Isaac Newton experiments with gravity in 1665:…
September 1665 CE
Isaac Newton experiments with gravity in 1665: he is home in Lincolnshire due to the plague-related summer closing of Cambridge University.
The twenty-two-year-old Newton's mathematical work will be said "to distinctly advance every branch of mathematics then studied" (W. W. Rouse Ball (1908), "A short account of the history of mathematics", at page 319).
Newton's early work on the subject usually referred to as fluxions or calculus, can be seen, for example, in a manuscript of October 1666, now published among Newton's mathematical papers.