In 1854, Sir Charles Wheatstone invented the cipher known as "Playfair," named ... include writing it by columns or writing it in a spiral starting at one corner and ending in the center.

Like the Playfair, the Double Playfair cipher uses 5x5 squares ... For keywords HAMBURG and NEWYORK written in rows and a spiral, respectively, we have the squares: H A M B U N L I/J H G R ...