Editing Ole Rømer (section)

== Biography ==
[[File:Rundetårn over rooftops.JPG|thumb|''[[Rundetårn]]'' ("round tower") in [[Copenhagen]], on top of which the university had its observatory from the mid 17th century until the mid 19th century when it was moved to new premises. The current observatory there was built in the 20th century to serve amateurs.]]
Rømer was born on 25 September 1644 in [[Aarhus]] to merchant and skipper Christen Pedersen (died 1663), and Anna Olufsdatter Storm ({{Circa|1610}} – 1690), daughter of a well-to-do [[alderman]].<ref name="Dalgaard1996">{{cite book
| author    = Niels Dalgaard
| title     = Dage med Madsen, eller, Livet i Århus: om sammenhænge i Svend Åge Madsens forfatterskab
| url       = https://books.google.com/books?id=wunQTxJQAA8C&pg=PA169
| date      = 1996
| publisher = Museum Tusculanum Press
| language  = da
| isbn      = 978-87-7289-409-6
| pages     = 169–
| quote     = ... skipper og handelsmand i Århus, gift med Anne Olufsdatter Storm (død 1690) og far til astronomen Ole Rømer (1644–1710).
}}</ref> Since 1642, Christen Pedersen had taken to using the name Rømer, which means that he was from the Danish island of [[Rømø]], to distinguish himself from a couple of other people named Christen Pedersen.<ref>{{cite book
| last      = Friedrichsen
| first     = Per
| author2   = Tortzen, Chr. Gorm
| title     = Ole Rømer&nbsp;– Korrespondance og afhandlinger samt et udvalg af dokumenter
| date      = 2001
| publisher = C. A. Reitzels Forlag
| location  = Copenhagen
| language  = da
| isbn      = 87-7876-258-8
| pages     = 16
}}</ref> There are few records of Ole Rømer before 1662, when he graduated from the old [[Aarhus Katedralskole]] (the [[Cathedral school]] of Aarhus),<ref>{{cite book
| title     = Bogvennen
| url       = https://books.google.com/books?id=Ply5AAAAIAAJ
| volume    = 1-9
| date      = 1971
| publisher = Fischers forlag
| language  = da
| pages     = 66–
| quote     = Denne antagelse tiltrænger en nærmere redegørelse: Ole Rømer udgik som student fra Aarhus Katedralskole i 1662. Ole Rømer Skolens rektor på den tid var Niels Nielsen Krog, om hvem samtidige kilder oplyser, at "hans studium ...
}}</ref><ref name="LindHenriksen2003">{{cite book
 |author1   = Olaf Lind
 |author2   = Poul Ib Henriksen
 |title     = Arkitektur Fortaellinger/Building of Aarhus University
 |url       = https://books.google.com/books?id=BtxKO1PzadgC&pg=PA21
 |date      = 2003
 |publisher = Aarhus Universitetsforlag
 |language  = da
 |isbn      = 978-87-7288-972-6
 |pages     = 21–
 |quote     = Ole Rømer tog iøvrigt studentereksamen fra Latinskolen i Århus (Katedralskolen) i 1662.
}}{{Dead link|date=February 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> moved to Copenhagen and matriculated at the [[University of Copenhagen]]. His mentor at the University was [[Rasmus Bartholin]], who published his discovery of the [[double refraction]] of a light ray by [[Iceland spar]] (a transparent form of the mineral [[calcite]]) in 1668, while Rømer was living in his home. Rømer was given every opportunity to learn mathematics and astronomy using [[Tycho Brahe]]'s astronomical observations, as Bartholin had been given the task of preparing them for publication.<ref>Friedrichsen; Tortzen (2001), pp. 19–20.</ref>

Rømer was employed by the French government: [[Louis XIV of France|Louis XIV]] made him tutor for the [[Dauphin of France|Dauphin]], and he also took part in the construction of the magnificent [[fountain]]s at [[Palace of Versailles|Versailles]].

In 1681, Rømer returned to Denmark and was appointed professor of [[astronomy]] at the University of Copenhagen, and the same year he married Anne Marie Bartholin, the daughter of [[Rasmus Bartholin]]. He was active also as an observer, both at the University [[Observatory]] at [[Rundetårn]] and in his home, using improved instruments of his own construction. Unfortunately, his observations have not survived: they were lost in the great [[Copenhagen Fire of 1728]]. However, a former assistant (and later an astronomer in his own right), [[Peder Horrebow]], loyally described and wrote about Rømer's observations.

