The astronomical clock in Münster cathedral

@Eckhard

Published in 

Mittelalter

 · 23 Aug 2023

CHRONOLOGICAL TABLE

TECHNICAL DETAILS

PLEASE NOTE

The numbers in the margin of this booklet refer to illustrations.
The numbers in brackets in the text refer to the corresponding numbers of the schematic diagram at the end of this booklet.

1 - The astronomical clock

HISTORY OF THE CATHEDRAL CLOCK

The astronomical clock in Münster cathedral was completed in 1540 and is the second ornamental clock here. One had already been erected here in 1408 by the Cistercian monk Friedrich from the monastery in Hude near Delmenhorst.

No drawing has been handed down to show us what that clock looked like, but, like other ornamental clocks of the 14^th and 15^th century, it will doubtless have consisted of three parts: the procession of the Three Magi, the clock face, and the calendar. In 1534-1535 this clock became the victim of the Anabaptist disturbances and was completely destroyed

The disturbances had hardly died down when the construction of the present clock began. It is the only monumental clock to have survived more than four centuries and which shows the orbit of the planets and the movement of the fixed stars as well as the course of the sun and moon. Three men from the Aachen-Jülich area were responsible for the calculations and their realization: the mathematician and printer Dietrich Tzwyvel, the Friar and cathedral preacher Johannes Aquensis, and the smith Nikolaus Windemaker. The whole conception of the clock with the calculations for the mechanisms which drive the sun, moon and planets, the fixed stars, the calendar, the Three Magi, the striking mechanisms and the carillon were all their work. The clock was probably regulated by a foliot balance consisting of a beam and spindle with two pallets.

Neither the extremely sensitive mechanism of the balance nor the soft wrought iron of the wheels could stand the strain put on them for an indefinite period of time. According to the records of the chapter of the cathedral, major repairs were becoming frequently necessary. In 1696 a new mechanism was put into the clock. In the meantime Galilei and Huygens had, independently of each other, discovered the isochronism of the pendulum; and a pendulum with cycloid and spindle was used in the mechanism of 1696.

When, at the end of the 18^th century, ever louder complaints about the poor running of the clock were to be heard and the repairs became more frequent and expensive, the dean of the cathedral, von Spiegel, found a drastic solution to the problem: he ordered a pin-wheel escapement with a 4m long pendulum to be built into the clock. The result was that each swing of the pendulum was accompanied by a loud noise as a pin of the pin-wheel struck against the edge of the long scissor-shaped anchor. This and signs of wear on other parts of the clock made the condition of the clock deteriorate more and more.

2 - The clock face

The cathedral clock would have been completely ruined had it not been for the intervention of the Münster editor Peter Werland, who made every effort in the 1920s to ensure the renovation of the clock. A lottery raised money for a large part of the costs. In 1930 the new factory for church clocks and machinery Friedrich E. Korfhage in Buer near Osna-brück was able to supply a new mechanism for the clock.

This was of the standard of a modern church clock but with several modifications necessary for the special features that distinguish this clock from a normal church clock.

DESCRIPTION OF THE CLOCK

The Astrolabe

Above the great clock face, which forms the central part of the clock, is an inscription (1) in a late Gothic frame. The inscription is in medieval Latin and explains the many functions of the clock. It can be translated as follows:
On this movable clock you can see amongst many other things the following: The times of the equal and unequal hours: The mean course of the planets: The ascending and descending sign of the zodiac: And the rising and falling of several fixed stars. Also, on both sides of this work, the ruling planets of the astronomical hours. Above, the procession of the Three Magi. Below, the calendar of the movable feasts. These features refer to elements from ecclesiastical and secular life of the 16th century, a time when astrology played an important role.

This inscription, the large automatic astrolabe in the centre of the clock (3) and the tables of planets (9) to the right and left of the clock face are all enclosed in a broad painted frame.

Before taking a closer look at the astrolabe, we should first point out the four white plates (2) on the painted frame. Here we can see the cardinal points of the compass. As we look at the clock, the East (oriens) is on the right-hand side; that is where the sun rises each day. On the left is the West (occidens), where the sun sets. At midday the sun is in the South (meridies), directly above us in the sky, which is why the South has been placed at the top of this clock, contrary to the usual manner of representation. At midnight the sun is below the horizon in the North (septentrio), and so we can find the North on the lower edge of the frame.

