[Illustration: Plate XXIV. FACSIMILES FROM PAGE 255 OF "GU TAVI SELENI CRYPTOMENYTICES," PUBLISHED 1624. [The Square Table is much enlarged].] This chapter describes how, by means of square tables, one letter followed by another letter will give the cypher letter. On the present page appears the square, which is shown in Plate 24, which enables us to answer the question "Quis quis." By means of this square we perceive that "a" followed by "e" gives us the letter F, that "I" followed by "o" gives us the letter R, and that "o" followed by "u" gives us the letter A. The answer therefore to Quis quis (which Bacon do you mean) is Fra [Bacon]. _See_ Plate 23, Page 107. [Illustration: Plate XXV. FACSIMILE FROM PAGE 2O2b OF "TRAICTE DES CHIFFRES OU SECRETES MANIERES D'ESCRIRE," PAR VlGENERE.] But what should induce us to look at this particular chapter on page 254 of the Cryptographic book for the solution? The answer is clearly given in the wonderful page 136 of the 1623 Folio of Shakespeare. As has been pointed out the numerical value of the long word Honorificabilitudinitatibus is 287, and the numerical value of Bacon is 33. We have found Bacon from Ba with a horn, and we require the remainder of his name, accordingly deduct 33 from 287, and we get the answer 254 which is the number of the required page in the Cryptographic book of 1624. But the wise Author knew that someone would say "How does this apply to the 1598 Quarto published twenty-six years before the great Cryptographic book appeared?" On Plate 24, Page 108, taken from page 255 of the Cryptographic book of 1624, it is shewn that the following lines are attached to the square "Quarta Tabula, ex Vigenerio, pag. 202.b, etc." =Square table taken from Vigenerio, page 202.b. This reference is to the work entitled, "Traicte des chiffres ou secretes manieres d'escrire": par Blaise de Vigenere, which was published in Paris in 1586. Spedding states (Vol. I. of "Bacon's Letters and Life," p. 6-8) that Francis Bacon went in 1576 to France, with Sir Amias Paulet, the English Ambassador. Bacon remained in France until 1578-9, and when in 1623 he published his "De Augmentis Scientiarum"--(the Advancement of Learning) he tells us that while in Paris he invented his own method of secret writing. _See_ Spedding's "Works of Bacon," Vol. 4, p. 445. The system which Bacon then invented is now known as the Biliteral Cypher, and it is in fact practically the same as that which is universally employed in Telegraphy under the name of the Morse Code. A copy of Vigenere's book will be found in the present writer's Baconian library, for he knew by the ornaments and by the other marks that Bacon must have had a hand in its production.