Johann Heinrich Coert (Jan Hendrik / Johannes Henricus) was born in Westcappeln in 1761 and died in Pijnacker (Holland) on the 9th of August in 1801. He became a Surgeon in Pijnacker (he studied in Delft). In 1798 he received a Golden Medal from the ‘Maatschappij tot Redding van Drenkelingen’. On the 14th of October 1781 he married with Helena Sibilla Davidson in Pijnacker. Helena was born in Doesburg and died in Pijnacker on the 28th of October 1801. On the 1st of 4th of January 1758 she was Baptized in Doesburg. They had 7 children. Helena Elisabeth (born on the 15th of June 1784 in Pijnacker), Jan Hendrik (born on the 29th of November 1789 in Pijnacker; he moved arround 1806 from Rotterdam to Eastern Indonesia), Anna Maria (born on the 25th of February 1792 in Pijnacker; she died very young), Hendrik Jan, Frederik, Jacob Hendrik and Gijsbertus.