3 - The hands of the clock

Astrolabe (3) was the medieval term for astronomical measuring devices. They were made in several sizes and some were even small enough to be carried in the pocket. Every astrolabe has four parts: the engraved background, the mater; the planisphere, a fixed but interchangeable plate on which the courses of the most important celestial bodies were drawn; the rete, a circular map of the stars; and finally, a sighting device, with which one could locate the position of stars.

There are two important modifications to the astrolabe. on this cathedral clock. Firstly, a map of the world has been painted on the planisphere and its system of circles of altitude. Secondly, the clock needs no sighting device; no stars have to be sighted to adjust the hands. On the contrary, the hands of the clock automatically show the course of the stars and thus allow a direct reading.

Because the clock remains in one place, only one planisphere is needed, namely that of Münster. For this very reason the planisphere could be painted directly onto the background of the clock, namely the mater. The centre of the face, through which the axle of the mechanism runs, is the celestial North Pole. The rings have been drawn around the North Pole: the (northern) Tropic of Cancer, the Equator (represented by a red ring one centimeter in width), and the (southern) Tropic of Capricorn. The vertical line through the centre is the North-South line of longitude, the Münster meridian. The horizontal line through the Pole has no astronomical significance.

To the south, that is above the centre of the face, the Münster zenith lies on the North-South line of longitude; this is the point in the sky that is directly above the observer.

Around this point are the circles of altitude for Münster at intervals of 15°; at 0° is the Münster horizon, also called the oblique horizon. This line divides the Münster sky into two parts, namely visible and not visible. Stars above the oblique horizon are visible in Münster, and those below the oblique horizon are not visible. If the course of a star crosses the horizon to the right of the meridian, then the star has risen in Münster; if it crosses the horizon to the left of the meridian, then it has fallen.

Three vertical circular arcs run through the Münster zenith to the horizon; along with the North-South meridian they represent the eight main points of the compass.

A further group of lines can be seen where the meridian crosses the Münster horizon. Twelve arcs divide the planis-phere into twelve sections, of which six are above and six below the horizon. They are numbered 1-12 and represent the twelve astrological houses, which were said to influence our daily lives.

4 - The planisphere with a map of the world

There are also arcs running from east to west through north, numbered I to XII. These refer to the unequal hours of the night. Until clocks as we know them today with trains of wheels were invented, the long winter nights and the shorter summer nights were all divided into twelve parts of equal length, and the day was also divided in the same way.

In the 16^th century the times of prayer followed this system as well.

The system of circles of altitude is not only important for the astrolabe but also has significance for the map of the world painted on the clock face. This map was made shortly before 1670, and the system of lines is important for its layout. The celestial North Pole became the terrestrial North Pole, and the celestial Equator and Tropics could be used as the corresponding lines for the earth. The circles of altitude for Münster were also useful for locating geographical points on the map of the world. As the positions of North and South (but not of East and West) have been changed on the clock to depict the daily course of the sun, the map of the world also had to be adjusted accordingly. The result was that the map had to be painted as a mirror image. The painter is said to have been Henrich Schmidts from Münster. The map is typical of the 17^th century and is adapted from the map of the world by the Dutch cartographer Wilhelm Jansson Blau (1571-1638), a map which came to Münster during the peace negotiations at the end of the Thirty Years War. Although the map is drawn very freely, we can recognize several features. Five oceans are named: MARE DEL ZUR (South Sea = Pacific Ocean), MAR DI INDIA, MARE DEL NORT (North Atlan-tIc), OZEANUS AETHIOPICUS (South Atlantic) and MARE MEDI-TERRANEUM. The continents can be seen in large cursive letters: AMERICA SEP (septentrionalis = North America), AMERICA MERIDI (meridionalis = South America), EUROPA, AFRICA and ASIA. There are two dark patches on the lower edge, which show that Australia had not yet been recognized as a continent. In the non-European parts of the earth we can as a continent. In the non-European parts of the earth we can read names of countries, islands, rivers and lakes - proving a considerable geographical knowledge at that time. In Europe we can also see (without names) Scandinavia with the North Sea and the Baltic, England and Ireland, the Iberian peninsula, Italy and the Balkans.

5 - Spandrel with the lion of St Mark

The practice of decorating astrolabes with a map of Germany, Europe or the world had already begun in the 16^th century and was largely a question of fashion. However, this map on our clock does have a practical use as well: we know that it is midday in Münster when the sun is in line with the Münster meridian. With the help of the map of the world we can calculate how many hours earlier or later other parts of the world have their midday. For example, we might want to calculate the time difference between Münster and Singapore. If we draw an imaginary line from the centre of the clock face to its edge through the point on the map where Singapore should be, the line meets the number V on the right-hand side of the clock face.

