1786 in science

Astronomy

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

Biology

• Subfossil bones of the Rodrigues solitaire are discovered.

Exploration

• Summer – English captain George Dixon begins a year-long exploration of the shores of modern-day British Columbia and southeastern Alaska. He spends the intervening winter in the Hawaiian Islands, where he becomes the first European to visit the island of Molokaʻi.

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.
• Joseph Louis Lagrange moves from Prussia to Paris under the patronage of King Louis XVI.
• 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

Births

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

Deaths

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