1864 (May 4) New York, N.Y. to Paris, France, folded letter at the unpaid 15¢ French Mail treaty rate with black "New York '6' May 4" debit cds, carried on Cunard Line Australasian from New York May 4 to Queenstown arriving May 14, red Calais (5.17) entry cds and "16" decimes due rating, forwarded to London with "British [4] / Foreign [1/4]" (Talbeart B3, Willcocks-Jay 1071), various backstamps including London (5.20) arrival cds, Very Fine, a rare usage on transatlantic mail. Estimate  $400 - 600. $0 (Image)