This means that the sun has to move from V to XII (seven hours) to the Münster meridian: thus, Singapore is seven hours ahead of Münster. If we want to calculate the time difference of a place to the left of the meridian, then this place is behind Münster in time, and the time has to be subtracted from that of Münster to find the local time in that place.

6 - Trumpeter and women, full hour

Whilst the planisphere and the map of the world are fixed as the background of the astrolabe, the rete in front of them and the hands of the clock are turned by a mechanism in accordance with their real movements. Thus, this is called a moving astrolabe, or astrolabium mobile.

The rese (4) is the decorative wheel with the zodiac and several fixed stars which turns to show the apparent motion of the stars. The original rete of 1540 was made of wood and was replaced by a new one in Baroque style with arabesques and floral embellishments in 1670. Because this rete was also of wood, it deteriorated badly throughout the years, and there were several pieces missing when the clock was last renovated in the 1920s. Therefore, in 1930, the rete was replaced yet again - this time cast in bronze, but keeping the Baroque form of the 17^th century.

7 - Chronos and Death, quarter hour

We can no longer tell how many stars were on the old rete of 1670. There are fifteen on the present one, all of which were important for medieval astrology.

This zodiac circle (5) is fixed as an eccentric wheel. Its outer edge is divided into 360 red and white sections which become narrower the nearer they are to the eccentric pivot of the rete. The division into 360 degrees is not calculated from the centre of the wheel itself but from its pivot - in stereographic projection. That is why the areas alloted to the various signs of the zodiac are also of different sizes. This can be seen quite clearly on illustration number 3. We can also see that each sign of the zodiac is represented by its traditional picture, its Latin name, its astronomical symbol, and its "character", that is, whether the sign is regarded as good, evil or neutral. In this way, all she important facts for astrological medicine could be read directly from the clock.

The most conspicuous hand of the clock is the sun or hour hand (6), which stretches across the whole diameter of the clock face. Because this hand shows the apparent path of the sun for the observer, it moves in an anti-clockwise direction.

On one half of the hand we see the sun and on the other half a rainbow - these two symbols thus standing opposite each other here as they do in nature. This disc representing the sun turns so that the sun's face is always upright. In the 19th century and before, this hand showed the true local time, but now it shows the Central European Time. The hours are displayed in Roman numerals from I to XII twice around the clock face, and each section representing one hour on the edge of the clock has an ornamental leaf in its centre. The minutes can be read from the 4 x 15 small coloured lines between the Roman numerals representing the hours. These are named as the "Horarü minutae" (7) on the lower edge of the clock face.

Apart from the apparent daily course of the sun around the earth in 24 hours, the changes in the earth's declination are shown, that is, the change of the seasons. The sun moves a little along its hand each day; in winter it is at the outer edge of the clock face, in summer near the centre. A simple device allows this movement: behind the disc representing the sun is a pin, which engages a serration on the zodiac wheel.

Because the daily course of the sun is four minutes longer than that of the other fixed stars (here, the rete), the position of the sun also has to change in accordance with the zodiac.

8 - Gable with the Holy Mother and Child

This slight change results in a third movement of the sun: in the course of a year the sun moves through all the houses of the zodiac.

The moon hand (8) consists of a thin tube around a rod. The tube is moved by cogwheels in such a way that the true movement of the moon is given: it travels around the axis of the clock about 28.5 times in the same time that the sun travels 29.5 times around the clock. At the end of this outer tube is a concave hemisphere with its open half towards the observer. In this has been placed a small figure of the moon, half black and half silver, which is connected to the inner rod of the hand. In its turn, this rod is connected to the sun hand by means of a cogwheel, turning around its own axis in 29.5 days. In this way we can observe the phases of the moon.

Apart from the hands for the sun and moon there are five further hands representing the planets known in the 16th century: Mercury, Venus, Mars, Jupiter and Saturn. They are of differing lengths; on the end of each is a golden star and the name of the planet. The hand for Mercury is connected directly to that of the sun. The hand does not revolve around the sun, unlike the real planet; a representation of this movement would not have been worth the trouble because the planet is rarely visible in the sky. The hand for Venus takes 584 days for its course around the disc of the sun, and the hands of the other three planets move around the clock at their own speeds: Mars takes 1.9 years to complete its course, Jupiter 11.9 years, and Saturn 29.5 years. The two 2.30 m long boards to the left and right of the clock face are called the table of planets (9). From bottom to top on the right and from top to bottom on the left we can see which planet governs each hour of the day. The planets here are in the order determined by Ptolemy: Saturn, Jupiter, Mars, Sol (= sun), Venus, Mercury, Luna (= moon). The planet at the bottom right not only governs the first hour of the day but also the day itself, giving the day its name, thus:

The names of the planets were painted onto 24 seven-sided boards, each 5 cm thick. Each turns to the next of the seven sides at midnight.

