Map from Imago Mundi

He (Roger Bacon) postulated a spherical earth through which, for geometric orientation, he drew three mutually perpendicular lines meeting at the center, thus creating x, y, and z axes. For geographic division, he divided the sphere into quarters with two circumferences, one around what later became the equator, and another through the poles. He then assumed that every place on earth was the apex of a cone, and used coordinates of objects in the heavens to project these apexes onto the earth, a theoretical navigator plotting by the stars. He thus became the first man since Ptolemy (although he did not know it) to advocate the use of coordinates to identify cities, rivers, mountains and boundaries.

Bacon went further, producing a large map on which were plotted the coordinates of many of the cities of Europe, He used Toledo as a base and then crated a grid to show relative distance and location to much of the known world. That does not mean he was always right. As to the unknown world, Bacon ascribed to Aristotle’s erroneous assertion that “the sea between the west of Spain and the eastern edge of India is of no great extent.”

The original of Bacon’s map does not survive, but a plagiarized version may have changed the course of history. Bacon’s geographic theories found their way, almost verbatim – and without attribution – into a treatise entitled “Imago Mundi” by one Cardinal Pierre D’Ailly. D’Ailly’s work, which was written in the early 1400s but not published until the late 1480s, contained a large map exactly like the one bacon had described in the ‘Opus Majus’. Sometime in the late 1480s, the Imago Mundi was read with great interest by an obscure Italian navigator named Christopher Columbus, who made almost nine hundred handwritten notations in the margins. The great nineteenth-century geographer Alexander von Humboldt believed that Bacon’s passage about the size of the Atlantic Oceans was key to Columbus’s undertaking his journey west. (There are those who claim that Columbus might not have read the work until 1494. If so, it seems odd that Columbus would take such interest in a theoretical document the varacity of which he had already tested.)

The question of whether or not he influenced Columbus aside, Bacon’s use of mathematics to overlay geography revolutionized the science. He observed that at some places along a line is Egypt, no shadow was cast, while to one side of the line, shadows were cast northward, to the other side, southward. He further noted that in some of these locations, no shadow was cast twice a year (Tropic of Cancer and Capricorn). In discussing that part of the earth that is habitable, Bacon broke from Ptolemy. “I therefore insist that, though the habitable world known to Ptolemy and his followers is squeezed into a quarter of the total, far more than a quarter is, in fact, fit for habitation”

Many of these regions, Bacon went on, were not only habitable but ‘habitated’. “There is a boundless advantage in the knowledge of the places in the world for philosophy, theology, and the Church of God.” He wrote. ~ Pages 144 to 146 (Friar and the Cipher)