3c Ultramarine (114).
Pair, tied by targets, "New Providence Ioa. Feb. 3" (1870) circular
datestamp on small cover to Dublin, Ireland, backstamped Montreal
(Feb. 8), red New York transit (Feb. 12), forwarded to Belfast with
Great Britain 1864 1p Red (33) tied by Dublin duplex datestamp and
diamond numeral grid, "H. & A. Pct. A Fe 24 3 1870" and Belfast (Feb. 25),
repaired tear at top clear of stamps, otherwise Fine, evidently sent by
Chicago exchange office to Montreal for an Allan Line sailing but
redirected to New York, illustrated in Rose book (p. 56) and Forster
article on mixed frankings (1982 Register, p. 93)
(Image) 
6c Ultramarine (115). Tied
by cork cancel, "Lewiston Me. May 13" (1870) circular datestamp on cover
to London, England, forwarded to Bagneres-de-Bigorre, France, and back
to London, an array of transit markings incl. scarce red "Portland
Me. Paid" exchange office datestamp and J. S. Morgan & Co. forwarder's
blue oval backstamp, forwarding postage to France paid by pair of Great
Britain 1865 4p Vermilion, Pl. 11 (43) tied by London duplex datestamp
and oval gridEXTREMELY FINE. A WELL-TRAVELLED COVER WITH A COLORFUL AND RARE COMBINATION OF UNITED STATES AND GREAT BRITAIN STAMPS TO PAY 6-CENT TREATY RATE AND 8-PENCE BRITISH RATE TO FRANCE.
Illustrated in Forster article on mixed frankings (1982 Register, p. 95). Ex Juhring. (Image)