Gnomon in the Saint-Sulpice church.

The obelisk, the meridian brass line on the floor.

Rose Line is a fictional name given to the Paris Meridian and to the sunlight line defining the exact time of Easter on the Gnomon of Saint-Sulpice, marked by a brass strip on the floor of the church in the Priory of Sion mythology, where the two are conflated.

The fictional name Rose Line was also popularized by Dan Brown in his 2003 novel, The Da Vinci Code.^[1]

[edit] Priory of Sion Mythology

The 1967 Priory of Sion document Au Pays de la Reine Blanche^[2][3] states that "Rennes-les-Bains is located precisely on the Zero Meridian, which connects Saint-Sulpice in Paris" adding that "the parish of Rennes-les-Bains guards the heart of Roseline", being a reference to Saint Roseline de Villeneuve. Au Pays de la Reine Blanche also referred to "the line of the Zero Meridian, that is to say the red line, in English: 'Rose-line'".^[4] Later in 1978, Pierre Plantard also referred to the "red line of the meridian, the 'Rose-Line'...since Roseline, the Abbess of the 'Celle aux Arcs', celebrates her feast day on 17 January... and her legend is well worth a read".^[5]

The document entitled Le Serpent Rouge - Notes sur Saint-Germain-des-Près et Saint-Sulpice de Paris^[6] conflates the Paris Meridian with a gnomon in the Parisian church of Saint-Sulpice marked in the floor with a brass line, which it calls the "Red Serpent".

Philippe de Chérisey in his document Stone and Paper recounted a story that a Roseline was also the name of his acquaintance: "there was a Roseline I knew who died on 6 August 1967, on the Feast of the Transfiguration, when leaving the zero meridian by car."^[7] Another document by Philippe de Chérisey entitled Circuit,^[8] in Chapter VII, adds the detail that Roseline was killed in a car accident whilst working as a double on the Television film La beauté sur la terre (1968),^[9] a film that also starred Philippe de Chérisey under his stage name of Amédée.^[10] The story about Roseline in Circuit also involves an imaginary character named Charlot who appears frequently throughout Circuit and both characters are patently imaginary beings appearing in one of Philippe de Chérisey's surrealist compositions.

Chapter XIII of Circuit is devoted to the Zero Meridian, with de Chérisey claiming it was established by Till Eulenspiegel (before Jean Picard), listing key sites that it passes through (in a fictional work attributed to Abbé François-Pierre Cauneille). In this chapter Roseline is called 'Fisher Woman', preferring herself to be known as "Di O Nysos, DON" ("dondon" is French slang for "fat woman"), an otherworldly being who organises funerals for the dead who are still living in her new Citroen 2CV (the make of car she was killed in).

[edit] Dan Brown's The Da Vinci Code

The term Rose Line has been popularized by Dan Brown in his novel The Da Vinci Code as an alternate name for "the world's first prime meridian",^[1] identified as the Paris Meridian.^[11] Brown's novel also conflates this meridian with a gnomon in the Parisian church of Saint-Sulpice marked in the floor with a brass line,^[12] as did the 1967 Priory Document Le Serpent Rouge - Notes sur Saint-Germain-des-Près et Saint-Sulpice de Paris. The Paris Meridian actually passes about 100 metres east of the gnomon,^[13] which according to author Sharan Newman and a sign in the church was "never called a Rose-Line".^[12][14] A St Sulpice booklet dating from 2000, in the page about the history of the gnomon describes the brass line as "a meridian", it does not use the term Roseline or Rose Line.^[15] Author Paul Murdin describes such sun lines as a "Meridian", or meridiana.^[16]

Brown identified the Paris Meridian with the alleged bloodline of Jesus Christ and Mary Magdalene as well as Rosslyn Chapel, the central part of his novel. Quoting from The Da Vinci Code:

"Rosslyn Chapel's entrance was more modest than Langdon expected. The small wooden door had two iron hinges and a simple oak sign, Roslin. This ancient spelling, Langdon explained to Sophie, derived from the Rose Line meridian on which the chapel sat; or, as Grail academics preferred to believe, from the 'Line of the Rose' — the ancestral lineage of Mary Magdalene..."^[17]

Quoting Mark Oxbrow and Ian Robertson from their book Rosslyn and the Grail:

"Dan Brown simply invented the 'Rose Line' linking Rosslyn and Glastonbury. The name 'Roslin' definitely does not derive from any 'hallowed Rose Line'. It has nothing to do with a 'Rose Bloodline' or a 'Rose Line meridian'. There are many medieval spellings of 'Rosslyn'. 'Roslin' is certainly not the 'original spelling': it is now the most common spelling for the village."^[18]

At the climax of the novel, the protagonist follows the line of Arago medallions to the Louvre museum, where (according to the book) the Paris Meridian passes beneath the so-called Inverted Pyramid in an underground mall in front of the museum. Following the tradition of esoteric interpretations of this meridian, the novel hints that this is the final resting place of the Holy Grail. The fact that the meridian passes near the Inverted Pyramid is also noted in the book Le guide du Paris maçonnique by Raphäel Aurillac, who likewise ascribes some deeper, esoteric significance to this.

In the Louvre area, the meridian line marked by the Arago medallions actually runs through the museum and the great courtyard at a spot considerably to the east of the Inverted Pyramid. The medallions in the museum are behind ticketed access points, while the Inverted Pyramid is located in a public mall next to the museum.

Other landmarks said to lie on the line are Arques and Conques,^[19] the Lady of the Roses cathedral in Rodez, St. Vincent's in Carcassonne, and the Church of St. Stephen's in Bourges, and Rennes-les-Bains.

While Dan Brown presents the Rose Line as "the world's first prime meridian",^[1] the idea of establishing a Prime Meridian dates back to antiquity,^[20] with suggested meridians running through Rhodes or the Canary Islands. When Greenwich was adopted as the universal zero longitude in 1884^[21] (not 1888 as the novel says), it had at least nine rivals besides Paris (Berlin, Cadiz, Copenhagen, Lisbon, Rio, Rome, Saint Petersburg, Stockholm, and Tokyo).