APPENDIX A
"In the First Edition of his work "The Two Bookes of Francis Bacon, of the proficience and advancement of Learning, divine and humane" published at London in 1605, the Author only alludes briefly to his Bi-literal Cipher. Speaking of Ciphers generally (Booke II) he says:
"But the vertues of them, whereby they are to be preferred, are three; that they be not laborious to write and reade; that they bee impossible to discypher; and in some cases, that they bee without suspicion. The highest Degree whereof, is to write OMNIA PER OMNIA; which is undoubtedly possible, with a proportion Quintuple at most, of the writing infoulding, to the writing infoulded, and no other restrainte whatsoever."
It was not till eighteen years later that he gave to the public an explanation of this 'infoulding' writing. In the rarely beautiful edition of the work in Latin printed in London by Haviland in 1623, the passage relating to secret writing is much amplified. Indeed the entire work is completed in many ways and greatly enlarged as is shown by its title.
"De Dignitate et Augmentis Scientiarum. Libros IX."
The following is his revised statement:
"Ut vero suspicio omnis absit, aliud Juventum subijciemus, quod certe, cum Adolescentuli essemus Parisiis, excogitavimus; nee etiam adhuc visa vobis res digna est, quae pereat. Habet enim gradum Ciphrae altissimum; nimirum ut Omnia per Omnia significari possint: ita tamen, ut Scriptis quae involuitut, quintuplo minor sit, quam ea cui involvatur: Alia nulla omnino requiritur Conditio, aut Restrictio. Id hoc modo fiet. Primo, universae literae Alphabeti in duas tantummodo Literas soluantur, per Transpositionem earum. Nam Transpositis duarum Literarum, per Locos quinque, Differentiis triginta duabus, multo magis viginti quatuor (qui est Numerus Alphabeti apud nos) sufficiet. Huius Alphabeti. Exemplum tale est."

"But for avoiding suspicion altogether, I will add another contrivance, which I devised myself when I was at Paris in my early youth, and which I still think worthy of preservation. For it has the perfection of a cipher, which is to make anything signifying anything; subject however to this condition, that the infolding writing shall contain at least five times as many letters as the writing infolded; no other condition or restriction is required. The way to do it is this: First let all the letters of the Alphabet be resolved into transpositions of two letters only. For the transposition of two letters through five places will yield thirty-two differences; much more twenty-four, which is the number of letters in our Alphabet. Here is an example of such an Alphabet.

A
B
C
D
E
F
G
H

aaaaa
aaaab
aaaba
aaabb
aabaa
aabab
aabba
aabbb

I
K
L
M
N
O
P
Q

abaaa
abaab
ababa
ababb
abbaa
abbab
abbba
abbbb

R
S
T
V
W
X
Y
Z

baaaa
baaab
baaba
baabb
babaa
babab
babba
babbb

"Nor is it a slight thing which is thus by the way effected. For heare we see how thoughts may be communicated at any distance of place by means of any objects perceptible either to the eye or ear, provided only that those objects are capable of two differences; as by bells, trumpets, torches, gunshots, and the like. But to proceed with our business. When you prepare to write, you must reduce the interior epistle to this bi-literal alphabet. Let the interior epistle be:

Fly.

Example of reduction.

F
L
Y

aabab
ababa
babba

"Have by you at the same time another alphabet in two forms; I mean in which each of the letters of the common alphabet, both capitals and small, are exhibited in two different forms,—any forms that you find convenient."
[For instance, Roman and Italic letters; "a" representing Roman and "b" representing Italic.]
"Then take your interior epistle, reduced to the bi-literal shape, and adapt it, letter by letter, to your exterior epistle in the biform character; and then write it out. Let the exterior epistle be.

"Do not go till I come."

