Complex sentence: De Gijselaar was a civil servant (pensionary) in Gorinchem, from 26 May 1776 until 1779, and from 1779 until 11 October 1787 he was pensionary of Dordrecht.
Split into simpler sentences: De Gijselaar was a civil servant (pensionary) in Gorinchem from 26 May 1776 until 1779. From 1779 until 11 October 1787 he was a pensionary of Dordrecht.