Zimmer Tower
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The Zimmer tower ( nl, Zimmertoren) is a tower in
Lier, Belgium Lier (; french: Lierre, ) is a municipality located in the Belgium, Belgian province of Antwerp (province), Antwerp. It is composed of the city of Lier proper and the village of Koningshooikt. The city centre is surrounded by the river ''Nete'', a ...
, also known as the Cornelius tower, that was originally a
keep A keep (from the Middle English ''kype'') is a type of fortified tower built within castles during the Middle Ages by European nobility. Scholars have debated the scope of the word ''keep'', but usually consider it to refer to large towers in c ...
of Lier's 14th-century city fortifications. In 1930, astronomer and
clockmaker A clockmaker is an artisan who makes and/or repairs clocks. Since almost all clocks are now factory-made, most modern clockmakers only repair clocks. Modern clockmakers may be employed by jewellers, antique shops, and places devoted strictly t ...
Louis Zimmer Louis Zimmer (8 September 1888 – 12 December 1970) was an astronomer and clockmaker to the King of Belgium. Most notably in 1930 he built the Jubilee (or Centenary) Clock, which is displayed on the front of the Zimmer tower. The Zimmer tower ( ...
(1888–1970) built the Jubilee (or Centenary) Clock, which is displayed on the front of the tower, and consists of 12 clocks encircling a central one with 57 dials. These clocks showed time on all continents, phases of the moons, times of tides and many other periodic phenomena. In 1980 the tower became a state-protected monument.


Tower building

The original tower was built no later than 1425, though the precise date of construction is unknown. In 1812 the tower was sold by the municipal authorities, but after
World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
, they repurchased it and slated it for demolition. In 1930 astronomer and clockmaker Louis Zimmer donated a complex clock which was installed in the old tower, which had to be substantially reconstructed for this. In honor of the astronomer the structure was renamed the Zimmer tower. In 1960 a pavilion for the new clock was built next to the tower to present Zimmer's masterpiece the wonder-clock. ( nl, Wonderklok). These wonder-clocks were prepared for the 1935 world exhibition in
Brussels Brussels (french: Bruxelles or ; nl, Brussel ), officially the Brussels-Capital Region (All text and all but one graphic show the English name as Brussels-Capital Region.) (french: link=no, Région de Bruxelles-Capitale; nl, link=no, Bruss ...
; later they were demonstrated in the US. Around one of these dials moves the slowest pointer in the world – its complete revolution will take 25800 years, which corresponds to the period of the
precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In othe ...
of the Earth's axis. Subsequently, Zimmer attached to the clocks a mechanical
planetarium A planetarium ( planetariums or ''planetaria'') is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation. A dominant feature of most planetarium ...
. The wonder-clocks impressed
Albert Einstein Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theory ...
, who congratulated Zimmer on the creation of these unusual mechanisms. On the small square at the foot of the tower an exhibition of the
Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
was arranged with the aid of metallic circles and the rings (circles designate the Sun and planets, rings the orbits of planets). These also show
asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...
s ''Felix'' (№ 1664) and ''Zimmer'' (№ 3064), which were named after Felix Timmermans and Louis Zimmer when discovered in 1929, and 1984. In 1980 the tower obtained the status of state protected monument. Now the Zimmer tower and pavilion with the wonder-clocks is a museum.


