Johann Ludwig Tiarks (10 May 1789 – 1 May 1837) was a German mathematician and astronomer who was involved in determining the boundary between the United States and British North America.
[1] At the end of July 1818 Tiarks and his group left Akwesasne and with the American surveying team headed to Lake Champlain.
[1] At the lake both teams independently discovered that John Collins and others had incorrectly located the 45th parallel north, placing the fort at Rouses Point, New York in British territory.
[1] During summer 1820 he was working in what became northwestern New Brunswick and nearby areas of Quebec, returning to the upper Connecticut that fall.
[1] He returned to North America in 1825 to determine the most northwesterly point of the Lake of the Woods, from which the boundary was supposed to run due west to the Mississippi River.
[1] He was called to The Hague to explain certain points to William II of the Netherlands, who had been asked to arbitrate the boundary question.