Philadelphia Pa. blue datestamp and matching "24" rate (Clarke 582) on cover to London, dated December 20, 1852. Illustrated cornercard for Reliance Line, Atkins & Co., depicting steam locomotive and railcars. Carried by Cunard Line’s Niagara departing Boston, with January 4, 1853 London arrival backstamp. Light wear, still a fine and and attractive transatlantic use of early railroad advertising.