June 3 – Transit of Venus is observed from many places in order to obtain data for measuring the distance from the Earth to the Sun. Those taking part include
Guillaume Le Gentil in Pondicherry, India: Le Gentil had hoped to go to Manila in the Philippines but was turned away by the local Spanish colonial governor. The weather in Pondicherry is cloudy that day. Le Gentil had also missed the 1761 transit through bad luck.
April 29 – James Watt is granted a Britishpatent for "A method of lessening the consumption of steam in steam engines" – the separate condenser,[2] a key improvement (first devised by Watt in 1765) which stimulates the Industrial Revolution.[3] In September he completes a full-size experimental engine at Kinneil House in Scotland.