John Winthrop (December 19 1714 – May 3 1779) (not to be confused with his great-great-great-grandfather John Winthrop, founder of the Massachusetts Bay colony) was the 2nd Hollis Professor of Mathematics and Natural Philosophy in Harvard College. He was a distinguished astronomer, and corresponded regularly with the Royal Society in London — one of the first American intellectuals to be taken seriously in Europe. He was noted for attempting to explain the great Lisbon earthquake of 1755 as a scientific (rather than religious) phenomenon, and for making (date?) a trip to Nova Scotia in an attempt to observe an eclipse there.
He served as acting president of Harvard in 1769 and again in 1773; but both times he declined the offer of the full presidency on grounds of old age.