1787 in science

Astronomy

• January 11 – William Herschel discovers Titania and Oberon, the first moons of Uranus found.
• February 19 – First light for William Herschel's 40-foot telescope under construction at Observatory House, Slough, England.
• Caroline Herschel is granted an annual salary of £50 by King George III of Great Britain for acting as assistant to her brother William in astronomy.

Biology

• William Curtis begins publication of The Botanical Magazine; or Flower-Garden Displayed in London. As Curtis's Botanical Magazine, it will still be published into the 21st century.
• Spanish physician Francisco Xavier Cid publishes Tarantismo Observado en España, a study of tarantulas and the tarantella as a cure for their bite.
• King George III of Great Britain, writing as Ralph Robinson of Windsor, contributes to Arthur Young's Annals of Agriculture.

Chemistry

• Guyton de Morveau, Jean-Henri Hassenfratz, Antoine François, Antoine Lavoisier, Pierre Adet and Claude Berthollet publish in Paris.
• Jacques Charles proposes Charles's law, a corollary of Boyle's law, describes relationship between temperature and volume of a gas.

Physics

• Ernst Chladni publishes Entdeckungen über die Theorie des Klanges, demonstrating modes of vibration.
• Jean-Paul Marat publishes the first French translation of Newton's 'Opticks'

Surveying

• The first great theodolite constructed by Jesse Ramsden for the Anglo-French Survey (1784–1790) linking the observatories of Paris and Greenwich.

Technology

• June – William Symington patents improvements to the Watt steam engine.
• c. July – John Wilkinson launches an iron barge in the English Midlands.
• August 27 – Launching a steam-powered craft on the Delaware River, John Fitch demonstrates the first United States patent for his design.
• December 3 – James Rumsey demonstrates a water-jet propelled boat on the Potomac.
• First production of all-iron edge rail, at Plymouth Ironworks, Merthyr Tydfil, South Wales.
• First introduction of a plateway, underground at Sheffield Park Colliery, Yorkshire, England, by John Curr.
• William Chapman designs a segmental skew arch at Finlay Bridge, Naas, on the Kildare Canal in Ireland.
• Levi Hutchins of New Hampshire produces a mechanical alarm clock.

Awards

• Copley Medal: John Hunter

Births

• January 24 – Christophe-Paulin de La Poix de Fréminville, French explorer and naturalist.
• March 6 – Joseph von Fraunhofer, Bavarian physicist.
• March 8 – Karl Ferdinand von Graefe, Polish-born German surgeon.
• March 9 – Josephine Kablick, Czech botanist and paleontologist.
• March 28 – Claudius James Rich, British archaeologist and anthropologist.
• March 29 – Carl Philipp Sprengel, German botanist.
• April 24 – Mathieu Orfila, Spanish-born French physician and chemist.
• May 27 – Benjamin Valz, French astronomer.
• June 2 – Nils Gabriel Sefström, Swedish chemist and mineralogist.
• June 3 – Auguste Le Prévost, French geologist, philologist, archaeologist and historian.
• June 4 – Constant Prévost, French geologist.
• June 7 – William Conybeare, English geologist.
• June 27 – Thomas Say, American naturalist.
• August 16 – Jean Michel Claude Richard, French botanist.
• August 24 – James Weddell, Flemish-born Anglo-Scots seal hunter and Antarctic explorer.
• September 5 – François Sulpice Beudant, French mineralogist et geologist.
• September 15 – Guillaume-Henri Dufour, Swiss engineer et topographer.
• November 5 – John Richardson, Scottish naturalist, explorer and surgeon.
• November 9 – Johann Natterer, Austrian naturalist.
• November 18 – Louis Daguerre, French inventor.
• December 17 – John Forbes, Scottish physician
• December 17 – Jan Evangelista Purkinje, Czech anatomist et neurophysiologist.
• Undated – Pierre Charles Alexandre Louis, French physician.

Deaths

• February 13 – Ruđer Bošković, Ragusan physicist, mathematician and astronomer
• May 10 – William Watson, English physician, botanist and physicist