Description of the dials

The Centenary clock has one large dial in the centre, measuring in diameter. This dial shows the exact time (
UTC+1 UTC+01:00 is an identifier for a time offset from UTC of +01:00. In ISO 8601, the associated time would be written as 2019-02-07T23:28:34+01:00. This time is used in: *Central European Time *West Africa Time *Western European Summer Time ** B ...
; during
daylight saving time Daylight saving time (DST), also referred to as daylight savings time or simply daylight time (United States, Canada, and Australia), and summer time (United Kingdom, European Union, and others), is the practice of advancing clocks (typicall ...
UTC+2 UTC+02:00 is an identifier for a time offset from UTC of +02:00. In ISO 8601, the associated time would be written as 2020-11-08T23:41:45+02:00. This time is used in: As standard time (year-round) ''Principal cities: Cairo, Pretoria, Cape ...
is used instead). The twelve dials around the centre dial show the following (starting from the dial in the 2 o'clock position and going clockwise): the
equation of time In mathematics, an equation is a formula that expresses the equality of two expressions, by connecting them with the equals sign . The word ''equation'' and its cognates in other languages may have subtly different meanings; for example, in ...
, the
zodiac The zodiac is a belt-shaped region of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the Sun path, apparent path of the Sun across the celestial sphere over the course of the year. ...
, the
solar cycle The solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surfa ...
and the
dominical letter Dominical letters or Sunday letters are a method used to determine the day of the week for particular dates. When using this method, each year is assigned a letter (or pair of letters for leap years) depending on which day of the week the year star ...
, the week, the
globe A globe is a spherical model of Earth, of some other celestial body, or of the celestial sphere. Globes serve purposes similar to maps, but unlike maps, they do not distort the surface that they portray except to scale it down. A model globe ...
, the months, the calendar dates, the seasons, the
tides Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables can ...
, the age of the
moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
, the phases of the moon and the
metonic cycle The Metonic cycle or enneadecaeteris (from grc, ἐννεακαιδεκαετηρίς, from ἐννεακαίδεκα, "nineteen") is a period of almost exactly 19 years after which the lunar phases recur at the same time of the year. The recu ...
and the
epact The epact ( la, epactae, from grc, ἐπακται ἡμεραι () = added days), used to be described by medieval computists as the age of a phase of the Moon in days on 22 March; in the newer Gregorian calendar, however, the epact is reckoned ...
.


The equation of time

This dial shows the difference in minutes between the
apparent solar time Solar time is a calculation of the passage of time based on the position of the Sun in the sky. The fundamental unit of solar time is the day, based on the synodic rotation period. Two types of solar time are apparent solar time (sundial ti ...
and the
mean solar time Solar time is a calculation of the passage of time based on the position of the Sun in the sky. The fundamental unit of solar time is the day, based on the synodic rotation period. Two types of solar time are apparent solar time (sundial ti ...
. Positive values indicate that the apparent solar time is ahead (fast) of the mean solar time, with maxima around 3 November and 15 May. Negative values indicate that the apparent solar time is behind (slow) of the mean solar time, with a maximum lag around 12 February and 27 July. The difference is zero four times a year; around 16 April 15 June, 1 September and 25 December.


The zodiac

Every year the sun describes an imaginary circle around the earth, called the zodiac. The zodiac is divided in twelve segments, each denoted by a sign associated with a constellation. This dial shows the zodiac signs. The signs of spring;
Ram Ram, ram, or RAM may refer to: Animals * A male sheep * Ram cichlid, a freshwater tropical fish People * Ram (given name) * Ram (surname) * Ram (director) (Ramsubramaniam), an Indian Tamil film director * RAM (musician) (born 1974), Dutch * ...
,
Bull A bull is an intact (i.e., not castrated) adult male of the species ''Bos taurus'' (cattle). More muscular and aggressive than the females of the same species (i.e., cows), bulls have long been an important symbol in many religions, includin ...
and
Twins Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two em ...
. The signs of the summer;
Crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...
,
Lion The lion (''Panthera leo'') is a large Felidae, cat of the genus ''Panthera'' native to Africa and India. It has a muscular, broad-chested body; short, rounded head; round ears; and a hairy tuft at the end of its tail. It is sexually dimorphi ...
and
Virgin Virginity is the state of a person who has never engaged in sexual intercourse. The term ''virgin'' originally only referred to sexually inexperienced women, but has evolved to encompass a range of definitions, as found in traditional, modern ...
. The signs of the fall;
Balance Balance or balancing may refer to: Common meanings * Balance (ability) in biomechanics * Balance (accounting) * Balance or weighing scale * Balance as in equality or equilibrium Arts and entertainment Film * ''Balance'' (1983 film), a Bulgaria ...
,
Scorpion Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic forward curve over the back and always end ...
and Bowman. The signs of winter; Capricorn, Water-bearer and
Fishes Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
. One revolution of this dial takes a year.


