Editing 1690 (section)

=== Date unknown ===
* [[Serbian Patriarch]] [[Arsenije III Carnojevic]] leads the first of the two [[Great Serbian Migrations]] into the [[Habsburg monarchy|Habsburg Empire]], following [[Ottoman Empire|Ottoman]] atrocities in [[Kosovo]].
* The [[Hearth#Hearth tax|Hearth Tax]] is abolished in [[Kingdom of Scotland|Scotland]], one year after its abolition in England and [[Wales]].
* 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 engine|reciprocating]] [[steam engine]] for pumping water, the first of its kind, though not efficient.
* Dutch [[polymath]] [[Christiaan Huygens]] publishes his book ''[[Treatise on Light]]''. The book is considered a pioneering work of theoretical and mathematical physics.
* [[Giovanni Domenico Cassini]] observes [[differential rotation]] within [[Jupiter]]'s atmosphere.
* The construction of [[Fort Longueuil]], a stone [[fort]] in [[Longueuil]], in [[Quebec]], [[Canada (New France)|Canada]], is completed. It is one of the only buildings in Canada that could ever be considered a castle (fortified residence for a noble), and out of those buildings it most resembles the castles of Europe.
* The [[Barrage Vauban]], a defensive work in the city of [[Strasbourg]] (in modern-day [[France]]), is completed.<ref>{{cite book|author=Yves Barde|title=Vauban: ingénieur et homme de guerre|url=https://books.google.com/books?id=j0sjAQAAIAAJ|year=2006|publisher=Éd. de l'Armançon|isbn=978-2-84479-085-9|page=91|language=fr}}</ref>
* The French dictionary and encyclopaedia ''Dictionnaire universel, contenant generalement tous les mots françois'', compiled by [[Antoine Furetière]], is published posthumously.
* Possible year of the disappearance of the western part of the island of [[Buise]], in [[St. Peter's Flood]].</onlyinclude>