Charles Mason
Charles Mason (25 April 172825 October 1786) was an English astronomer who made significant contributions to 18th-century science and American history, particularly through his survey with Jeremiah Dixon of the Mason–Dixon line, which came to mark the border between Maryland and Pennsylvania (1764–1768). The border between Delaware and Maryland is also defined by a part of the Mason–Dixon line. Early career Mason's early career was spent at the Royal Greenwich Observatory near London. He served as assistant astronomer from 1756 to 1760 under the Reverend James Bradley, the third Astronomer Royal. While employed at the Greenwich Observatory, Mason became familiar with Professor Tobias Mayer's Tables of the Moon. The Lunar Tables were designed to solve the problem of determining longitude at sea, a challenge that frustrated scientists and navigators for decades. Mason worked throughout his life to perfect the Lunar Tables as a method of improving navigation at sea. In 1787, Mason's work was recognized, and he was awarded £750 (not the full prize of £10,000 to £20,000) by the Board of Longitude for his work on perfecting the Tables. 1761 transit of Venus In 1761, Mason was assigned to travel to the island of Sumatra to observe the transit