just as the letter at the side is Transpositive of the second letter.  If the case occurs that a Position which is not found written in the direct order comes up for Transposition in the reverse order, then we must add to the letter of the General alphabet a point.  For example, if we have the word Mauritius to write, we must point the expression thus: G.zm.phmhkml.  For the rest, as respects the numbers written in the table, these will be attended to in the next Book.

Now just as in the first class, there were used three schemes, --the oblong, the circular and the square, -- so here, besides the oblong, the circular and the square table have their places.  The circular form is this:

What I said a moment ago about supplying the omitted Stations holds here.  The letters of the circumference, however, constitute the General Transpositive alphabet, and hence record the first of the two letters.  The wing, or movable index, contains the Particular alphabet, which, being composed throughout of two letters placed side by side, is written in such a way that the different letters squarely correspond with the eleven Positions of each column. The method of using should be this:  If the Station of the two letters given by the secret appears in its own form in the table, then the corresponding letter of the Former Order on the wing must be noted; if the Station is not expressed in its own form, but appears only from an inverted reading of the letters, the letter of the Latter Order performs the Transposition.

The square scheme is in this case as follows: