CH. XIV] CRYPTOGRAPHS AND CIPHERS 315 



slips we have to try, and had the above message been three 

 times as long, we could have solved the problem with half the 

 trouble. The above example was not complicated by employing 

 dummy letters or artificial alphabets: their use increases the 

 difficulty of the decipherer, but if the message is a long one, 

 the difficulties are not insuperable. Specialists, especially if 

 working in combination, are said to select the right methods 

 with almost uncanny quickness. 



This chapter has already run to such a length that I cannot 

 find space to describe more than one or two ciphers that appear 

 in history. 



It is said that Julius Caesar in making secret memoranda 

 was accustomed to move every letter four places forward, writing 

 d for a, e for b, &c. This would be a very easy instance of a 

 cipher of the first type, but it may have been effective at that 

 time. His nephew Augustus sometimes used a similar cipher, 

 in which each letter was moved forward one place *. 



Bacon proposed a cipher in which each letter was denoted 

 by a group of five letters consisting of A and B only. Since 

 there are 32 such groups, he had 6 symbols to spare, which 

 he could use to separate words or to which he could assign 

 special meanings. A message in this cipher would be five 

 times as long as the original message. This may be compared 

 with the far superior system of the five (or four) digit code- 

 book system in use at the present time. 



In the Morse code employed in telegraphy, as in the 

 Baconian system, only two signs are used, commonly a dot 

 or a short mark or a motion to the left, and a dash or a 

 long mark or a motion to the right. The Morse Alphabet is 

 as follows: «(•—), b ( ), c ( ), d ( ), e ( • ), 



/( ),g{ »(••••),»(■•),.?( ).*( )• 



l( ), m( ), n( — ),o( ),p( ),(?( ), 



»■(•—). «("■).*(-). «(■—). v ( )> w ( )• <"( )• 



* Of some of Caesar's correspondence, Suetonius says (cap. 56) si quis 

 investigare et persequi velit, quartam elementorum literam, id est, d pro «., et 

 perinde reliqvas commutet. And of Augustus he says (cap. 88) quoties autemper 

 notas scribit, b pro a, c pro b, ac deinceps eadem ratione, sequentes litera* ponit; 

 pro x autem duplex a. 



