Copenhagen 19 September 1851 to St. Croix, Danish West Indies. Royal Service letter to the Governor of Danish West Indies at St. Croix, stamped with boxed 'Aus Daenemarck. / d. Meckleburg', tpo 'HAGENOW-ROSTOCK', 'MAGDEBURG-WITTENBERG', 'BERLIN-HAMBURG', 'BERLIN-MINDEN' and 'AACHEN - BAHNHOF 22/9' and red 1-ring London 'AN 23SP23 1851'. An unusal Royal Service letter to Danish West Indies, effected by the tropical climate.