554 



CRY PTOG RAPH Y CRYSTALS. 



ing several very numerous families of plants, in whir 

 the parts essential to their fructification have not bee 

 sufficiently ascertained, or are too small to admit < 

 their being accurately described ami referred to an 

 of the oilier dart's. 



CRYPTOGJIAPHY (from the Greek e i/-ri, se- 

 crci, and yjfu, to write) ; the art of transmitting 

 weret information by means of writing, which is in 

 tended to be illegible, except by the person for \vhon 

 it is destined. The ancients sometimes shaved 1 1 

 head of a slave, and wrote upon the skin with sonu 

 indelible colouring matter, and then sent him, after 

 his hair had grown again, to the place of his destina- 

 tion. TJjis is not, however, properly secret writing 

 out only a concealment of writing. Another sort 

 which corresponds better with the name, is the fol- 

 lowing, used by the ancients. They took a smal 

 stick, and wound around it hark, or papyrus, upon 

 which they wrote. The bark was then unrolled, ane 

 sent to the correspondent, who was furnished with a 

 stick of the same size. He wound the bark again 

 round this, and thus was enabled to read what had 

 been written. Tliis mode of concealment is evident- 

 ly very imperfect. Among the methods which Ovid 

 teaches young women, in order to deceive their 

 guardians, when they write to their lovers, he men- 

 tions that of writing with new milk, and of making 

 the writing legible by means of coal dust or soot. 

 Ansonius proposes the same means to Paulinus. It 

 is now well known that several metallic solutions 

 may be employed for this purpose ; and that these, 

 on being exposed to the action of certain vapours, 

 become visible, and thus exhibit the characters which 

 had been written with them. 



Cryptography properly consists in writing with 

 signs, which are legible only to him for whom the 

 writing is intended, or who lias a key, or expla- 

 nation of the signs. The most simple method 

 is to choose for every letter of the alphabet some 

 sign, or only another letter. But this sort of cryp- 

 tography (chiffre) is also easy to be deciphered with- 

 out a key. Hence many illusions are used. No se- 

 paration is made between the words, or signs of no 

 meaning are inserted among those of real meaning. 

 Various keys likewise are used, according to rules 

 before agreed upon. By this means, the deciphering 

 of the writing becomes difficult for a third person, 

 not initiated ; but it is likewise extremely trouble- 

 some for the correspondents themselves ; and a slight 

 mistake often makes it illegible, even by them. An- 

 other mode of communicating intelligence secretly, 

 viz., to agree upon some printed book, and mark the 

 words out, is also troublesome, and not at all safe. 

 The method of concealing the words which are to 

 convey the information intended in matter of a very 

 different character, in a long letter, which the corres- 

 pondent is enabled to read, by applying a paper to it, 

 with holes corresponding to the places of the signifi- 

 cant words, is attended with many disadvantages : 

 the paper may be lost; the repetition of certain words 

 may lead to discovery; and the difficulty of connect- 

 ing the important with the unimportant matter, so as 

 to give the whole the appearance of an ordinary let- 

 ter, is considerable. If this is effected, however, this 

 mode has the advantage of concealing the feet that 

 any secrecy is intended. Writing with sympathetic 

 ink, or milk, lemon-juice, &c., is unsafe, because the 

 agents to make the letters visible are too generally 

 known. Hence the chiffre quarre, or chiffre inde- 

 chiffrable, so called, has come very much into use, 

 because it is easily applied, difficult to be deciphered, 

 and the key may be preserved in the memory merely, 

 and easily changed. It consists of a table, hi which 

 the letters of the alphabet, or any other signs agreed 

 ujn are arranged under one another, thus : 



Any word is now taken for a key ; Paris, for exam- 

 ple. This is a short word, and, for the sake of se- 

 crecy, it would be well to choose for the key some 

 one or more words less striking. Suppose we wish 

 to write in tliis cipher, with tliis key, the plirase 

 " We lost a battle ;" we must write Paris over the 

 plirase, repeating it as often as is necessary, thus :- 

 f a rif P ar i s Pa r 

 Welostabattle. 

 We now take, as a cipher for w, the letter which we 

 ind in the square opposite w in the left marginal co- 

 umn, and under on the top, which is m. Instead 

 of e, we take the letter opposite e and under a, which 

 is /; for /, the letter opposite / and under r, and so 

 on. Proceeding thus, we should obtain the following 

 series of letters : 



mfcxlibtkmimw 

 The person who receives the epistle writes the key 

 over the letters ; as, 



P ar i s Pa r i 3 P a r 



mfcxlibtkmimw 

 le now goes down in the perpendicular line, at the 

 p of which is p, until he meets m, opposite to which, 

 n the left marginal column, he finds w. Next, go- 

 ing in the line of a down to/, lie finds on the left e. 

 "n the same way, r gives /, i gives o, and so on. Or 

 rou may reverse the process ; begin with p, in the 

 eft marginal column, and look along horizontally till 

 ou find m, over which, in the top line, you will find 

 o. It is easily seen, that the same letter is not al- 

 ways designated by the same cipher ; thus, e and 

 >ccur twice in the phrase selected, and they are de- 

 ignated respectively by the ciphers /and w, b and 

 ;. The key may be clianged from time to time, 

 and a different key may be used with each correspon- 

 lent. The utmost accuracy is necessary, because one 

 :lmracter, accidentally omitted, clianges the whole 

 :ipher. The correspondent, however, may ascertain 

 his with considerable trouble. See Deciphering. 



CRYSTALS, in chemistry and mineralogy ; any 

 norganic body, which, by the mutual attraction of its 

 jarticles has assumed the form of some one of the 

 egular geometric solids, being bounded by a certain 

 lumber of plain surfaces. The chemist procures 

 rystals, either by fusing the bodies by heat, and 

 hen allowing them gradually to cool, or by dissolving 

 tiem in a fluid, and then abstracting the fluid by 

 low evaporation. The nature of crystals has, from 

 ts great importance, been a subject of investigation 

 o many eminent men ; but, more particularly to 

 ome de 1'Isle, Bergman, and U. R. J. Hany. This 

 ast philosopher, from an observ ation of the well known 

 ict, that crystals can be divided only in certain 

 irections, so that the fraction may have a smooth 



