James Boswell's uncle John was a member of a sect known as the Glasites.
Cornelius de Perponcher-Sedlnitzky
Cornelius de Perponcher-SedlnitzkyBorn May 03, 1733 at 's-Gravenhage
Died Oct 27, 1776 at Zuilen where he drowned
Son of Count Jacob Arent de Perponcher-Sedlnitzky and Jacoba Maria van Wassenaer. Married (1763) to Johanna Maria van Tuyll van Serooskerken, younger sister of Belle de Zuylen. He drowned in 1776.
He was a sometime justice in the supreme court of the province of Holland, and father of Hendrik George de Perponcher Sedlnitsky (1771-1856), a Dutch general and diplomat who commanded an army division at the battle of Waterloo (1815).
Boswell made a note to visit Perponcher on May 12, 1764. It is unclear whether they had met before this day.