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Arago's meridian

Arago medaillon Paris has no shortage of monuments and statues. The largest monument is the size of the inner city of Paris itself and extends from the north side of the périferique to the south side. Yet it is a monument that you can walk past, or right over it if you don't know what to look out for. The monument to Arago is the Paris meridian. The monument consists of copper plates of about 5 centimeters that are attached to the sidewalk where the meridian crosses the streets.

You can follow the whole monument from the north side of the périferique to the south side (or vice versa of course). The walk goes (from the north) through Montmartre over narrow streets, via the 9th arrondisement via the Louvre to the Seine, over the footbridge over the Seine and then through Saint Germain du Pres via the Jardin du Luxembourg to the Paris Observatory, just South of the observatory is the empty plinth where the statue of Arago once stood. The walk south to the périferique is less interesting.

arago05.jpg And everywhere you are looking for the medallions on the ground with the name Arago. The medallions are exactly on the Paris meridian. The Paris meridian is the lesser known brother of the Greenwich meridian. And both have a whole family of different meridians. For a long time there was no standard meridian and it was not necessary. A mapmaker could choose his own meridian and as long as he used it consistently over his own maps, the maps were mutually connectable. In the seventeenth century, the map meridian was preferably placed in the Atlantic Ocean so that there was no east-west confusion about land. The Greenwich meridian has become the standard for the map and for standard time measurement. But the Greenwich and Paris meridians were therefore not competitors. Every city, or at least every country, had its own meridian to determine the local time and thus the time for the land (As the Nanjing meridian was used for the time in China). Until recently, there was no universal global time standard. Time was determined locally by measuring the passage of the sun and stars through the local meridian. So a local meridian was needed for time calculation.

arago03.jpg The meridian of Paris was first of all the basis for the meter and has also been used as a reference for maps for a long time. The French wanted that piece of history not to be completely forgotten. When they organized a competition for a new monument to Arago, a Belgian artist submitted the idea to plot the meridian through the city. The medallions have been placed on the sidewalks on the street. It provides a special walk where you walk as straight as possible through Paris through streets that you would otherwise not come as a tourist.

vert01.jpg Outside Paris the meridian extends even further and is indicated by a row of trees as la méridienne verte. In Paris this is not indicated by a row of trees but by a series with a number of medallions such as the Arago medallions, in the Jardin de Luxembourg you can see a few. La méridienne runs all the way from Dunkirk to the Pyrenees, the part that was originally measured with triangulation to determine the meridian and to determine the meter.

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en/plaatsen/meridiaan_van_parijs.txt · Last modified: 2020/12/29 13:21 (external edit)