Abraham Sharp

Abraham Sharp (about 1653 to 18 July 1742) was an English mathematician and astronomer, born at Horton Hall in Little Horton near Bradford, the son of a well-to-do merchant. After an apprenticeship in the cloth trade and a spell teaching writing and commercial arithmetic in Liverpool, he moved to London, where his knowledge of mathematics brought him to the attention of John Flamsteed. At the Royal Observatory Greenwich he worked as assistant and instrument maker, engraving the scale of the great mural arc and producing eclipse data and tables of the motions of Jupiter's satellites, and he showed great skill as a calculator. He published Geometry Improved and logarithmic tables, and calculated pi to 72 decimal places using an arctangent series, briefly holding the record until John Machin reached 100 digits in 1706. He returned to Little Horton in 1694, where he became something of a recluse, and the lunar crater Sharp is named after him.