296 



CRYPTOGRAPHS AND CIPHERS 



[CH. XIV 



and then the communication can be read by reading the columns 

 downwards. For instance, if the following communication, 

 containing 270 letters, were received: Ahtze ipqhg esoae ouazs 

 esewa eqtmu sfdtb enzce sjteo ttqiz yczht zjioa rhqet tjr/e sftnz 

 mroom ohyea rziaq neorn breot lennk aerwi zesju asjod ezwjz 

 zszjb rritt jnfjl weuzr oqyfo htqay eizsl eopji dihal oalhp epkrh 

 eanaz srvli imosi adygt pekij scerq vvjqj qajqn yjint kaehs bhsnb 

 goaot qetqe uuesa yqurn tpebq stzam ztqrj, and the clue number 

 were 17 we should put 16 letters in each of the first 15 lines 

 and 15 letters in each of the last 2 lines. The communication 

 could then be discovered by reading the columns downwards : 

 the letters j, q and z marking the ends of words. 



A better cryptograph of this kind may be made by arranging 

 the letters cyclically, and agreeing that the communication is to 

 be made by selected letters, as, for instance, every seventh, second, 

 seventh, second, and so on. Thus if the communication were 

 Ammunition too low to allow of a sortie, which consists of 32 

 letters, the successive significant letters would come in the 

 order 7, 9, 16, 18, 25, 27, 2, 4, 13, 15, 24, 28, 5, 8, 20, 22, 1, 6, 

 21, 26, 11, 14, 32, 10, 31, 12, 17, 23, 3, 29, 30, 19— the numbers 

 being selected as in the decimation problem given above at 

 the end of chapter I, and being struck out from the 32 cycle as 

 soon as they are determined. The above communication would 

 then read Ttrio oalmo laoon msueo awotn lioti fw. This is a 

 good method, but it is troublesome to use, and for that reason 

 is not to be recommended. 



In another cryptograph of this type, known as the Route 

 Method, the words are left unaltered, but are re-arranged in a 



pre-determ-ined manner. Thus, to take a very simple example, 

 the words might be written in tabular form in the order shown 



