Graaf Mr. Jan Henry van Heemskerck
       Heer van Achttienhoven 
       Born 14 September 1739 
       Died 1808 
       Married (1) 13 March 1763 Haarlem 
       Geertruyt Catharina Testart, daughter of Elbert Testart and 
       Anna Margaretha Fannius 
       Born 4 December 1741 Haarlem 
       Died 27 September 1775 in Surinam 
       Married (2) 27 April 1778 
       Johanna Susanna Danderen 
                 Children, Generation I 

       Generation I 
        (1) 1  Gravin Jacoba Susanna van Heemskerck 
               Born 24 February 1768 Haarlem 
               Died 18 February 1812 Amsterdam 
               Married 13 November 1791 Haarlem 
               Jhr. Leonard Rutgers van Rozenburg, Regent in Amsterdam 
               1787, son of Leonard Rutgers van Rozenburg and Eleonora 
               Ang‚lique Louise Tronchin du Breuil 
               Born 16 February 1760 
               Died 6 August 1831 

            2  Gravin Agnes Margaretha van Heemskerck 
               Born 4 May 1769 Haarlem 
               Died 19 August 1845 H.Stadwijk, nr Haarlem 
               Married 8 May 1792 Nantes 
               Jhr. Mr. Louis Rutgers van Rozenburg, son of Leonard 
               Rutgers van Rozenburg and Eleonora Ang‚lique Louise 
               Tronchin du Breuil 
               Born 24 June 1763 Amsterdam 
               Died 30 March 1839 Amsterdam 

                                   Source Listing
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           De vroedschap van Amsterdam 1578-1795, 
           two volumes 
                                     by Johan E. Elias