe before,
but Prague was special.
It held a mysterious attraction for me for
during the time I was there.

Arfi Lamba