Decorative double hemisphere star chart from Van Keulen's, "Boeck zee-Kaardt," published in Amsterdam in 1680.
This double hemisphere celestial chart by Louis Vlasbloem, called Ludovico Vlasblom on the chart, is derived from the celestial hemispheres in Joan Blaeu's world map. The small spheres depict the geo-centric and helio-centric configurations of the solar system. The very energetic expansion of Dutch maritime trade in the late 16th century and first two thirds of the 17th century provided new astronomical knowledge of the Southern hemisphere, and in 1598 twelve new constellations formed by Petrus Plancius appeared on a Hondius globe. These were added to the Ptolemaic canon of 48 constellations making a total of 60. The newly discovered constellations of the southern hemisphere include: Pavo, Phoenix, Indus, and others, and Coma Berenices in the north.
Kanas notes that Blasbloem was a physician and mathematician who around 1675 produced a pair of celestial hemispheres that was later bound into a number of sea atlases by Van Keulen, with the additional imprint. The maps are centered on the ecliptical pole, using a stereographic projection with external orientation. The map is nearly identical to Joan Blaeu's rare celestial plan.
The present example is a fine dark impression, in full original color.