The solar cycle and the dominical letter

The solar cycle is a 28-year cycle. After the 28 years, dates reappear in the same order. On the inner circle, the hand indicates the current year of the solar cycle. On the outer circle, the hand shows the corresponding dominical letter. The dominical letter gives the day upon which the first Sunday of the year falls. The letter A means that the first Sunday of the year will fall on 1 January. The letter E for example, indicates that the first Sunday will be on 5 January. Leap years have two dominical letters because the dominical letter changes end February. The first letter covers January and February, the second covers March to December. For leap years, the outer circle will show two dominical letters. The cycle of the dominical letters for common years is twice every 11 years and once every 6 years, while for leap years is once every 28 years. 2008 (
leap year starting on Tuesday A leap year starting on Tuesday is any year with 366 days (i.e. it includes 29 February) that begins on Tuesday, 1 January, and ends on Wednesday, 31 December. Its dominical letters hence are FE. The most recent year of such kind was 2008 and the n ...
) is the year 1 of the cycle, while 2007 (
common year starting on Monday A common year starting on Monday is any non-leap year (i.e., a year with 365 days) that begins on Monday, 1 January, and ends on Monday, 31 December. Its dominical letter hence is G. The most recent year of such kind was 2018 and the next one wi ...
) is the year 28 of the cycle. From 1980 to 2007, respectively, there were: * 1980 was a
leap year starting on Tuesday A leap year starting on Tuesday is any year with 366 days (i.e. it includes 29 February) that begins on Tuesday, 1 January, and ends on Wednesday, 31 December. Its dominical letters hence are FE. The most recent year of such kind was 2008 and the n ...
, those dominical letters hence were FE, was the year 1 of the cycle. * 1981 was a
common year starting on Thursday A common year starting on Thursday is any non-leap year (i.e. a year with 365 days) that begins on Thursday, 1 January, and ends on Thursday, 31 December. Its dominical letter hence is D. The most recent year of such kind was 2015 and the next one ...
, that dominical letter hence was D, was the year 2 of the cycle. * 1982 was a
common year starting on Friday A common year starting on Friday is any non-leap year (i.e. a year with 365 days) that begins on Friday, 1 January, and ends on Friday, 31 December. Its dominical letter hence is C. The most recent year of such kind was 2021 and the next one will ...
, that dominical letter hence was C, was the year 3 of the cycle. * 1983 was a
common year starting on Saturday A common year starting on Saturday is any non-leap year (i.e. a year with 365 days) that begins on Saturday, 1 January, and ends on Saturday, 31 December. Its dominical letter hence is B. The current year, 2022, is a common year starting on Saturd ...
, that dominical letter hence was B, was the year 4 of the cycle. * 1984 was a
leap year starting on Sunday A leap year starting on Sunday is any year with 366 days (i.e. it includes 29 February) that begins on Sunday, 1 January, and ends on Monday, 31 December. Its dominical letters hence are AG. The most recent year of such kind was 2012 and the next o ...
, those dominical letters hence were AG, was the year 5 of the cycle. * 1985 was a
common year starting on Tuesday A common year starting on Tuesday is any non-leap year (i.e. a year with 365 days) that begins on Tuesday, 1 January, and ends on Tuesday, 31 December. Its dominical letter hence is F. The most recent year of such kind was 2019 and the next one wi ...
, that dominical letter hence was F, was the year 6 of the cycle. * 1986 was a
common year starting on Wednesday A common year starting on Wednesday is any non-leap year (a year with 365 days) that begins on Wednesday, 1 January, and ends on Wednesday, 31 December. Its dominical letter hence is E. The most recent year of such kind was 2014, and the next one ...
