Chapter XXI
On Mixed Inverted Transposition:
By the Distinctive Apposition of Small Notes.

We come now to the third Mode obtained in the beginning of Chapter 19 by subdivision.  This takes place by the distinctive apposition of small notes, on the basis, once more, of a threefold division, according to the arrangement of the three tables given below.  Whence again arise three Special Modes.   These have this in common, that at the side there are found arranged three capital letters in each square;  also that each Mode contains, if not actually, at least by Power, four interior alphabets.  They differ in this, that the interior alphabet of the first Mode is itself composed of sixteen letters, -- whereby it happens that the anterior horizontal alphabet contains the like number of letters, -- not naturally, but artificially placed;  that the interior alphabet of the second Mode is composed of six letters;  and that the interior alphabet of the third Mode is composed of four letters only.  Whence it results that each letter of the interior alphabet represents by Power six letters in the third Mode, and in the second Mode five letters; and in the first Mode in like way it stands for three (4?) letters.  All this the tables, taken from de Vigenere, p. 246a, b, show more clearly.

Z  3