Ferdinand I. (1793-1875) Emperor of Austria. Letter Signed as Emperor, 1p 12Â½x8`, Vienna, 8 Apr 1848. Very fine. To Ferdinand II, King of the Two Sicilies, congratulating him on the birth of a prince, with wishes that their houses be united in bonds of friendship, etc. With seven-word complimentary close in Latin. Original envelope has black wax seal.