This highly unusual map shows the world projected from the North Pole as if it were the table of a sundial. The point of a sundial is called a gnomon, and this projection is therefore known as a gnomonic of sundial projection. The landmasses are drawn to scale in proportion to their distance from the pole. The result is a very distorted, though mathematically correct, projection. The map is surrounded by horological diagrams that show ways to measure and record the passage of time.

Double-page engraved copperplate map of the world, on a gnomonic (central), or sundial, projection. 

 was a mathematician from Nuremberg who published the first map on a gnomonic projection. An ancient technology used by Greek mariners as early as the sixth century BCE, this projection displays all great circles as straight lines, resulting in any straight-line segment showing a geodesic, the shortest route between the segment's two endpoints. 

Ritter's plates for maps were intended to be used as sundials, hence very few have survived. Based on the precise unique gnomonic projection for each location of the sundial, lines of bearing could be drawn with an extended piece of string. The map is surrounded by ten diagrams that show how to measure and record the passage of time.

Ritter specialized in the design and manufacture of astrolabes, sundials, and other astronomical, horological, and cartographical instruments. His ‘Speculum Solis’ (‘Mirror of the Sun’) from which this map derives, was a work on sundials that contained unusual maps on gnomonic projection. Interestingly, Ritter's plates were intended to be used as sundials – based on the precise unique gnomonic projection for each location of the sundial, lines of bearing could be drawn with an extended piece of string. Very few copies survive.

This highly unusual map shows the world projected from the North Pole. The projection, called a gnomonic or sundial projection, is named after the central point of a sundial. The landmasses are drawn to scale in proportion to their distance from the pole. The result is very distorted, though mathematically correct. The map is surrounded by horological diagrams that show ways to measure and record the passage of time.

Ritter's World Map