9 - Left gallery

The Münster painter Ludger tom Ring the Elder was responsible for the exquisite artwork on the centre part of the clock. In the spandrels (10) between the border and clock face he painted the representatives of the four Evangelists on a red background. Each has a banderol with a quotation from the relevant Gospel. Below, to left and right, are the mighty oxen and lion, representing Luke and Mark respectively.

Above are the creatures of the air: left, the eagle of John; right, the angel of Matthew.

The Procession of the Three Magi

Visitors are often fascinated by the gable of the clock, the procession of the Three Magi and the group of figures which strike the hours and quarter hours on smali mouldings to the left and right of the clock. On the left stands the watchman or Trumpeter and Woman (11) - both the work of a woodcarver whose name we can no longer trace. This watchman in the costume of a lansquenet sounds the number of hours on his horn. The former pennant attached to his trumpet was replaced by one in the cathedral colours of yellow-red-yellow. The woman at his side, dressed in traditional costume of the 16^th century, answers every blow of the horn by a stroke of the bell. The inscription on the ornamental mouding tells us that this group was renovated in 1687.

10 - Right gallery

On a small moulding to the right of the clock stand Chronos, the God of Time, and Death (12). This group was carved by Johann Mauritz Gröninger and put in place in 1696; up to that time there had been no striking of the quarter hour.

Death holds the arrow of death in his left hand and strikes each quarter hour on the bell. Chronos, or Time, hurries with wings spread and turns the hour-glass at every quarter hour. The wooden hour-glass of the 17^th century was replaced by a glass one in 1955.

The Renaissance gable of the clock is a masterpiece. Here the artist Ludger tom Ring has given us a work of art whose delicate workmanship cannot be fully appreciated because it is so far above our heads. It is here that the artist has left his mark: in the entablature above the Holy Mother's head he placed a small square with a richly ornamented letter 'L'. In the centre of the gable on which the figure of the Madonna stands we can see the vear 1542. A further indication makes it quite clear who the originator of the technical and artistic masterpiece was: above the carillon is LVDGERI RINGII MO(NASTER)IENSIS OPUS, the work of Ludger tom Ring from Münster.

The Holy Mother and Child (13) is slightly raised on a pedestal, thus remaining visible during the procession of the Three Magi. Behind and to each side of the Madonna are five pillars with beautiful capitals. Behind her we can see a room in which Joseph is standing. To the right and left are doors through which the Three Magi process.

In the gable above the Madonna this whole construction is continued in a more delicate form and is crowned by an ornamental niche (14), in which King David stands holding the head of Goliath.

On each side of the centre piece we are given the view of an arcade connecting the centre piece with the galleries (15), whose three-dimensional quality is remarkable. Here again we can see the twin arches, divided from each other by plaster. Spectators are crowding at the balustrades, not wanting to miss any of the procession of the Three Magi Two of the spectators are recognisable. The man on the left, standing nearest to the Madonna and leaning over the balustrade, is Ludger tom Ring himself. The beardless young man to his left, turned slightly towards an older man as if listening, is his son, Hermann tom Ring. It is not possible to identify any of the other spectators; but it remarkable that there are neither priests nor women amongst the sixteen figures on the left or the eighteen figures on the right.

11 - The procession of the Three Magi

When the hour and quarter hour have been struck at 12 noon, the Procession of the Three Magi begins. The door to the right of the Madonna opens, and the three wise men appear, preceded by a young servant: the Moor Caspar (or Jaspar), Melchior, and the wise old Balthasar. Each bears a gift in his left hand; the right hand is raised slightly. At the end of the procession comes an older, bearded servant. The sashes of the two servants bear the initials of their masters: J M B. All the figures are carved out of wood, the three wise men having movable limbs: each king, steps before the Holy Mother and Child, turns towards them to pay homage and bows low before them. This does not apply to the servants, who merely pass by.

The Three Magi wear costly brocades with gold braid and lambskin collars. The procession leaves by the door to the left. During the ceremony the Star of Bethlehem moves over the scene from right to left.

