c.1807/8, if American; c.1809 if source is from the UK!
Citation: Report Together with Minutes of Evidence, and Accounts from the Select Committee Appointed to Investigate the High Price of Gold Bullion &c. (UK: 1810)
Germany (1807) : 1 Rthlr = Fl. 1.80
January 1807: 1 руб Banco = Fr. 2.70
mid-1807: 1 руб Banco = Fr. 2.176