In Rømer's position as royal mathematician, he introduced the first national system for weights and measures in Denmark on 1 May 1683.<ref name="SchultzDahlberg2013">{{cite book
| author1   = Mai-Britt Schultz
| author2   = Rasmus Dahlberg
| title     = Det vidste du ikke om Danmark
| url       = https://books.google.com/books?id=paqvAQAAQBAJ&pg=PT53
| date      = 31 October 2013
| publisher = Gyldendal
| language  = da
| isbn      = 978-87-02-14713-1
| pages     = 53–
| quote     = I 1683 udarbejdede Ole Rømer en forordning, der fastsatte den danske mil samt en række andre mål, hvilket var hårdt tiltrængt, for indtil da havde der hersket et sandt enhedskaos i Danmark/Norge. Eksempelvis var en sjællandsk alen 63 centimeter, ...
}}</ref><ref name="ChristiansenRiis1982">{{cite book
| author1   = Poul Aagaard Christiansen
| author2   = Povl Riis
| author3   = Eskil Hohwy
| title     = Festskrift udgivet i anledning af Universitetsbibliotekets 500 års jubilæum 28. juni 1982
| url       = https://books.google.com/books?id=teoYAAAAIAAJ
| date      = 1982
| publisher = Lægeforeningen
| language  = da
| pages     = 87–
| quote     = En studie i Ole Rømers efterladte optegnelser, Adversaria, som hans enke Else Magdalene ... at give Christian V's kongelige mathematicus Ole Rømer (1644–1710) æren for udformningen af forordningen af 1.V.1683 ...
}}</ref> Initially based on the Rhine foot, a more accurate national standard was adopted in 1698.<ref name="Thomas2010">{{cite book
| author    = Alastair H. Thomas
| title     = The A to Z of Denmark
| url       = https://books.google.com/books?id=MKH4JuPT6boC&pg=PA422
| date      = 10 May 2010
| publisher = Scarecrow Press
| isbn      = 978-0-8108-7205-9
| pages     = 422–
| quote     = ... although uniformity throughout the country was not achieved until statutes of 1683 and 1698, under the leadership of Ole Romer. The metric system was adopted in 1907 and is universal, though colloquially units such as tomme, tønde land, ...
}}</ref> Later measurements of the standards fabricated for length and volume show an excellent degree of accuracy. His goal was to achieve a definition based on astronomical constants, using a [[pendulum]]. This would happen after his death as practicalities made it too inaccurate at the time. Notable is also his definition of the new [[Danish units of measurement|Danish mile]] of 24,000 Danish feet (circa 7,532&nbsp;m).<ref name="Nørlund1944">{{cite book
| author    = Niels Erik Nørlund
| title     = De gamle danske længdeenheder
| url       = https://books.google.com/books?id=DGvnAAAAMAAJ
| date      = 1944
| publisher = E. Munksgaard
| language  = da
| pages     = 74–
| quote     = ... Maj 1683 gennemførte Reform af Maal og Vægt fastsatte Ole Rømer den danske Mils Længde til 12 000 danske Alen.
}}</ref>

In 1700, Rømer persuaded the king to introduce the [[Gregorian calendar]] in [[Denmark-Norway|Denmark and Norway]]&nbsp;– something [[Tycho Brahe]] had argued for in vain a hundred years earlier.<ref name="Tjørnhøj-Thomsen2011">{{cite book
| author    = K. Hastrup
| author2   = C. Rubow
| author3   = T. Tjørnhøj-Thomsen
| title     = Kulturanalyse&nbsp;– kort fortalt
| url       = https://books.google.com/books?id=HIA_ZrqlPSkC&pg=PA219
| date      = 2011
| publisher = Samfundslitteratur
| language  = da
| isbn      = 978-87-593-1496-8
| pages     = 219–
| quote     = I Danmark blev den gregorianske kalender indført den 1. marts 1700 efter forarbejde af Ole Rømer. Man stoppede med brug af den julianske kalender den 18. februar, og sprang simpelthen de næste 11 dage over, så man landede direkte på  ...
}}</ref>

