|Parchment mentioning Gaspar Weiss,|
C12/110/18, National Archive UK, dated Nov 1777.
Died: late April 1778, London
Father: Jean Gaspard Weiss, 1739-1815
Mother: Marie Baumgarten, 1755-1798
Gaspar Weiss was baptised on 12 October 1777 at St Marylebone, Westminster, one month after his birth.
Some legal records held in the UK National Archives mention Gaspar - there were a series of lawsuits brought by Gaspar's maternal grandfather Samuel Baumgarten over a number of years, disputing the distribution of inheritances within the Joynes family (Samuel Baumgarten's in-laws) names Gaspar as Gaspar Weiss the Younger. By June 1783, lawsuit documents no longer mention him amongst the children of Gaspard and Marie Weiss, from which we must conclude that he was no longer alive.
In fact Gaspar Weiss died in late April 1778 - his burial service was held at St Marylebone on 27 April 1778, his name was written in the burial register as Casper Weiss, and the entry notes he was a child.
There has in the past been a suggestion that Gaspar Weiss was in partnership with his brother Willoughby in a music selling business in Liverpool, but this is clearly not possible - further research may be able to ascertain who this particular Gaspar Weiss was. Moore (undated) mentioned a set of preludes and solos, published in Milan by Ricordi (circa 1820) that he attributed to Gaspar Weiss - we know now that this also is not possible. Tobias Bonz instead attributes the work in question to Gaspar's father, Gaspard Weiss, apparently published after his death.