some other reason or purpose that he thus tried to divert the mind of the student from his earlier suggestion. It will probably be proved hereafter that more than one variant and reduction to lower dimensions of his biliteral cipher was used between himself and his friends. When the secrets of that "Scrivenry" which, according to Mr. W. G. Thorpe in his interesting volume, "The Hidden Lives of Shakespeare and Bacon," Bacon kept at work in Twickenham Park, are made known, we shall doubtless know more on the subject. Of one point, however, we may rest assured, that Bacon did not go back in his pursuance of an interesting study; and the change from "Quintuple at most" of the infolding writing of 1605, to "Quintuple at least," of 1623, was meant for some purpose of misleading or obscuration, rather than as a limitation of his original setting forth of the powers and possibilities of his great invention. It will some day be an interesting theme of speculation and study what use of his biliteral cipher had been made between 1605 and 1623; and what it was that he wished to conceal.
That the original cipher, as given, can be so reduced is manifest. Of the Quintuple biliteral there are thirty-two combinations. As in the Elizabethan alphabet, as Bacon himself points out, there were but twenty-four letters, certain possibilities of reduction at once unfold themselves, since at the very outset one entire fourth of the symbols are unused.