Example of reduction

F
L
Y

aabab
ababa
babba

DONOT
GOTIL
LICOM—E

do not
go till
I come

From the above given dates it would almost seem as if Bacon had treated the matter in a purely academic manner, and had drawn out of his remembrance of his younger days a method of secret communication which had not seen any practical service. Spedding mentions in his book "Francis Bacon and his Times" that Bacon may have got the hint of the 'bi-literal cypher' from the work of John Baptist Porta, "De occultis literarum notis," reprinted in Strasburg in 1606, but the first edition of which was published when Porta was a young man. It is however manifest from certain evidence, that Bacon practised his special cipher and used it for many years. Lady Bacon, mother of the philosopher, writing in 1593, to her son Anthony, elder brother of Francis, speaking of him, Francis, says, "I do not understand his enigmatical folded writing." Indeed it is possible that many years before he had tried to have his invention made use of for public service. His was an age of secret writing. Every Ambassador had to send his despatches in cipher, for thus—and even then not always—could they be safe from hostile eyes. The thousands of pages of reports to King Philip made by Don Bernardino de Mendoza, the Spanish Ambassador at the Court of Queen Elizabeth, before the time of the Armada, were all written in this form; the groaning shelves of the records at Simancas bear evidence of the industry of such political officials and of their spies and secretaries. An ambitious youth like Francis Bacon, son of the Lord Keeper, and so traditionally and familiarly in touch with Court and Council, who in his baby days was addressed by Elizabeth as her "young Lord Keeper," and who spent the time between his sixteenth and eighteenth years in the suite of the English Ambassador in Paris, Sir Amyas Paulet, must have had constant experience of the need of a cipher which would fulfill the conditions which he laid down as essential in 1605—facility of execution, impossibility of discovery, and lack of suspiciousness. When, in a letter of 16 Sept. 1580, to his uncle Lord Burghley, he made suit to the Queen for some special employment, it is possible that the post he sought was that of secret writer to Her Majesty. His letter, though followed up with a more pressing one on 18th October of the same year, remained unanswered. Whatever the motive or purpose of these last two letters may have been, it remained on his mind; for eleven years later we find him again writing to his uncle the Lord Keeper: "I ever have a mind to serve Her Majesty," and again, "the meanness of my estate doth somewhat move me." In the interval, on 25th August, 1585, he wrote to the Right Hon. Sir Francis Walsingham, Principal Secretary to the Queen: "In default of getting it, will go back to course of practice (at Bar) I must and will follow, not for my necessity of estate but for my credit's sake, which I fear by being out of action will wear." His brother Anthony spent the best part of his life abroad, presumably on some secret missions; and as Francis was the recipient of his letters it was doubtless that "folded writing" which so puzzled their mother which was used for the safety and secrecy of their correspondence. Indeed to what a fine point the biliteral method must have been brought by Bacon and his correspondents is shown by the extraordinarily minute differences given in his own setting forth of the symbols for "a" and "b" etc., in the "De Augmentis" of 1623 and later. In the edition printed in Latin in Paris the next year, 1624, by Peter Mettayer, the differences, possibly through some imperfection of printing, are so minute that even the reader studying the characters set before him, with the extra elucidation of their being placed under their proper headings, finds it almost impossible to understand them. The cutting for instance of the "n" which represents "a" and that which represents "b" seems, even after prolonged study, to be the same.
It is to be noticed that Bacon in setting forth the cipher in its completeness directs attention to its infinite possibilities and variations. The organised repetition of any two symbols in combinations of not more than five for one or both symbols may convey ideas. Not letters only but colours, bells, cannon, or other sounds may be used with effect. All the senses may be employed, or any or some of them, in endless combinations.

 Again it is to be noted that even in his first allusion to the system in 1605, he says, "to write Omnia per Omnia, which is undoubtedly possible, with a proportion Quintuple at most, of the writing infoulding, to the writing infoulded."
"Quintuple at most!" But in the instances of his system which he gives eighteen years later, when probably his time for secret writing as a matter of business had ceased, and when from the lofty altitude of the Woolsack he could behold unmoved any who had concealments to make—provided of course that they were not connected with bribes—there is only one method given, that of five infolding letters for each one infolded. In the later and fuller period he speaks also of the one necessary condition "that the infoulding writing shall contain at least five times as many letters as the writing infoulded"—
Even in the example which he gives "Do not go till I come," there is a superfluous letter, the final "e;" as though he wished to mislead the reader by inference as well as by direct statement.
Is it possible that he stopped short in his completion of this marvellous cipher? Can we believe that he who openly spoke from the first of symbols "quintuple at most," was content to use so large a number of infolding letters when he could possibly do with less? Why, the last condition of excellence in a cipher which he himself laid down, namely, that it should "bee without suspicion," would be endangered by a larger number than was actually necessary. It is by repetition of symbols that the discovery of secret writing is made; and in a cipher where, manifestly, the eye or the ear or the touch or the taste must be guided by such, and so marked and prolonged, symbols, the chances of discovery are enormously increased. Doubtless, then, he did not rest in his investigation and invention until he had brought his cipher to its least dimensions; and it was for 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.