1868 (Mar. 14) Liverpool, England to Boston, Mass., folded letter with Liverpool (3.14) origin backstamp, carried by Cunard Line China from Liverpool Mar. 14 to Boston arriving Mar. 26, "Boston Br. Pkt. Mar 27" exchange backstamp and matching unlisted "In U.S. Notes 37" depreciated currency marking, Very Fine. Estimate  $300 - 400. Letter posted in Liverpool Packet Letter Office (circular datestamp on reverse). Letter was a double rate letter and required 2x12¢ (the new treaty rate) = 24¢ postage due if paid in coin or 37¢ in depreciated greenback notes. The latter included a 5¢ unpaid letter fine in addition to the premium for the depreciated currency. Boston used a 24mm. circular IN U.S. NOTES marking to indicate the notes fee only. $0 (Image)