Oronce Fin矇 (December 20, 1494 - August 8, 1555) was a French mathematician and cartographer. Primarily a popularizer, he was one of the most prolific authors of mathematical books of his age. He worked in a wide range of mathematical fields, including practical geometry, arithmetic, optics, gnomonics, astronomy, and instrumentalism. He gave the value of pi (= 3.1416) to be (22 2/9)/7 = 3.1746 in 1544. Later, he gave 47/15 = 3.1333 and, in De rebus mathematicis (1556), he gave 3 11/78 = 3.1410. In 1542 he published De mundi sphaera (On the Heavenly Spheres), a popular astronomy textbook whose woodcut illustrations. His writing on astronomy included guides to the use of astronomical equipment and methods. He also described more recent innovations, such as an instrument he called a m矇th矇oroscope (an astrolabe modified by adding a compass). His heart-shaped (cordiform) map projection may be his most famous illustration, and was frequently employed by other notable cartographers, including Peter Apian and Gerardus Mercator. He died in 1555 at the age of 60.