A meeting held between the founding 14 members of the Royal Astronomical Society, including Charles Babbage and John Herschel at the Freemasons' Tavern. The first president of the society, Frederick William Herschel, never actually took the chair in any meetings.

Sources:

https://www.rmg.co.uk/stories/topics/astronomy-19th-century

https://ras.ac.uk/about-the-ras/a-brief-history

https://ras.ac.uk/timeline