Sources

1 "Unpublished letters of Dr Benjamin Franklin", July 1, 1783, through to December 15, 1783; December 16, 1783, through to June 30, 1784 and July 1, 1784, through to March 31, 1785. …
Chiswick April 17th 1784
Honoured Sir
I have received your two very kind letters of which the first was not dated and the last dated Passy March 26th. 1784 ... ... My dear sisters and brothers are in charming health except the last little one whose name was Sophia and who lately died of the Small-pox. ... … This is extracted from a letter Edward wrote to Dr Franklin addressed, "A Monsieur / Monsieur Le Docr. Franklin / Ministre plenipotentaire des / Etats unis d'Amerique / A Passy.