A New or Improved Cryptograph.
Year: 1894

page_text: Date of Application, 12th Nov., 1894-Accepted, 12th Jan.. 1895
A New or Improved Cryptograph.
A communication by GEORG STRÖMDAL, of Nedre Slotsgade 3, and JOHANNES
VON DITTEN, of Drammensveien 64 B, both in Christiania, in the Kingdom
of Norway, Artists.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 6, Lord Street Liverpool and 6 Bank Street,
Manchester both in the County of Lancaster and 31 High Holborn in the County
of Middlesex, Civil Engineer, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
This invention relates to apparatus to be used as a key for cryptographic letters
and has for its object to provide simple means for bringing the letters, constituting
the alphabets, out of order so as to make it impossible for anyone to place the
alphabets so that the instrument may be used to decipher a certain letter.
Figure 1 in annexed drawing shows a plan view of the instrument in question,
Figure 2 shows a perspective view of the same opened,
Figure 3 shows the cryptograph in the hand of a person, as it is held when used.
The case A is provided with a cover B having a circular opening C. Around
this opening is arranged on the outside of the cover one alphabet D, the letters of
which may be impressed in the material of the cover; another alphabet E is placed
inside the case on a disc which is rotatable on the pin H. On the periphery of
this disc are as many teeth as there are letters in the alphabet. These letters may
be printed or otherwise marked on small pieces G, which are loose and are held on
their place by means of the lips F of the teeth on the disc. Between the said
rotatable alphabet disc and the hinged lid of the case is placed a lever I which is
pivotted at K and has two teeth M and L one on each side of the pivot. A
spring N keeps the tooth M in engagement with the teeth of the wheel and the
tooth L may be brought in such engagement by pressing on the end of the lever
reaching outside the casing through a hole in the same. By such a pressing the
tooth L pushes the wheel round a little less than the length of a tooth and when
the lever works back again the tooth M pushes the wheel the rest of the length of
a tooth and locks the wheel.
66
The apparatus may be used in different ways, which will be understood by anyone
familiar with cryptographic instruments. The object of making the letters of the
inner alphabet loose is to enable the writer and reader of the cryptogram to arrange
the letters in a certain: predetermined order; such for instance as shown in the
drawing where the letters are intermixed in the following manner so as to form
the keyword hydrogenium. The letters are first arranged alphabetically.
H" (the first letter of the keyword) is then taken up and placed in the position
of "A," the latter being carried to the position vacated by "H"; "Y" (the next
letter of the keyword) is then taken up and placed next to "H" in place of "B,"
which latter is carried to. the position vacated by "Y," and so ou through the
whole word "hydrogenium," when the remaining letters at the end will be found
in the following order: "L, A, F, P, Q,,C, S, T, K, V, W, X, B, Z," as shown.
The object of making one of the alphabets rotatable is to make it possible to shift

page_text: the alphabet one or more letters in one and the same direction for each letter
written down (or deciphered). So for instance the instrument may be used as
follows-
If hydrogenium be the keyword, and the correspondents have agreed that the
first letter of the communication is to be taken from the cryptograph when U in
the movable alphabet corresponds with A in the fixed alphabet, and that for each
following letter the movable alphabet is to be pushed 1 letter ahead, which is done
by depressing the lever at O, the alphabets will have the following position opposite
each other (Figure 1).
A B C D E F G H I K L M N O P Q R S T U V W X Y Z
UMLAFP Q C STK V W X B Z
-
P
-
HYDROGENI
,
UMLAFPQ C S T K V W X BZ —, ? HYDROGENI
If the letter begins with the word "DEAR" this will then in the cryptogram
read "A PL H."
The receiver of the cryptogram has then to follow the same rule when he
deciphers the letter. Cryptograms written in this manner cannot be deciphered by
anyone not knowing both the keyword, the initial letter and the rule for shifting
the alphabets during the use. Instead of loose letters in the inner alphabet, there
may be used rings with certain keywords thereon and which may be exchanged.
Or the disc may be made of a material such as celluloid or ivory, on which the
letters may be written with pencil.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me by
my foreign correspondents, 1 declare that what 1 claim is :-
1. In a cryptographic instrument, the combination with a fixed circular alphabet
of a concentric rotatable alphabet, one of the alphabets having interchangeable
letters substantially as described.
2. In a cryptographic instrument, the combination with a fixed circular alphabet
of a concentric rotatable alphabet one of the alphabets being interchangeable,
substantially as described.
3. In a cryptograph, the combination with a fixed and a rotatable circular
alphabet of means for moving the said rotatable alphabet.
4. In combination with the fixed circular alphabet of a cryptograph, a concentric
rotatable alphabet mounted on a disc having on its periphery as many teeth as the
number of letters in the alphabet and a lever having on each side of its pivot a
tooth which may be brought alternately in engagement with the teeth of the
alphabet wheel thereby pushing the same step by step in the same direction.

page_text: 5. In a cryptograph, the combination with the case A and its cover B of a
movable disc inside the case, a lever in engagement with teeth on the said disc said
lever having an arm projecting through the case.
6. A cryptograph substantially as specified and shown.
Dh 10th J. CAL
1001
WM. P. THOMPSON & Co.,
Agents.