[[File:Ole Rømer at work.jpg|thumb|left|200px|Ole Rømer at work]]
Rømer developed a [[temperature]] scale while convalescing from a broken leg.<ref name="Shachtman2000">{{cite book
| author    = Tom Shachtman
| title     = Absolute Zero and the Conquest of Cold
| url       = https://books.google.com/books?id=IJ91od-UYygC
| date      = 12 December 2000
| publisher = Houghton Mifflin Harcourt
| isbn      = 0-547-52595-8
| pages     = 48–
| quote     = ... down to an almost mythical point, an absolute zero, the end of the end. Around 1702, while Amontons was doing his best work in Paris, in Copenhagen the astronomer Ole Romer, who had calculated the finite speed of light, broke his leg. Confined to his home for some time, he took the opportunity of forced idleness to produce a thermometer having two fixed points ...
}}</ref> After visiting with Rømer in 1708, [[Daniel Gabriel Fahrenheit]] began making his thermometers using a modified version of [[Rømer scale|Rømer's scale]] that eventually evolved into the [[Fahrenheit scale]] still popular in the United States and a few other countries.<ref name="Rittner2009">{{cite book
| author    = Don Rittner
| title     = A to Z of Scientists in Weather and Climate
| url       = https://books.google.com/books?id=nU_jIyhvKOUC&pg=PA54
| date      = 1 January 2009
| publisher = Infobase Publishing
| isbn      = 978-1-4381-0924-4
| pages     = 54–
| quote     = Fahrenheit's first thermometers, from about 1709 to 1715, contained a column of alcohol that directly expanded and contracted, based on a design made by Danish astronomer Ole Romer in 1708, which Fahrenheit personally reviewed. Romer ...
}}</ref><ref>{{cite book
| title     = Popularization and People (1911–1962)
| url       = https://books.google.com/books?id=dpb1GaDPoq0C&pg=PA431
| date      = 22 October 2013
| publisher = Elsevier
| isbn      = 978-0-08-046687-3
| pages     = 431–
| quote     = ... letter from Fahrenheit to his Dutch colleague Hermann Boerhaave (1668–1738) dated 17 April 1729 in which Fahrenheit describes his experience at Rømer's laboratory in 1708.
}}</ref><ref name="SchlagerLauer2001">{{cite book
| author1   = Neil Schlager
| author2   = Josh Lauer
| title     = Science and Its Times: 1700–1799
| url       = https://books.google.com/books?id=6I1FAAAAYAAJ
| date      = 2001
| publisher = Gale Group
| isbn      = 978-0-7876-3936-5
| pages     = 341–
| quote     = In 1708 Fahrenheit visited Ole Romer (1644–1710). Since at least 1702 Romer had been making alcohol thermometers with two fixed points and a scale divided into equal increments. He impressed upon Fahrenheit the scientific importance of ...
}}</ref>

Rømer also established navigation schools in several Danish cities.<ref name="PetersenAndersen1929-715">{{cite book
| author1   = Carl Sophus Petersen
| author2   = Vilhelm Andersen
| author3   = Richard Jakob Paulli
| title     = Illustreret dansk litteraturhistorie: bd. Den danske littterature fra folkevandringstiden indtil Holberg, af C.S. Petersen under medvirkning af R. Paulli
| url       = https://books.google.com/books?id=9MUSAAAAMAAJ
| date      = 1929
| publisher = Gyldendai
| language  = da
| pages     = 716–
| quote     = ... Det var paa hans Tilskyndelse, at de første Navigationsskoler (i København og Stege) oprettedes, og Bestyrerpladserne besatte han med de bedste ...
}}</ref>

