22 Hi neks on Secret Writing. 



nification of the symbols is varied, the other, in which it is per- 

 manent. In the former, the number of symbols is generally 

 small, and the cipherer depends for secrecy on the intricacy of 

 the law according to which their signification is changed, or on 

 the length of the period of the change. Under any circum- 

 stances this method is extremely troublesome ; but, if the law 

 of variation be not of the very simplest nature, the labour of 

 both the reader and the writer of the cipher will be prodigious ;• 

 and if the law be simple, it is plain that the period of the cipher 

 can contain no more loci, (as Mr. C. calls them,) than the cipher 

 contains characters ; and this, I think, insufficient (with the 

 usual number of characters, at least,) to defy the powers of a 

 decipherer. I consider, in fact, this kind of literal cipher so 

 obviously inferior to the other, that I should scarcely have 

 noticed it, but for the purpose of explaining Mr, C.'s first spe- 

 cimens, (Nos. 1 — 12,) in which he has employed it. 



The germ of this method is to be found in the dial-cipher of 

 the Encyclopaedia Britannica ; and, in fact, the key to these spe- 

 cimens may be most comtnodiously exhibited in the form of a 

 dial. Let there be constructed a circle of paste-board, move- 

 able on a pivot in its centre, and attached to a larger circle 

 concentric with it ; let the interval between the two peripheries, 

 and the rim of the inner pasteboard circle, be each divided into 

 thirty equal compartments, and in the former let the alphabet, 

 with Mr. C.'s four additional symbols, be arranged in the follow- 

 ing order ; viz., abcde4fghijk81mnopqrstiuvw 

 X y z ^ ; on the rim of the inner circle let the following letters 

 be arranged, viz., eeeaaiinnoossttrruubcdfghkl 

 m p y. Set the indicator, or capital letter prefixed to the 

 cipher, to correspond with the first of the three e's, and in this 

 position of the dial the signification of each letter in the outer 

 circle will be the corresponding letter in the inner circle. This 

 position of the dial will explain the first division of the cipher; 

 for the following division the inner circle must be moved for- 

 ward or backward, (as the position of Mr. C.'s arrow deter- 

 mines,) through one compartment ; and so for the other division; 

 always moving the inner circle a compartment forward or back- 



