The year 1786 in science and technology involved some significant events.

Astronomy

January 17 - Pierre Méchain first observes Comet Encke, from Paris.
August 1 - Caroline Herschel becomes the first woman to discover a comet.

Herschel , First Catalog of Nebulae

Lingustics

February 2 - In a speech before The Asiatic Society in Calcutta, Sir William Jones notes the formal resemblances between Latin, Greek, and Sanskrit, laying the foundation for comparative linguistics and Indo-European studies.

Mathematics

Erland Samuel Bring publishes Meletemata quaedam mathematematica circa transformationem aequationum algebraicarum, proposing algebraic solutions to quintic functions.
Lagrange moves from Prussia to Paris under the patronage of Louis XVI of France.

Technology

August - James Rumsey tests his first steamboat in the Potomac river at Shepherdstown, Virginia.
Ignaz von Born introduces a method of extracting metals using the patio process in his Uber des Anquicken der Erze.

Awards

Copley Medal: Not awarded

Births

January 5 - Thomas Nuttall, English naturalist (d. 1859)
February 26 - François Arago, French mathematician, physicist, and astronomer (d. 1853)

25 October 1786 Birth of Charles Mason in Philadelphia, Pennsylvania, USA

Deaths

February 22 - Death of Thomas Wright, Byers Green near Durham, England, English astronomer (b. 1711)
May 4 - Leonardo Ximenes, Tuscan polymath (b. 1716)
May 15 - Eva Ekeblad, agronomist, first woman in the Swedish Royal Academy of Science (b. 1724)
May 21 - Carl Wilhelm Scheele, Swedish chemist (b. 1742)

1786 Death of Alexander Wilson

1786 Death of John Goodricke