A much simpler method is the following. The sender and receiver of the communication must be agreed upon a certain book of a specified edition. The despatch begins with a number; this indicates the page to which the reader is to turn. He must then count the letters from the top of the page, and give them their value numerically according to the order in which they come; omitting those which are repeated. By these numbers he reads his despatch. As an example, let us take the beginning of this article: then, _I_ = 1, _n_ = 2, _w_ = 3, _h_ = 4, _e_ = 5, _m_ = 6, _d_ = 7, _l_ = 8, _o_ = 9, _u_ = 10, _v_ = 11, omitting to count the letters which are repeated. In the middle of the communication the page may be varied, and consequently the numerical significance of each letter altered. Even this could be read with a little trouble; and the word “impossible” can hardly be said to apply to the deciphering of cryptographs. A curious instance of this occurred at the close of the sixteenth century, when the Spaniards were endeavouring to establish relations between the scattered branches of their vast monarchy, which at that period embraced a large portion of Italy, the Low Countries, the Philippines, and enormous districts in the New World. They accordingly invented a cypher, which they varied from time to time, in order to disconcert those who might attempt to pry into the mysteries of their correspondence. The cypher, composed of fifty signs, was of great value to them through all the troubles of the “Ligue,” and the wars then desolating Europe. Some of their despatches having been intercepted, Henry IV. handed them over to a clever mathematician, Viete, with the request that he would find the clue. He did so, and was able also to follow it as it varied, and France profited for two years by his discovery. The court of Spain, disconcerted at this, accused Viete before the Roman court as a sorcerer and in league with the devil. This proceeding only gave rise to laughter and ridicule.