  This article describes the life and work of Willem Janszoon Blaeu
(1571-1638), who founded one of history's greatest cartographic publishing
firms in 1599. Mostly renowned as a cartographer, he also made terrestrial and
celestial globes, various instruments such as quadrants, a planetarium and a
tellurium. He invented mechanical devices for improving the technics of
printing. As an astronomer, a former student of Tycho Brahe, Willem Blaeu made
careful observations of a moon eclipse, he discovered a variable star now known
as P Cygni, and carried out a measurement of a degree on the surface of the
earth (as his countryman Snell did in 1617).