In 1705, Rømer was made the second Chief of the Copenhagen [[Police]], a position he kept until his death in 1710.<ref name="SarlemijnSparnaay2013">{{cite book
| author1   = A. Sarlemijn
| author2   = M.J. Sparnaay
| title     = Physics in the Making: Essays on Developments in 20th Century Physics
| url       = https://books.google.com/books?id=B_FGBQAAQBAJ&pg=PA48
| date      = 22 October 2013
| publisher = Elsevier Science
| isbn      = 978-1-4832-9385-1
| pages     = 48–
| quote     = The other, Ole Rømer, was Bartholin's amanuensis, later his son-in-law. ... man, became the Danish king's mathematician (mathematicus regius), professor of astronomy at the University of Copenhagen, and eventually chief of police of that city.
}}</ref> As one of his first acts, he fired the entire force, being convinced that the morale was alarmingly low. He was the inventor of the first street lights (oil lamps) in Copenhagen, and worked hard to try to control the beggars, poor people, unemployed, and prostitutes of Copenhagen.<ref name="informationsafdelingen1970">{{cite book
| author    = Denmark. Udenrigsministeriet. Presse- og informationsafdelingen
| title     = Denmark. An official handbook
| url       = https://books.google.com/books?id=FuoiAQAAIAAJ
| date      = 1970
| publisher = Krak
| isbn      = 978-87-7225-011-3
| pages     = 403–
| quote     = It was perhaps fortunate that Ole Romer (1644–1710) was called home to Denmark after he had achieved world fame by ... of Copenhagen and oblige him to devote time and energy to thinking out measures against prostitution and begging.
}}</ref><ref name="OlsenAskgaard1985">{{cite book
| author1   = Gunnar Olsen
| author2   = Finn Askgaard
| title     = Den unge enevaelde: 1660–1721
| url       = https://books.google.com/books?id=XAsWAQAAMAAJ
| date      = 1985
| publisher = Politikens Forlag
| language  = da
| isbn      = 978-87-567-3866-8
| pages     = 368–
| quote     = Det var et held, at Ole Rømer først blev kaldt tilbage til den danske hovedstad, efter at han i Paris havde opnået ... Men at denne geniale forsker som Københavns politimester skulle beskæftige sig med forholdsregler mod prostitution og betleri, ..
}}</ref>

In Copenhagen, Rømer made rules for building new houses, got the city's water supply and sewers back in order, ensured that the city's fire department got new and better equipment, and was the moving force behind the planning and making of new pavement in the streets and on the city squares.<ref name="Samfund1914">{{cite book
| author    = Danmarks Naturvidenskabelige Samfund
| title     = Ingeniørvidenskabelige skrifter
| url       = https://books.google.com/books?id=vldVAAAAMAAJ
| date      = 1914
| publisher = Danmarks naturvidenskabelige samfund, i kommission hos G.E.C. Gad
| language  = da
| pages     = 108–
| quote     = I de følgende Aar udstedtes der en Række Forordninger om Gaderne; de skyldes uden Tvivl Ole Rømer. Snart er det Brolægningen, det gælder, snart et omhyggeligt Reglement for Færdslen i Gaderne. Brolægningen havde medført store ...
}}</ref><ref name="Bech1967">{{cite book
| author    = Svend Cedergreen Bech
| title     = Københavns historie gennem 800 år
| url       = https://books.google.com/books?id=8F4QAQAAIAAJ
| date      = 1967
| publisher = Haase
| language  = da
| pages     = 246–
| quote     = 1705-10 beklædtes politimesterembedet af fysikeren Ole Rømer, i hvis embedstid mange reformer forsøgtes. Brolægning og belysning forbedredes, vandforsyning og vandafledning blev taget op til revision, men heller ikke en så ...
}}</ref><ref name="Kjerulf1964">{{cite book
| author    = Axel Kjerulf
| title     = Latinerkvarteret; blade af en gemmel bydels historie
| url       = https://books.google.com/books?id=xTDTAAAAMAAJ
| date      = 1964
| publisher = Hassings forlag
| language  = da
| pages     = 44–
| quote     = Ole Rømer vendte i 1681 tilbage til København, hvor han blev professor i astronomi ved universitetet og giftede sig med Rasmus ... justering af mål og vægt, blev ham betroet foruden ordning af byggeforhold, gaders brolægning og belysning.
}}</ref>

Rømer died at the age of 65 in 1710. He was buried in [[Church of Our Lady (Copenhagen)|Copenhagen Cathedral]], which has since been rebuilt following its destruction in the [[Battle of Copenhagen (1807)]]. There is a modern memorial.<ref name="TrimbleWilliams2007">{{cite book
| author1   = Virginia Trimble
| author2   = Thomas R. Williams
| author3   = Katherine Bracher
| author4   = Richard Jarrell
| author5   = Jordan D. Marché
| author6   = F. Jamil Ragep
| title     = Biographical Encyclopedia of Astronomers
| url       = https://books.google.com/books?id=t-BF1CHkc50C&pg=PA983
| date      = 18 September 2007
| publisher = Springer Science & Business Media
| isbn      = 978-0-387-30400-7
| pages     = 983–
}}</ref>