India: The Topaz Cancellation Collection & India Used abroad

ADEN
1879 (Nov 6) Envelope from Aden to the USA with 1866-78 4a green and 1876 6a olive-bistre paying the double letter rate tied by "B-22" squared barred numeral with Aden cds adjacent, reverse with London and Philadelphia bs, small central tear at top of cover, fine and scarce, covers to the US are particularly scarce at this early period as are examples of this rate
This cover was dispatched from a member of the crew of the U.S.S. Ticonderoga on a mission to Africa, the Middle-East, and Asia in 1878-1880 to further open American trade in this part of the world