Mathematician:D.F. Ferguson

Mathematician
Calculated approximations to the value of $\pi$ (pi), using a mechanical desk calculator, to:
 * $620$ digits in $1945$ (or $1946$; sources are inconsistent), finding an error in the work of in the $528$th digit
 * $710$ digits in January $1947$
 * $808$ digits in September $1947$
 * $1120$ digits in September $1949$, with, using an electro-mechanical calculator.