al.

Suppose what you wish to communicate is as follows:

_I am so watched I cannot see you as I promised; but I will
meet you to-morrow in the park, with the letters, &c._

You begin with the letter _T_, and end with the letter _m_, which
shows how you have fixed the dial, and how your correspondent must fix
his, that he may decipher your letter.

Then, for _I am_, you write _b uf_, and so of the rest, as follows.

_T b uf lh pumrvayx b rvugghm lyy rhn ul b ikhfblyx vnm b
pbee fyym rhn mh-fhkkhp bg may iukd pbma may eymmykl, tw.
m._

_Another Way._

Take two pieces of card, pasteboard, or stiff paper, through which
you cut long squares at different distances. One of these you keep
yourself, and the other you give to your correspondent. You lay the
pasteboard on a paper, and, in the spaces cut out, write what you
would have understood by him only; then fill the intermediate spaces
with any words that will connect the whole together, and make a
different sense. When he receives it, he lays his pasteboard over
the whole, and those words which are between crotchets [ ] form the
intelligence you wish to communicate. For example: suppose you want
to express these word,

"_Don't trust Robert: I have found him a villain._"

"[Don't] fail to send my books. I [trust] they will be ready when
[Robert] calls on you. [I have] heard that you have [found] your dog.
I call [him a villain] who stole him." You may place a pasteboard of
this kind three other ways--the bottom at top--the top at bottom, or
by turning it over; but in this case you must previously apprize your
correspondent, or he may not be able to decipher your meaning.

_Secret Correspondence by Music._

Form a circle like Fig. 2, divided into twenty-six parts, with a
letter of the alphabet written in each. The interior of the circle is
moveable, like that in Fig. 1, and the circumference is to be ruled
like music-paper. Place in each division a note different in figure or
position.

[Illustration: Fig. 2.]

[Illustration: Music Piece]

Within the musical lines place the three keys, and on the outer circle
the figures to denote time. Then get a ruled paper, and place one of
the keys (suppose _ge-re-sol_) against the time 2-4ths, at the
beginning of the paper, which will inform your correspondent how to
place his circle. You then copy the notes that answer to the letters
of the words you intend to write, in the manner expressed