1690 in science

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The year 1690 in science and technology involved some significant events.

Astronomy

Giovanni Cassini observes differential rotation within Jupiter's atmosphere.
December – Earliest recorded sightings of the planet Uranus, by John Flamsteed, who mistakenly catalogues it as the star 34 Tauri.

French horticulturalist Jean-Baptiste de La Quintinie's Instruction pour les jardins fruitiers et potagers is published posthumously.

Izeki Tomotoki (井関知辰) of Osaka publishes Sampo-Hakki (算法発揮), in which he gives the resultant and the Laplace expansion of the determinant for the n×n case. At about this date, Tanaka Yoshizane (田中由真) also describes and applies the resultant, in Sampo-Funkai (算法紛解).
Michel Rolle publishes Traité d'Algebre, in which he gives the first published description in Europe of Gaussian elimination.

Justine Siegemund publishes Die Chur-Brandenburgische Hof-Wehemutter ("The Court Midwife"), the first medical textbook in German written by a woman.

February 3 – America's first paper money is printed in the Massachusetts Bay Colony.
A rudimentary working model of a liquid compass is introduced by Sir Edmond Halley at a meeting of the Royal Society.
French physicist Denis Papin, while in Leipzig and having observed the mechanical power of atmospheric pressure on his 'digester', builds a working model of a reciprocating steam engine for pumping water, the first of its kind, though not efficient.