cover 12c Black (17), three singles, just clear to large margins, one has light toning, used with 1c Blue type IV (9), large margins to barely in, tied by "Philadelphia Pa. Apr 15" c.d.s. cancels on 1856 blue folded letter to Alexandroffsky, "near St. Peterburg", Russia, red boxed "Aachen 20/Franco" h.s., ms. "via Prussian Closed Mail", magenta ms. "14" credit (to Germany) on front, red "New-York Br. Pkt. Apr 16" exchange h.s. on reverse, carried by Cunard Line's Asia, this cover paid the 37c rate to Russian via Prussian Closed Mail, trifle heavy vertical cover file fold, otherwise very fine, one of only three known 1851 Issue covers used to Russia, a scarce and very desirable cover worthy of the very finest collection photo