1857 Wrapper Boston to Dublin with rare AMERCAN MAIL 1/-

1857 Part wrapper from New York to Dublin via Boston with superb BOSTON / B^R. PK^T in black, endorsed Per Mail Steamer "America" (which it missed), sent then by the "Africa" back via New York, arriving in Liverpool too late for immediate sorting and bagged direct to Dublin, receiving the rare "Open Horseshoe" AMERICAN MAIL / AP 13 / 1857 with superb handstruck 1/- below.
Ex Robertson and illustrated by him.