Jacobus Feenstra, born in Leeuwarden on July 13, 1856, son of Watze Jacob Feenstra (barge hand, bargeman and baker's man) and Anna Geertruida van Berkel, baker's man and sigarenwinkelier, living in Leeuwarden, died after June 24, 1910, aged at least 53 years.

Jacobus was married in Leeuwarden on August 12, 1882, at the age of 26 to
Tietje de Vries (aged 19 years), born in Leeuwarden on February 9, 1863, daughter of Thomas Douwes de Vries and Hiltje Jans de Groot, died there on June 24, 1910, aged 47 years.

• 1 : Watze Feenstra, born in Leeuwarden on January 11, 1883.
  Watze was married in Leeuwarden on February 26, 1908, at the age of 25 to Sjoukje Hemminga (aged 23 years), born in Leeuwarden on August 9, 1884, daughter of Sjouke Hemminga and Grietje Ablij.
  

• 2 : Thomas Jacobus Feenstra, born in Leeuwarden on December 27, 1893.