black datestamp on cover to St. Petersburg, Russia, franked with 1857 1c Blue and 12c Black right margin horizontal strip of three (24, 36) with magenta grid cancels, crayon "14" credit to Prussia, backstamped "Boston Br. Pkt. Jul 14", carried aboard Cunard's Arabia arriving Liverpool July 24, red boxed "Aachen 27 7 Franco" transit, Russian arrival backstamp, center 12c a few scissor-blunted perforations at top, very fine cover paying the 37c rate via Prussian Closed Mail, 2020 Philatelic Foundation certificate