1686 in science

	… 1676; 1677; 1678; 1679; 1680; 1681; 1682; ; 1683; 1684; 1685; 1686; 1687; 1688; 1689; ; 1690; 1691; 1692; 1693; 1694; 1695; 1696 …;
	Art; Archaeology; Architecture; Literature; Music; Philosophy; Science; +...

The year 1686 in science and technology involved some significant events.

Astronomy

John Ray begins publication of his Historia Plantarum, including the first biological definition of the term species;^[1] also his edition of Francis Willughby's Historia Piscum.^[2]

Edmund Halley establishes the relationship between barometric pressure and height above sea level.

Edmund Halley presents a systematic study of the trade winds and monsoons and identifies solar heating as the cause of atmospheric motions.^[3]

Isaac Newton uses a fixed length pendulum with weights of varying composition to test the weak equivalence principle to 1 part in 1000.

May 11 – Otto von Guericke, German physicist (born 1602)
November 25 (NS December 5) – Nicolas Steno, Danish pioneer geologist (born 1638)

^ Mayr, Ernst (1982). The Growth of Biological Thought: diversity, evolution, and inheritance. Cambridge, Massachusetts: Belknap Press. p. 256. ISBN 0-674-36445-7.
^ Egerton, Frank N. (October 2005). "A History of the Ecological Sciences, Part 18: John Ray and His Associates Francis Willughby and William Derham" (PDF). Bulletin of the Ecological Society of America. 86 (4): 301–313. doi:10.1890/0012-9623(2005)86[301:ahotes]2.0.co;2. Retrieved 2011-04-26.
^ Halley, E. (1686). "An Historical Account of the Trade Winds, and Monsoons, observable in the Seas between and near the Tropicks, with an attempt to assign the Physical cause of the said Winds". Philosophical Transactions of the Royal Society. 16. London: 153–168. doi:10.1098/rstl.1686.0026.
^ McConnell, Anita (2004). "Machin, John (bap. 1686?, died 1751)". Oxford Dictionary of National Biography. Oxford University Press. doi:10.1093/ref:odnb/17533. Retrieved 2007-06-26. (subscription or UK public library membership required)