Abraham Sharp

Abraham Sharp was an English mathematician and astronomer, born around 1653 at Horton Hall in Little Horton, Bradford, the son of a well-to-do merchant, and educated at Bradford Grammar School. After a merchant's apprenticeship he worked as a schoolmaster in Liverpool and a bookkeeper in London, until his knowledge of mathematics and astronomy drew the attention of John Flamsteed, who in 1688 brought him to the Royal Observatory at Greenwich. There he improved instruments, showed great skill as a calculator and published Geometry Improved and logarithmic tables. Using an arctangent series he calculated pi to 72 decimal places, briefly holding the record until John Machin reached 100 digits in 1706. He returned to Little Horton in 1694, designed two planispheres for the Atlas Coelestis, and died there in 1742, unmarried. A lunar crater bears his name.