, that dominical letter hence was E, was the year 7 of the cycle. * 1987 was a
common year starting on Thursday A common year starting on Thursday is any non-leap year (i.e. a year with 365 days) that begins on Thursday, 1 January, and ends on Thursday, 31 December. Its dominical letter hence is D. The most recent year of such kind was 2015 and the next one ...
, that dominical letter hence was D, was the year 8 of the cycle. * 1988 was a
leap year starting on Friday A leap year starting on Friday is any year with 366 days (i.e. it includes 29 February) that begins on Friday 1 January and ends on Saturday 31 December. Its dominical letters hence are CB. The most recent year of such kind was 2016 and the next one ...
, those dominical letters hence were CB, was the year 9 of the cycle. * 1989 was a
common year starting on Sunday A common year starting on Sunday is any non-leap year (i.e. a year with 365 days) that begins on Sunday, January 1, 1 January, and ends on Sunday, December 31, 31 December. Its dominical letter hence is A. The most recent year was 2017 and the next ...
, that dominical letter hence was A, was the year 10 of the cycle. * 1990 was a
common year starting on Monday A common year starting on Monday is any non-leap year (i.e., a year with 365 days) that begins on Monday, 1 January, and ends on Monday, 31 December. Its dominical letter hence is G. The most recent year of such kind was 2018 and the next one wi ...
, that dominical letter hence was G, was the year 11 of the cycle. * 1991 was a
common year starting on Tuesday A common year starting on Tuesday is any non-leap year (i.e. a year with 365 days) that begins on Tuesday, 1 January, and ends on Tuesday, 31 December. Its dominical letter hence is F. The most recent year of such kind was 2019 and the next one wi ...
, that dominical letter hence was F, was the year 12 of the cycle. * 1992 was a
leap year starting on Wednesday A leap year starting on Wednesday is any year with 366 days (i.e. it includes 29 February) that begins on Wednesday 1 January and ends on Thursday 31 December. Its dominical letters hence are ED. The most recent year of such kind was 2020 and the ne ...
, those dominical letters hence were ED, was the year 13 of the cycle. * 1993 was a
common year starting on Friday A common year starting on Friday is any non-leap year (i.e. a year with 365 days) that begins on Friday, 1 January, and ends on Friday, 31 December. Its dominical letter hence is C. The most recent year of such kind was 2021 and the next one will ...
, that dominical letter hence was C, was the year 14 of the cycle. * 1994 was a
common year starting on Saturday A common year starting on Saturday is any non-leap year (i.e. a year with 365 days) that begins on Saturday, 1 January, and ends on Saturday, 31 December. Its dominical letter hence is B. The current year, 2022, is a common year starting on Saturd ...
, that dominical letter hence was B, was the year 15 of the cycle. * 1995 was a
common year starting on Sunday A common year starting on Sunday is any non-leap year (i.e. a year with 365 days) that begins on Sunday, January 1, 1 January, and ends on Sunday, December 31, 31 December. Its dominical letter hence is A. The most recent year was 2017 and the next ...
, that dominical letter hence was A, was the year 16 of the cycle. * 1996 was a
leap year starting on Monday A leap year starting on Monday is any year with 366 days (i.e. it includes 29 February) that begins on Monday, 1 January, and ends on Tuesday, 31 December. Its dominical letters hence are GF. The most recent year of such kind was 1996 and the next ...
, those dominical letters hence were GF, was the year 17 of the cycle. * 1997 was a
