The Paris meridian is a meridian line running through the Paris Observatory in Paris, France – now longitude 2°20′14.02500″ East. It was a long-standing rival to the Greenwich meridian as the prime meridian of the world. The "Paris meridian arc" or "French meridian arc" is the name of the meridian arc measured along the Paris meridian.
Meridian Room (or Cassini Room) at the Paris Observatory, 61 avenue de l'Observatoire (14th arrondissement). The Paris meridian is traced on the floor.
The triangulation mesh of the Anglo-French survey 1784–1790
The West Europe-Africa Meridian-arc extending south from the Shetland Islands, through Great Britain, France and Spain to El Aghuat in Algeria, whose parameters were calculated from surveys carried out in the mid to late 19th century. It yielded a value for the equatorial radius of the Earth a = 6 377 935 metres, the ellipticity being assumed as 1/299.15. The radius of curvature of this arc is not uniform, being, in the mean, about 600 metres greater in the northern than in the southern part. The
One of the 135 Arago medallions. This one is located near the Louvre Pyramid.
The Paris Observatory, a research institution of the Paris Sciences et Lettres University, is the foremost astronomical observatory of France, and one of the largest astronomical centers in the world. Its historic building is on the Left Bank of the Seine in central Paris, but most of the staff work on a satellite campus in Meudon, a suburb southwest of Paris.
Paris Observatory
Paris Observatory
The Château-Neuf at Meudon in 1871, after the fire.
Project for a dome in the heart of the Château-Neuf, never built. Circa 1880
