- Sep 5 Jean-Étienne Montucla, French mathematician, born in Lyon, France (d. 1799)
- Sep 12 Guillaume Le Gentil, French astronomer, born in Coutances, France (d. 1792)
- Sep 16 Nicolas Desmarest, French geologist and geographer (Volcanos), born in Soulaines-Dhuys, France (d. 1815)
- Sep 24 Arthur Guinness, Irish brewer and founder of the Guinness brewery, born in Celbridge, County Kildare, Ireland (d. 1803)
- Sep 29 Robert Clive, English explorer and founder (British Empire in India), born in Styche, England (d. 1773)