it may also refer to a different type of cipher described by Fletcher Pratt in Secret and Urgent. It is "written by ruling a sheet of paper in vertical columns, with a letter at the head of each column. A dot is made for each letter of the message in the proper column, reading from top to bottom of the sheet. The letters at the head of the columns are then cut off, the ruling erased and the message of dots sent along to the recipient, who, knowing the width of the columns and the arrangement of the letters at the top, reconstitutes the diagram and reads what it has to say." See also Transposition cipher Scytale References Helen Fouché Gaines, Cryptanalysis, a study of ciphers and their solution, Dover, 1956, External links American Cryptogram Association Black Chamber page for encrypting and decrypting the Rail Fence cipher Classical ciphers