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The Medieval 32 Point Compass Rose

Finely engraved wind chart, surrounded by wind heads and with the compass divided into 32 parts and text in six languages.

The wind heads are arranged in successive ages from young to old, and four large heads, blowing winds on the compass and seasons.

The corners are decorated with large allegorical representations of the four seasons.

The 32 Point Compass Rose in Medieval Navigation

The map illustrates the classical 32 point compass rose, as used in Medieval times by mariners at sea.

Arab navigators in the Red Sea and the Indian Ocean, who depended on celestial navigation, were using a 32-point sidereal compass rose before the end of the 10th century.  In the northern hemisphere, the steady Pole Star (Polaris) was used for the N-S axis; the less-steady Southern Cross had to do for the southern hemisphere, as the southern pole star, Sigma Octantis, is too dim to be easily seen from Earth with the naked eye. The other thirty points on the sidereal rose were determined by the rising and setting positions of fifteen bright stars.  

The western half of the rose would be the same stars in their setting position. The true position of these stars is only approximate to their theoretical equidistant rhumbs on the sidereal compass. Stars with the same declination formed a "linear constellation" or kavenga to provide direction as the night progressed.

A similar sidereal compass was used by Polynesian and Micronesian navigators in the Pacific Ocean, although different stars were used in a number of cases, clustering around the East-West axis.

The 32-point compass used for navigation in the Mediterranean by the 14th century, had increments of 11​1⁄4° between points. Only the eight principal winds (N, NE, E, SE, S, SW, W, NW) were given special names. The eight half-winds just combined the names of the two principal winds, e.g. Greco-Tramontana for NNE, Greco-Levante for ENE, and so on. Quarter-winds were more cumbersomely phrased, with the closest principal wind named first and the next-closest principal wind second, e.g. "Quarto di Tramontana verso Greco" (literally, "one quarter wind from North towards Northeast", i.e. North by East), and "Quarto di Greco verso Tramontana" ("one quarter wind from NE towards N", i.e. Northeast by North). Boxing the compass (naming all 32 winds) was expected of all Medieval mariners.

Jan Jansson Biography

Jan Janssonius (also known as Johann or Jan Jansson or Janszoon) (1588-1664) was a renowned geographer and publisher of the seventeenth century, when the Dutch dominated map publishing in Europe. Born in Arnhem, Jan was first exposed to the trade via his father, who was also a bookseller and publisher. In 1612, Jan married the daughter of Jodocus Hondius, who was also a prominent mapmaker and seller. Jonssonius’ first maps date from 1616.

In the 1630s, Janssonius worked with his brother-in-law, Henricus Hondius. Their most successful venture was to reissue the Mercator-Hondius atlas. Jodocus Hondius had acquired the plates to the Mercator atlas, first published in 1595, and added 36 additional maps. After Hondius died in 1612, Henricus took over publication; Janssonius joined the venture in 1633. Eventually, the atlas was renamed the Atlas Novus and then the Atlas Major, by which time it had expanded to eleven volumes. Janssonius is also well known for his volume of English county maps, published in 1646.

Janssonius died in Amsterdam in 1664. His son-in-law, Johannes van Waesbergen, took over his business. Eventually, many of Janssonius’ plates were sold to Gerard Valck and Pieter Schenk, who added their names and continued to reissue the maps.