Engraving by Dequevauviller drawn by Duchemin, after an original work by Hans Holbein the Younger, 1528. At the age of 30 Kratzer (1487-c 1550) moved to England where Cardinal Wolsey (1475-1530) employed him to teach mathematics at Oxford University. While there he also made sundials, including one he made for the Cardinal. Kratzer was a friend of Holbein (1497-1543), who was Henry VIII's (1491-1547) court painter, and Kratzer became Henry's astrologer. In the 16th century astronomy and astrology were more similar than they are now, being regarded as two branches of the same science.
© Science Museum / Science & Society Picture Library