When the door opens to begin the procession, the carillon (16) begins, accompanying the double procession with its clear tones. The carillon has ten bells, and various tunes can be played by the selection of notes. The speed of the melody can be adjusted; the mechanism (which drives the star and the turn-table on which the wise men stand) is connected to the player roll.

The Calendar

In the lower part of the clock, behind a late Gothic trellis, is the calendar. The whole disc is compactly inscribed and can be divided into three sections. From the outer edge to the inner part of the disc we can find the following information:

Zone I

• 1. The years
• 2. The Easter letters
• 3. The Golden Number
• 4. The Sunday letters (two rings)
• 5. The Intervallum (two rings)
• 6. The Indiction

Zone II

• 7. The dates in the modern system
• 8. The letters for the day
• 9. The dates in the Roman system
• 10. The names of the months
• 11. The immovable feasts
• 12. The Easter letters

Zone III

• 13. The calendar verses
• 14. The pictures of the months

The details in the rings of the outer Zone I refer to the 532 years from 1540 to 2071. This zone is divided radially into 532 sections. The calendar begins with the year 1540, the year the clock was built. The calculations were made according to the Julian calendar, which was used at that time; this was replaced by the Gregorian calendar in Münster in 1583.

Therefore, not all the information we can find on the calendar is valid today, but they can easily be converted to our present system. According to the Julian calendar, the information about the sun fails on the same month and weekday every 28 years, the same information about the moon every 19 years. That is how the number of years was calculated: 28 × 19 = 532 years.

Ring I, 1 contains the years, which, like all numbers on the calendar, are given in Roman numerals. A long pointer coming from the centre of the calendar indicates the year.

This pointer must be moved to the next year by hand on New Year's Day.

Ring 1,2 gives the Easter letter, which stands for the date of Easter here (see Ring II, 12) and which the astronomers had calculated for many centuries in advance.

Ring 1, 3 counts the years according to the 19-year lunar cycle, also called the Golden Numbers. The year 1 BC was used as the beginning for the calculation of these lunar cycles; the Golden Numbers are thus from I to XIX. The year 1970, for example, is the year XIV in the 104^th lunar cycle.

Ring I, 4 gives, instead of the solar cycle, the Sunday letters, which is a similar piece of information. If we assign the seven letters Abcdefg to the days of the year (see Ring II, 8), then one of the letters will fall on the first Sunday of the year.

This letter is the Sunday letter for the whole of the year, and every day to which this leter is assigned is a Sunday. For example, we see the Sunday letter 'c' after the year 1543; all days to which the letter 'c' is assigned in the year 1543 were Sundays. In leap years the Sunday letter becomes the next letter in sequence after the additional day (24^th of February).

The leap year 1544, for example, had the Sunday letter f until the 24^th of February, and from then on the letter 'e'.

These retrogressive Sunday letters accompany the 28-year solar cycle in such a way that year 1 of each solar cycle is a leap year, begins on a Monday and has the Sunday letter 'f'; the last year of each solar cycle has the Sunday letter 'A'. The year 9 BC was used as the beginning for the calculation of these lunar cycles. The year 1970, for example, is the year XIX in the 71^st solar cycle. Because of the Gregorian calendar reform, the Sunday letters have been displaced 3, 4, 5 or - in 1900 - 6 days. Thus, if the Sunday letter 'e' is indicated for the year 1970, the days thus indicated are not Sundays, which has the letter 'd' - six days later in the cycle.

12 - The calendar

Ring I, 5 indicates the Intervallum: just as the date of Easter changes every year, so does the period between Christmas and Easter, or rather, between Christmas and Shrove Tuesday. The period of time between Shrove Tuesday and Easter is always constant. Thus, the Intervallum is any period of time related directly or indirectly to Easter; on this calendar it is the period between Christmas and Shrove Tuesday in weeks and days. This period of time varies between 5 weeks 6 days and 10 weeks 5 days.

Ring I, 6 gives another cyclic period of time (from I to XV), namely the Indiction, which was a further aid to the calculation of the date. The Indiction is said to be derived from the ancient Roman taxation law. Medieval mathematicians reckoned the beginning of the cycle from the year 3 BC.

A broad green line separates zone I from zone II. The details in this zone refer to the days of the year, which is why this zone is divided radially into 365 sections. The calendar turns to the next day during the night, and in leap years it must be stopped for one day. The small herald (17) to the left of the calendar points to the day with his staff. On his shield are the words HAEC EST DIES HODIERNA, this is the present day.

