Francis Potter

Francis Potter (1594–1678) was an English painter, clergyman, Biblical commentator, and experimentalist, and an early Fellow of the Royal Society.

His friend John Aubrey describes him as "like a monk", and as "pretty long visaged, and pale clear skin, gray eie".

Potter formed a theory of the Number of the Beast, connecting 25, the approximate square root of 666, with Catholic institutions; he elaborated it in a manuscript which was read in 1637 by Joseph Mead, who commended it as a wonderful discovery to Samuel Hartlib.

It was published as An Interpretation of the Number 666 (Oxford, by Leonard Lichfield, 1642), with a symbolical frontispiece, an opinion by Mead prefixed, and a preface dated from Kilmington.

It has been suggested that Potter's priority in practical work on blood transfusion, as hinted by Timothy Clarke, is more significant than has been admitted in the past.