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.

Biology

• Subfossil bones of the Rodrigues solitaire are discovered.

Linguistics

• 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 mathematica circa transformationem aequationum algebraicarum, proposing algebraic solutions to quintic functions.
• Lagrange moves from Prussia to Paris under the patronage of Louis XVI of France.
• William Playfair produces the first line and bar charts.

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 Ueber des Anquicken der gold- und silberhältigen Erze, published in Vienna.
• Scottish millwright Andrew Meikle invents a practical threshing machine.

Awards

• Copley Medal: Not awarded^[1]

Births

• January 5 – Thomas Nuttall, English naturalist (died 1859)
• February 26 – François Arago, French mathematician, physicist and astronomer (died 1853)
• February 28 – Christian Ramsay, Scottish botanist (died 1839)
• April 16 – Thomas Sewall, American anatomist (died 1845)
• April 28 – Elizabeth Andrew Warren, Cornish botanist and marine algolologist (died 1864)
• July 24 – Joseph Nicollet, French geographer, explorer, mathematician and astronomer (died 1843)
• November 3 – Ernst Friedrich Germar, German entomologist (died 1853)
• December 6 – Johann Georg Bodmer, Swiss mechanical engineer and inventor (died 1864)

Deaths

• February 25 – Thomas Wright, English astronomer, mathematician, instrument maker, architect, garden designer, antiquary and genealogist (born 1711)
• May 2 – Petronella Johanna de Timmerman, Dutch scientist (born 1723)
• May 4 – Leonardo Ximenes, Tuscan polymath (born 1716)
• May 15 – Eva Ekeblad, agronomist, first woman in the Swedish Royal Academy of Science (born 1724)
• May 21 – Carl Wilhelm Scheele, Swedish chemist (born 1742)
• October 16 – Alexander Wilson, Scottish polymath (born 1714)
• November 10 – John Hope, Scottish physician and botanist (born 1725)