There are six pieces of information for each day in zone I.

In Ring II, 7 the days are given in normal fashion.

In Ring I, 8 we see the letters Abcdefg once again - this time repeated in sequence throughout the year, starting at the 1^st of January (see Ring I, 4); they stand for the days of the week. All days represented by the letter 'A' are the same day of the week as the 1^st of January. If the 1^st of January was a Thursday, then all following days with the letter 'A' are also Thursday. In a leap year, when the calendar is halted for one day on the 24^th of February, this day and the following day (25^th of February) have the same letter. Thus the system is not disrupted.

In Ring II, 9 the days are given according to the Roman system: in calends, nones and ides.

In Ring I, 10 we can see the names of the months, written parallel to the circumference of the disc.

Then, in Ring IL, 11 are the immovable feasts and the holy days. Most of the feasts are those celebrated in Münster in the 16^th century, and gaps were filled by holy days celebrated in other dioceses.

The information in Ring I, 12 - the Easter letters - were of particular interest in former times. The date of Easter is still determined by the moon, even today: Easter is the first Sunday after the spring full moon. The spring full moon can occur on the 21^st of March at the earliest and the 18^th of April at the latest - meaning that Easter can fall on the 22^nd of March at the earliest and the 25^th of April at the latest. If one assigns the letters a to v(= u) twice and A to T once in order to the days of the year (beginning at the 1^st of January), then Easter can fall on the days with b c d . . . t v A B . . . Q. This means that the date of Easter can be seen from a knowledge of the Easter letters. For example, if we find the letter 'r' next to the year Mdl = 1550 in Ring I, 2 and then look for the letter 'r' in Ring II, 12, we will find that this letter represents the 6^th of April - thus, in the year 1550 Easter fell on the 6^th of April.

13 - The calendar, section

However, these letters are only valid until 1583, the year of the calendar reform. For all years following 1583 this information is worthless.

The inner zone III is occupied by a tracery, in the middle of which is a figure of Saint Paul, the patron saint of this cathedral. The twelve signs of the zodiac can be found on thin stems coming from the center of the tracery, and the twelve pictures of the months (Ring III, 14) surround the the figure of the saint like a garland. Although the original artwork was spoilt by restorations, these scenes of everyday life of 16^th century Münster are still a joy to the eye.

Contemporary art historians think this to be the work of the Münster artist Ludger tom Ring the Elder, who was also responsible for the paintings on the central and upper parts of the clock.

14 - Picture for the month of July

15 - Picture for the month of November

In Ring III, 13, the innermost ring of the white disc and belonging actually to the pictures of the months, we see a verse for each month. These verses are next to the pictures to which they apply and refer to the activities depicted in the pictures.

In translation the verses are as follows:

January loves wine and drinks with relish at the fireside

February closes all rivers with a blanket of ice

Then, March trims our vines and ploughs the fields

April brings forth the flowers and opens up the earth

Springs and greenery are the tinder of love in May

June brings the frolicing lambs under the shears

July mows the meadows and gives our cattle nourishing hay

And August brings home the harvested grain

September sows the seed in the diligently ploughed furrows

And October joyfully harvests the golden grapes

Everyone's joy is great when November slaughters the fatted pig

December can be seen in the woods, gathering wood for the fireside

Finally, let us take a look behind the decorative facade of the cathedral clock. The mechanism is almost the same as that of any modern church clock; there are, however, one or two special features worth mentioning.

16 - The mechanism of 1930

The works regulate the running of the clock with the striking of the hours and quarter hours, but also the movements of the figures on the outer side of the clock. Furthermore, the works start the motor for the carillon every day at twelve noon. The mechanism for the player roll is also connected to the mechanism driving the star and the turn-table on which the Three Magi stand. Three additional clocks are also connected to the mechanism; one of them operates the ringing of the angelus three times a day. The most complicated special feature of this clock is the mechanism for the planetary gears, which is connected to the main mechanism by a drive shaft with numerous cogwheels.

And what information can we find on the clock?

On the astrolabe:

• The hours (6) and minutes (7)
• The sign of the zodiac in which the sun can be found (5)
• The phase of the moon (8)
• The position of the sun and planets

On the table of planets:

• The day of the week (9)

On the calendar:

• The year (Ring I, 1)
• The month (Ring II. 10)
• The verse of the month (Ring III, 13)
• The picture of the month (Ring III, 14)
• The day (Ring II, 7)
• The holy day and feast day (Ring II, 11)