1To Benjamin Franklin from Robert Morris, August 28[–September 7] 1781 (Franklin Papers)
...behind and lost one because of an accident: Dull, French Navy, pp. 243, 245, 370–1.
2To Benjamin Franklin from Robert Morris, 2 October 1783 (Franklin Papers)
Langdon had made an unsuccessful attempt to supply the French navy with masts in 1778: