Chapter XIII
On Oblique Transposition of Letters into Combinations
Of Fewer Letters: the Simpler Form thereof.

We have had Oblique Transposition into Letters (see c.6) and Oblique Transposition into consonants (c.11f), but into letters and consonants taken singly.  We come now to Oblique Transposition into certain combinations of fewer letters, or into letters joined together; in which case, however, never more than one secret letter is expressed by a single combination. This Mode taken as a whole is so accomplished that we may, by means of two, three, four , five, or seven letters, taken, not, as before, singly, but joined together and combined in various ways, express all the letters of the alphabet, and so write any and every secret.  Since, however, we may in this case too advance by three processes, -- by the systematic selection of one, two, or four letters, by the arbitrary choice of a single letter, or by the fortuitous collection of two or three letters, -- there arise three Modes of subdivision.  Of the first two of these I will treat in this chapter; of the third, in the following chapter.

The first Mode of subdivision, taking place by the selection of one or more letters combined in fixed order, varies on the basis of this order.  For, if four letters, as A,B,C, D, are selected, the order and arrangement shown by the following scheme must be adhered to:

Let the example be this, taken from Schwenter, P.221: Ba.b.bc*
d.b.ba* db.d.bb.bd.da.b.ac* bb.a* a.dd.d.ba* d.b.ba.d.ba* d.ba.db.d.ba*
da.c.ca.bb* da.c.aa* db.d.cd.bb* bb.b.d.ad.da.d.b.bb* ccc.c.bb.bb.d.ac*
ad.c.ac.d.b.ba*  cd.d.ac.bc.c.db.da.bb*  ad.c.bb*  cb.d.b.ba*  ca.cd.dc.aa*  ad.c.ac.d.b.ba* cb.a.bc*  ca.c.bb*  d.bb*  b.ba*  d.b.ba.d.ba*  aa.b.d.dc.d.ba*  dd.ac.cd.ba.ba.d.ba*  bb.a*  ccc.b.ac.ad.bb*  b.ba*  d.b.ba.d.ac*  bb.aa.cd.ba.ad.d.*  aaa.cd*  d.bbb.bb.bb*  c.cd.bd.da*  bc.b.aa.aa.d.ba*  b.bc*   bb.a.bc.bc.d.ac*

If we wish to write with three letters only, the following arrangeement, presented by de Vigenere, Traicte des Chiffres, p.200, is to be used, as is shown by the next to the last table in Bk 6.c.4.  From this table I will present only the first alphabet, which applies here, thus,

If you wish t write by means of this alphabet the sentence: Omnium rerum vicissitudo: the following form will be produced:  Bbaaccbbbabcbcbacc, babaabbabbcbacc, bcbabccababccbcabcbcabccaaabba.