Mercator 1569 world map
Mercator publishes his navigational world map on a new projection
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Original prompt & settings (JSON) ↗Mercator left no formula explaining how he spaced the parallels. Usable mathematical tables followed roughly thirty years later.
August 1569, at Duisburg
In August 1569 Gerardus Mercator published at Duisburg a world wall map titled Nova et aucta orbis terrae descriptio ad usum navigantium emendate accomodata.
It arrived as 18 sheets that assembled into a wall map. The Bibliothèque nationale de France copy measures 200 × 133 cm, at a scale of about 1:20,205,000.
The surviving catalogue record establishes the month but not a publication day.
Why the parallels spread out
The map used straight, parallel meridians and progressively increased the spacing between parallels toward the poles.
That spacing made rhumb lines — courses maintaining a constant compass bearing — appear as straight lines, which is the defining navigational property of the projection.
A straight line on such a chart is a constant-bearing rhumb line, not generally the shortest route between two places. The projection also sends the poles to infinity, so no complete Mercator world map can show them.
Not an overnight change
Mercator did not publish his construction method with the map, leaving later cartographers to reconstruct and mathematically explain it. Modern reconstructions of his exact procedure remain debated.
Edward Wright's Certaine Errors of Navigation, in 1599, supplied the mathematical tables and explanation that helped make Mercator charts reproducible.
Adoption was gradual. Seventeenth-century mariners continued using plane charts, and the 1569 publication did not solve the separate problems of finding longitude or correcting for magnetic declination.
Sources
Researched 24 Aug 2026 4 sources not yet audited Date corrected
How this was checked
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Date corrected. The research places this at 1569-08.
What the sources leave uncertain
- The surviving catalogue record establishes August 1569 but not a publication day.
- Mercator did not explain how he calculated the parallel spacing. Modern reconstructions of his exact construction method remain debated.
- Earlier maps, including one by Erhard Etzlaub, used related expanding-latitude arrangements; 1569 is securely the first presentation of the projection conventionally called Mercator’s.