December: Franklin began designing the Pennsylvania fireplace
February 5: Franklin advertised an early version of the Pennsylvania fireplace for sale.
May 14: Franklin published his “A Proposal for Promoting Useful Knowledge Among the British Plantations in America”, the founding document of the American Philosophical Society
September 11: Sarah (“Sally”) Franklin born to Benjamin Franklin and Deborah Read.
January 16: Josiah Franklin (Franklin's father) died, aged 87.
April: Peter Collinson sent a glass tube, together with a pamphlet describing the recent German electrical experiments to the Library Company, thus starting Franklin's electrical experiments.
January 17: Franklin turned 40
March 16: Joseph Breintnall, Franklin’s close friend, drowned himself in the Delaware River
May 25: Franklin wrote a letter to Peter Collinson in England, describing his first experiments with electricity
November 17: Franklin authored and published a pamphlet “Plain Truth,” on the need for protecting Philadelphia against the raids of French and Spanish privateers on the Delaware River.
November 24: Franklin and others organized a volunteer militia – the Associators – for the defense of Pennsylvania
January 1: Aged 42, Franklin entered into a partnership with David Hall and retired from printing. In exchange for the use of the shop and its printing presses, Hall agreed to divide the profits evenly with Franklin.
October 23: Franklin authored and published the pamphlet “Proposals Relating to the Education of Youth in Pennsylvania”
November 14: Franklin and others organized the “Academy of Philadelphia” (later to become the University of Pennsylvania); Franklin elected President of the Academy’s Trustees.