common year starting on Wednesday A common year starting on Wednesday is any non-leap year (a year with 365 days) that begins on Wednesday, 1 January, and ends on Wednesday, 31 December. Its dominical letter hence is E. The most recent year of such kind was 2014, and the next one ...
, that dominical letter hence was E, was the year 18 of the cycle. * 1998 was a
common year starting on Thursday A common year starting on Thursday is any non-leap year (i.e. a year with 365 days) that begins on Thursday, 1 January, and ends on Thursday, 31 December. Its dominical letter hence is D. The most recent year of such kind was 2015 and the next one ...
, that dominical letter hence was D, was the year 19 of the cycle. * 1999 was a
common year starting on Friday A common year starting on Friday is any non-leap year (i.e. a year with 365 days) that begins on Friday, 1 January, and ends on Friday, 31 December. Its dominical letter hence is C. The most recent year of such kind was 2021 and the next one will ...
, that dominical letter hence was C, was the year 20 of the cycle. * 2000 was a
leap year starting on Saturday A leap year starting on Saturday is any year with 366 days (i.e. it includes 29 February) that begins on Saturday, 1 January, and ends on Sunday, 31 December. Its dominical letters hence are BA. The most recent year of such kind was 2000 and the n ...
, those dominical letters hence were BA, was the year 21 of the cycle. * 2001 was a
common year starting on Monday A common year starting on Monday is any non-leap year (i.e., a year with 365 days) that begins on Monday, 1 January, and ends on Monday, 31 December. Its dominical letter hence is G. The most recent year of such kind was 2018 and the next one wi ...
, that dominical letter hence was G, was the year 22 of the cycle. * 2002 was a
common year starting on Tuesday A common year starting on Tuesday is any non-leap year (i.e. a year with 365 days) that begins on Tuesday, 1 January, and ends on Tuesday, 31 December. Its dominical letter hence is F. The most recent year of such kind was 2019 and the next one wi ...
, that dominical letter hence was F, was the year 23 of the cycle. * 2003 was a
common year starting on Wednesday A common year starting on Wednesday is any non-leap year (a year with 365 days) that begins on Wednesday, 1 January, and ends on Wednesday, 31 December. Its dominical letter hence is E. The most recent year of such kind was 2014, and the next one ...
, that dominical letter hence was E, was the year 24 of the cycle. * 2004 was a
leap year starting on Thursday A leap year starting on Thursday is any year with 366 days (i.e. it includes 29 February) that begins on Thursday 1 January, and ends on Friday 31 December. Its dominical letters hence are DC. The most recent year of such kind was 2004 and the next ...
, those dominical letters hence were DC, was the year 25 of the cycle. * 2005 was a
common year starting on Saturday A common year starting on Saturday is any non-leap year (i.e. a year with 365 days) that begins on Saturday, 1 January, and ends on Saturday, 31 December. Its dominical letter hence is B. The current year, 2022, is a common year starting on Saturd ...
, that dominical letter hence was B, was the year 26 of the cycle. * 2006 was a
common year starting on Sunday A common year starting on Sunday is any non-leap year (i.e. a year with 365 days) that begins on Sunday, January 1, 1 January, and ends on Sunday, December 31, 31 December. Its dominical letter hence is A. The most recent year was 2017 and the next ...
, that dominical letter hence was A, was the year 27 of the cycle. * 2007 was a
common year starting on Monday A common year starting on Monday is any non-leap year (i.e., a year with 365 days) that begins on Monday, 1 January, and ends on Monday, 31 December. Its dominical letter hence is G. The most recent year of such kind was 2018 and the next one wi ...
, that dominical letter hence was G, was the year 28 and final year of the cycle.


