Rene Descartes (1596-1650), French mathematician, teaching astronomy to Queen Christina of Sweden (1626-1689). Descartes accepted a post at Christina's court in Stockholm in September 1649. Christina insisted that Descartes teach her three times a week at five o'clock in the morning. Descartes had habitually never risen from bed before 11am and had also suffered from ill-health throughout his life. The early, cold mornings caused him to catch pneumonia and he was dead by February 1650. In astronomy, Descartes tried unsuccessfully to find a compromise between the cosmological work of Ptolemy and Copernicus.