I was a Professor of Astronomy at Gresham College, London.
I am best known for developing in 1706 a quickly converging series for pi, which I used to compute pi to 100 decimal places.
My formula [pi = 16 arttan(1/5) - 4 arctan(1/239)] for calculating pi was so good and fast that it became the primary tool of pi-hunters for centuries, even with the advent of computers.
I was a member of the 1712 commission which tried to resolve the calculus priority dispute between Leibniz and Newton.
Except for my formula for pi, my other professional work is considered to be of medium to low in quality...yet some claim that I had a "considerable influence of the development of mathematics in England."
John Machin (1680óJune 9, 1751)