enotes certain characters used in writing secret despatches, so that their contents shall be understood by none but those between whom the characters are agreed on.

The scytala of the Spartans has been regarded as a species of cipher. The scytala were two wooden cylinders exactly alike, one of which was kept by the ephori, the other by the general of the army sent on any expedition against the enemy. Whenever any secret orders were to be sent to the general, a narrow slip of parchment was wound close round the scytala, and on this the instructions were written. When taken off the cylinder only broken or single letters appeared; but their connection was at once restored by the general on applying the parchment to the scytala in his possession. Polybius says that Æneas Tacticus had collected together twenty different manners of writing, so as not to be understood by any but those in the secret; and that these methods were partly invented by himself, and partly in use before his time. Themistius, Baptista Porta, Vigenère, and P. Niceron, have written expressly on the subject of ciphers.

The art of writing in cipher has given rise to another art—that of deciphering or unravelling the meaning of such writing. The rules of deciphering are different in different languages. By observing the following, any one may read a common cipher written in English.

1. Observe the letters or characters that most frequently occur, and set them down for the six vowels, including y, and of these the most frequent will generally be e, and the least frequent u.

2. The vowels that most frequently come together are ea and ou.

3. The consonant most common at the end of words is s, and the next frequent is r or t.

4. When two similar characters come together, they are most likely to be the consonants f, l, or s, or the vowels e or o.

5. The letter that precedes or follows two similar characters is either a vowel, or l, m, n, or r.

6. In deciphering, begin with the words that consist of a single letter, which will be either, a, I, o, or s.

7. Then take the words of two letters, one of which will be a vowel. Of these words the most frequent are, an, to, be, by, of, on, or, no, so, as, at, if, in, is, it, he, me, my, us, see, am.

8. In words of three letters, there are most commonly two consonants. Of these words the most frequent are, the, and, not, but, yet, for, tho', how, why, all, you, she, his, her, our, who, may, can, did, was, are, has, had, let, one, two, six, ten, &c. Some of these, and words of two letters, will be found in every sentence.

9. The most common words of four letters are, this, that, then, thus, with, when, from, here, some, most, none, they, them, whom, mine, your, self, must, will, have, been, were, four, five, nine, &c.

10. The most usual words of five letters are, their, these, those, which, where, while, since, there, shall, might, could, would, ought, three, seven, eight, &c.

11. Words of two or more syllables frequently begin with double consonants, or with a preposition; that is, a vowel joined with one or more consonants. The most common double consonants are, bl, br, dr, fl, fr, gl, gr, ph, pl, pr, sh, sb, sp, st, th, tr, wh, wr, &c.; and the most common prepositions are, com, con, de, dis, ex, im, in, int, mis, per, pre, pro, re, sub, sup, un, &c.

12. The double consonants most frequent at the end of long words are, ch, ld, lf, mn, nd, ng, rl, rm, ra, rp, rt, sm, st, xt, &c.; and the most common terminations are, ed, en, er, es, et, ing, ly, son, sion, tion, able, ance, ent, ment, full, less, ness, &c.

By applying these rules, any common cipher written in English may be deciphered; and, mutatis mutandis, a cipher written in any language may be evolved by an application of the principle on which these rules are constructed.

CIPPUS, in Antiquity, a low column, with an inscription, erected on the high road or elsewhere, to show the way to travellers, to serve as a boundary, or to mark a grave. It was sometimes highly ornamented, as seen in the specimens in the British Museum.