UNITED STATES - France. 1856 cover from Philadelphia, carried to the mails by Blood"s Penny Post, and franked by their 1 cent bronze on lilac label (Sc 15L14). Stamp tied by acid stain, plus "30" cent rate marking applied by the Philadelphia exchange office in anticipation of Prussian Closed Mail service. Front shows BLOOD"S / DESPATCH c.d.s., PHILADELPHIA / PA c.d.s., plus black N. YORK BR. PKT. c.d.s. with integral "23" cent debit (subsequently struck out when New York elected to send this letter in the British Open Mails). The British applied the GB / 1F60c accountancy marking, and "16" decimes was collected upon delivery in France. A rare use of a U.S. local stamp on a foreign destination item, and the only recorded example on a "three month" cover sent just prior the the 1857 US-French Convention. Scott 15L14. (Photo). Est. 2 000 - 3 000 CHF.