A Southern Meridian: Astronomical Undertakings in the Eighteenth-Century Spanish Empire

Abstract

In a treatise on geographical history published in 1752, Father Murillo, a Spanish Jesuit, reviewed the different places used as references for calculating longitude; in other words, where the ‘prime meridian’ had been situated throughout history: Pytheas of Marseille began from Thule or Iceland; Eratosthenes, followed by the Arabs, from the Pillars of Hercules or the Strait of Gibraltar; Hondius from the Hesperides or Cape Verde; Gerardus Mercator from between the islands of Corvo and Flores; Ptolemy from the Canary Islands; Blaeu, who was followed by the Dutch, from the island of Tenerife; Ricciolo from the island of La Palma. The French, by order of Louis XIII, placed the Prime Meridian for the measurement of longitude on the island of El Hierro […] Now the English have moved it again to London, and not to be outdone the French have set it in Paris. And one day they will put the equinox and the tropics in London or Paris.1