The week

This dial marks the seven days of the week, represented by ancient gods and their symbol.


The globe

The
rotation of the Earth Earth's rotation or Earth's spin is the rotation of planet Earth around its own axis, as well as changes in the orientation of the rotation axis in space. Earth rotates eastward, in prograde motion. As viewed from the northern polar star Pola ...
causes day and night. It is day on the part of the globe that is currently visible. The places on earth that pass under the fixed
meridian Meridian or a meridian line (from Latin ''meridies'' via Old French ''meridiane'', meaning “midday”) may refer to Science * Meridian (astronomy), imaginary circle in a plane perpendicular to the planes of the celestial equator and horizon * ...
(the golden belt running from the North Pole to the South Pole) have noon at the same time. The globe rotates once every 24 hours.


The months

This dial depicts the twelve months. The hand shows the current month. One revolution takes a year.


The calendar dates

This dial shows the exact date. The numbering goes to 31, the maximum number of days in a month. In months that have fewer days (28, 29 or 30), the hand automatically moves forward to the first day of the following month. The months with 31 days are January, March, May, July, August, October and December, the months with 30 days are April, June, September and November. February is the only month with less than 30 days. February has only 28 days (29 days in leap years).


The seasons

The dial shows four drawings by Felix Timmermans, representing the four seasons. Spring is represented by a child with flowers (upper left). The duration of the season is indicated with
Arabic numerals Arabic numerals are the ten numerical digits: , , , , , , , , and . They are the most commonly used symbols to write Decimal, decimal numbers. They are also used for writing numbers in other systems such as octal, and for writing identifiers ...
for the days and
Roman numerals Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, eac ...
for the hours. Spring lasts for 92 days and 11 hours. The summer is represented by a mower and lasts 93 days and 8 hours. Autumn is symbolised by a cornucopia and lasts 89 days and 10 hours. Winter is represented by an old lady reading by the fireside. The duration of the winter is exactly 90 days. On the dividing lines between the drawings is a small globe indicating the part of the globe that is being lit by the Sun at the start of the season. The differences in illumination during the year are caused by the Earth's axial tilt. The hand completes one revolution a year and shows the current season.


The tides

The dial indicates the tides at Lier, Belgium. The biggest ship and the flag without the streamer indicate high water. When the streamer is above the flag it is flood. It is ebb when the streamer is below the flag. At Lier, the water is rising for 3 hours and 53 minutes and falling in the other hours. This dial completes almost two revolutions a day.


The age of the moon

The time between two full moons is about 29 days, 12 hours, 44 minutes. This is the time it takes the Moon to make one orbit around the Earth. The dial shows how many days passed since last new moon, indicating the day in the cycle of the moon and showing on the inner circumference the phases of New Moon ( nl, Nieuwe Maan, N.M.), First Quarter ( nl, Eerste Kwartier, E.K.), Full Moon ( nl, Volle Maan, V.M.) and Last Quarter ( nl, Laatste Kwartier, L.K.).


The phases of the moon

This globe, colored half-gold and half-blue with golden stars, shows the
phases of the moon Concerning the lunar month of ~29.53 days as viewed from Earth, the lunar phase or Moon phase is the shape of the Moon's directly sunlit portion, which can be expressed quantitatively using areas or angles, or described qualitatively using the t ...
. The golden part represents the visible part of the Moon.


The metonic cycle and the epact

The hand on this dial revolves once in 19 years. After this period, the different phases of the moon will fall again on the same dates in the year. The Greek astronomer
Meton Meton of Athens ( el, Μέτων ὁ Ἀθηναῖος; ''gen''.: Μέτωνος) was a Ancient Greece, Greek mathematician, astronomer, list of geometers, geometer, and engineer who lived in Athens in the 5th century BC. He is best known for ...
proved this in 432 BC. On the outer ring, the hand points to the golden number, or the number of the current year in the
metonic cycle The Metonic cycle or enneadecaeteris (from grc, ἐννεακαιδεκαετηρίς, from ἐννεακαίδεκα, "nineteen") is a period of almost exactly 19 years after which the lunar phases recur at the same time of the year. The recu ...
. The inner ring shows the
epact The epact ( la, epactae, from grc, ἐπακται ἡμεραι () = added days), used to be described by medieval computists as the age of a phase of the Moon in days on 22 March; in the newer Gregorian calendar, however, the epact is reckoned ...
, which is the age of the moon on the first of January of the current year.


References

Ceulemans, Luk (1980). Louis Zimmer. vzw Gilde "Heren van Lier" Zimmertorencomité (1982). Stad Lier, zimmertoren en wonderklok


External links


Official Website Zimmertower




at Famous Belgians {{Astronomical clocks Clock towers Towers in Belgium Astronomical clocks Clocks in Belgium Lier, Belgium