Detail map of Paris, Île-de-France, France,Montredon-Labessonnié, Occitanie, France Overview map of Paris, Île-de-France, France,Montredon-Labessonnié, Occitanie, France

A: Paris, Île-de-France, France, B: Montredon-Labessonnié, Occitanie, France

Guillaume de Castelfranc Issues the First World Map Showing Isogonic Lines

1602 to 1604
<p>This copy of de Castelfranc's map in the book by Nautonier sold at Christie's for 24,250 Euros in 2008.</p>

This copy of de Castelfranc's map in the book by Nautonier sold at Christie's for 24,250 Euros in 2008.

During 1602 and 1604 French astronomer and geographer Guillaume de Castelfranc, called Le Nautonier, published the first world map that showed isogonic lines, or lines of geomagnetism. The map appeared in his Mecometrie de l’eymant, c’est a dire la maniere de mesurer les longitudes par le moyen de l’eymant. Par laquelle est enseigné, un tres certain moyen, au paravant inconnu, de trouver les longitudes geographiques de tous lieux,--aussi facilement comme la latitude. Davantage, y est monstree la declinaison de la guideymant, pour tous lieux. Oeuvre nécessaire aux admiraux, cosmographes, astrologues, geographes, pilotes, geometriens, ingenieux, mestres des mines, architectes, et quadraniers. De linvention de Guillaume de Nautonier sieur de Castelfranc en Languedoc ..., imprimé à Venes ches l'autheur par Raimond Colomies, imprimeur en l'Université de Tolose, & par Antoine de Courteneufve. Castelfranc's map was used in work on finding longitude by means of magnetic variation. The tables give the world distribution of the variation, by latitude, along each of the meridians.

There must have been an unusually large international demand for Castelfranc's book as in 1603 editions appeared in Latin, Castilian, English and Dutch. The first part was dedicated to Henri IV of France, the second to James I of England , and the third to Maximilien de Béthune, Duke of Sully and Grand master of artillery, and superintendent of fortifications. The work was used in 1603 by Samuel de Champlain for his cartographic work in New France

Friend, Valero-Mora, and Ibáñez Ulargui, "The First (Known Statistical Graph: Michael Florent van Langen and the 'Secret of Longitude." 2010. http://www.datavis.ca/papers/langren-TAS09154.pdf, accessed 01-08-2013.

Shirley, Mapping of the World, 240.

(This entry was last revised on 03-03-2015.)

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