CRYPTOGBAPHY. 636 CRYSTALLOGBAPHY. cipher to the early ShaUespeare folios, iu which, as is generally known, more than one variety of type was used. The general principle involved in ttacon's method, that of representing the whole alphabet with groups and combinations of two symbols only, lies at the basis of many luodorn methods of signaling — the dot and dasli of llie ilorse telegraphic code, the right and left waving of flags in military or naval signal- ing, etc. In spite of the best that modern ingenuity can do to complicate cryptography, the art of deciphering cryptograms has well-nigh kept pace with it. Indeed, it is hardly too nuich to say that a code based upon any regular mathematical principle may be solved by ingenuity and pa- tience. If the language of the document is known in advance, the relative frequency with which the letters of the alphabet normally occur in that language forms an important initial clue. Thus e is the'letter of most frequent occurrence not only in our own language, but in French and German as well. In English the next in order of frequency are t, a, o, n, i, r, s, h, d, I, c, u u, m, etc. Single letters must be eiljier a, i, or o. Words of two letters most likely to occur are of, to, in, it, is, he, he, by, or, etc. Double letters are most apt to be ee, oo, ff. U, or s.5. If there is doubt whether the cipher is in Latin, English, French, or German, the lack of double letters at the end of words suggests that it is Latin; if but few words end with double letters, it is probably French : if they are very numerous, it is (ierman. A highly inflected language, like Latin, or even the Romance languages, with their com- plicated conjugations, must be easier to solve than English is, on account of the regular recurrence ot the same combinations of letters in the inflec- tional terminations. Those who make a science of interpreting cipher documents receive no small assistance from a knowledge of the frequency with which certain symmetrical combinations of letters occur in the vocabulary of a language. Thus, the combination which may be represented for convenience by the formula abab is compara- tively rare in English: one may cite papa, dodo: in French, tete, bibe. The form abeba is found in level; Fr., rever. In German, the formula abba gives only Anna, Ebbe, Egge, Esse, Otto; in French, the formula abcdabc gives only two words, cherche and quelque. Besides the writers on cryptography already mentioned, readers interested in the subject may be referred to John Baptist Porta, De Furtivis Liierarum Votis (1563); Blaise de Vigenfere, Traiti des chiffrcs (l.'JST) ; Thicknesse, A Treat- ise on the Art of Deciphering and of Writing in Cipher (1772) ; and am<]ng more modern writers, J. L. Kluber, Krgptographik (Tiibingen, 1809) ; Romani, La crypt ographie dfvoiUe (1875) ; and Fleissner. Eandhuch der Kryptographik (Vienna, 1881). CBYPTTJ'EI (Neo-Lat. nom. pi., from Gk. KpvTTbs, kryptos, hidden -f oipd., aura, tail). An order of birds, the tinamoxis. occupying a singular position and placed by Stejneger near the Apteryx and certain e.xtinet forms. They differ from all other Carinatoe (q.v.) in the character of the palate, which is like that of the ostrich. The order contains only a single family, which includes perhaps fifty species, all found only in South America. See Tinamou. CBYSTAL. See Cbystallograpiiy. CBYSTAL CLASS and CBYSTAL SYS- TEM. See Crtstalloghai'Uy. CBYS'TALLIN. See Gloislun. CRYSTALLINE LENS (Fr. cristallin, Lat. crystallinus, Gk. KpvuTaAlivbi:, kryslallinos, from Kpucr-aA2of, krystallos, crystal, from Kpmra- veiv, krystancin, to freeze, from KpOur, kryos, frost). A biconvex, transparent, solid body, situated immediately behind the pupil of the eye, and imbedded in the vitreous humor. Through it the rays of light from any object must pass to reach the retina. The crystal- line lens is more convex on its posterior than on the anterior surface, and its shape and consist- ency vary at dift'erent periods of life. In early youth it is nearly spherical and soft; as age ad- vances it becomes flattened and firm. In the adult human being it measures three-eighths of an inch transversely, and one-sixth of an inch in anteroposterior diameter-. The lens is re- tained in position by a capsule of equal trans- parency, composed of tissue exactly similar to ttie elastic layer of the cornea. The lens has no vascular connection with its capsule, but is nour- ished by means of a very delicate layer of nu- cleated cells on its surface, which absorb nourish- ment from the capsule. An increase in the refracting power of the eye for the purpose of near vision is called 'accommo- dation.' The mechanism of accommodation is a"s follows: The ciliarj- nuiscle contracts, drawing forward the choroid and ciliary processes and re- laxing the zonula. The lens, which had been flattened by the tension of the zonula, assumes, through its own elasticity, a more spherical shape. The posterior surface of the lens alters but little in shape, being fixed rather firmly in place ; but the anterior surface becomes more con- vex, and thus its refracting power is increased. The eye can see objects accurately at eveiy dis- tance between the 'far point' (the most distant ])oint of distinct vision for that eye) and the 'near point.' The 'near point' is situated at that place at which the eye can begin to see clearly the fine print on a page held close to the eye and then moved slowly from it. Between the 'near point' and the eye vision is indistinct, because the ciliary muscle cannot, by any efl'ort. produce the amount of convexity of the lens requisite for so short a distance. The term 'amplitude of ac- commodation' denotes the amount of accommoda- tive effort it makes in order to adapt itself from its 'far point' to its 'near point.' CBYSTALLINE ROCKS. A term used to include the igneous rocks (q.v.) and the meta- morphie rocks (q.v.), both of which classes have a more crystalline texture than that of the sedi- mentarv rocks. CRYSTALLINE SCHISTS. See Metamor- PHic Rocks. CEYSTALLOGENY, kris'tal-loj'e-nl. See Cbtstai,i.ogr.phy. CRYS'TALLOG'BAPHY (from Gk. xpi- araU-o^, krjjstallos, crystal -1- ypaoeiv, graphein, to write). The science which treats of crystals. A crystal is a portion of inorganic matter which has a definite molecular structure, and an out- ward form bounded by plane surfaces called crys- .tal faces. These faces are formed during the growth of the crystal, and have directions de- pendent upon the structure of the molecule of
