Johan Sems

Biography

• In 1599, Sems became a silk merchant in Leeuwarden.
• 1600: The book Practijck des lantmetens, a book written by Sems and Jan Pietersz. Dou, was published. The book was used at the engineering school started by Simon Stevin.
• 1602: Sems was appointed land surveyor of Friesland.
• 1603: Sems made a detailed map of Leeuwarden, which was engraved by Pieter Bast.
• 1604-1608: Sems had the supervision over the building of the fortifications at Bourtange, Delfzijl and Bellingwolde.
• Sems bought several buildings in the city center of Leeuwarden.
• Around 1610 Sems moved to Bunde in Germany and he bought land in the Bunder Neuland, a polder that was created in 1604, with help from investors mainly from Amsterdam.
• 1615: Sems and Johan de la Haye determined the exact location of the border between Groningen and Drenthe, the Semslinie. They took the Martini tower as a reference point, but later measurements have shown that it would miss the Martini tower by 532 meters.
• 1616: From April 30 Sems was involved in land reclamation at Bredstedt. Later that year he designed the Christianshavn on Amager.
• 1618: On January 6, while he was in Denmark, Sems was asked to come to the Netherlands because of a border dispute between Groningen and Drenthe. at Ter Apel.
• 1621: Sems was back in Bunder Neuland. There were disputes between the Staten Generaal and Enno III, Count of East Frisia, about who had the rights in the polder.
• ca 1623: Sems was appointed dijkgraaf in the Bunder Neuland. In 1623 Jacob Matham produced an engraving of him, based on a portrait by Martin Faber.
• 1623: Sems lived in Groningen and his book De arithmetische fundamenten was published in Emden.
• 1625: The polder at Bredstedt was swept away by the sea during a storm.
• 1626: Sems was given the task to map the area north of Pieterburen.
• 1628: Sems got involved with the fortifications in eastern Groningen again.
• 1629 en 1632: Sems's 'movable possessions' were seized due to default of payment.
• 1634: Sems was in Dutch Brazil where he was involved as an engineer in the construction of fortifications at the conquered cities.
• 1635: Sems suddenly died in Groningen somewhere between January 1 and February 8. In 1636 his widow married the captain Jochum Bastijaen Coen.