Improvements in Cryptographic Instruments.
Year: 1896

page_text: Date of Application, 1st Apr., 1896
Complete Specification Left, 4th Aug., 1896-Accepted, 5th Sept., '894
PROVISIONAL SPECIFICATION.
Improvements in Cryptographic Instruments.
I, RICHARD HARTE of 59, Gray's Inn Road, in the County of Middlesex,
Journalist, do hereby declare the nature of this invention to be as follows:-
My invention relates to improvements in cryptographic instruments for use in
composing and deciphering cipher communications.
The instruments are of the kind for which Letters Patent were granted to me
dated the 7th day of September 1892 No. 16,069; and the present improvements
have for object to simplify the construction and facilitate the use thereof.
The general construction of the instrument is somewhat similar to that previously
described but is more compact, there being a lesser number of alphabets and fewer
sliding strips, and special means are provided of combining together a number of
similar instruments in a simple portable and convenient form for use when an extended
key-word or sentence is employed.
The present instrument consists of a body board with juxtaposed grooves for
sliding alphabet-bearing strips to run in the strips being dissimilar as regards
the positions of the letters composing the cipher alphabets and being interchange-
able as regards their order of arrangement on the board which is determined by
distinguishing cipher index letters or figures.
According to one arrangement the letters of the alphabets which are actually
used in the composition and deciphering of a communication are visible singly
at apertures in the covering face of the board so that the liability of error is
greatly lessened, each strip bearing two complete alphabets printed in columnar
form, viz. a normal alphabet from A to Z and a cipher alphabet whereof the
letters run in reversed order, the cipher alphabets of different strips commencing
and ending with different letters so that whilst the cipher alphabet of one strip
commences at Z and terminates at A the terminal letters of the cipher alphabets
of the other strips are respectively at Y Z, X Y, W X, and so on; although each
comprises the whole twenty-six letters so that for different strips different cipher
letters correspond to the same letters of the normal alphabet, the corresponding
letters of the normal and cipher alphabets appearing at their respective apertures
simultaneously. Therefore by interchanging the strips in their grooves so as to
make their index letters or figures accord with the cipher key adopted, the instru-
ment will be ready for use in composing or deciphering a communication in
accordance with that key, the cipher key being susceptible of indefinite variation
and of any length from a mere word or combination of letters or figures to a
continuous sentence or even an entire book, it being however necessary to inter-
change the strips as the variation in the cipher key progresses.
Thus in using the instrument the communication to be disguised is spelt out at
the apertures shewing the normal alphabets by shifting the strips in their grooves
the corresponding cipher equivalents in the cipher alphabets appearing at their
apertures. These having been copied out the communication is continued by
repeating the operation as often as required, the positions of the strips being
interchanged previous to each repetition of the operation if the cipher key is a
continuously varying one.
The operation of deciphering a cipher communication is exactly similar the cipher
alpbabets then playing the part of deciphering alphabets.

page_text: According to another arrangement each sliding strip has only one alphabet,
these being the cipher alphabets and being dissimilar in arrangement, inter se, the
normal alphabets being marked upon the fixed division strips which separate the
grooves for the sliding strips. The normal alphabets are fully visible and
the sliding strips bearing the cipher alphabets are provided with index marks
or pointers which are adjusted with reference to the adjacent normal alphabets, the
letters of the cipher alphabets then shewing singly through apertures in the face of
the tablet according to the adjustment of the strips.
In order to avoid interchanging the same strips so frequently, as many similar
instruments may be combined together as the length of the key may require to form
the elements of one large and easily folded and portable instrument. by means of
two pairs of elastic webs, the webs of each pair being fastened together at intervals
to form loops adapted to embrace the top or bottom end of each element which are
thus hinged together for folding or extending as required and are readily combined
or separated as desired.
Dated this 1st day of April 1896.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.
improveme
ographic Instruments.
I, RICHARD HARTE of 59, Gray's Inn Road in the County of Middlesex,
Gentleman, 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 :-
My invention relates to improvements in cryptographic instruments for use in
composing and deciphering communications in cipher.
The instruments are of the kind for which Letters Patent were granted to me
dated the 7th day of September 1892 No. 16,069; and the present improvements
have for object to simplify the construction and facilitate the use of such
instruments.
In general construction the instrument is somewhat similar to that previously
described but it is more compact, there being a lesser number of alphabets and
fewer sliding strips and special means are provided of combining together &
number of similar instruments in a form admitting of being easily folded for
transport and convenient for use when an extended key-word or sentence is
employed.
In the accompanying drawings forming part of this specification I have illustrated
in Figures 1 and 2 two modifications of the instrument and in Figure 3 a means by
which several such instruments may be temporarily connected for use in an easily
foldable form.
The present instrument consists of a body board or tablet with juxtaposed
grooves for sliding alphabet-bearing strips to run in, the strips being dissimilar as
regards the positions of the letters composing the cipher alphabets and being
interchangeable as regards their position on the board, their order of arrangement
being varied at will in accordance with any arbitrarily selected key-word, sentence,
or combination, the user being guided in the arrangement of the strips by
distinguishing cipher index letters or figures as shewu at a.
According to the arrangement illustrated in Figure 1, each sliding strip a' a² a etc.
bears two complete alphabets printed in columnar form viz. :-at the lower part a
normal alphabet extending from A to Z in consecutive order reading downwards
and at the upper part a cipher alphabct whereof the letters may run in reversed
order, that is to say in consecutive order reading upwards except that the cipher

page_text: alphabets of different strips commence and end with different letters so that whilst
the cipher alphabet of the strip al commences at Z and terminates at A the
terminal letters of the cipher alphabets of the other strips a³ a³ a¹ etc. are
respectively Y Z, X Y, V W, and so on, that is to say such cipher alphabets are
differently arranged each from the others although each comprises the whole
twenty-six letters so that for different strips different cipher letters correspond to
the same letters of the normal alphabet.
In this modification of the instrument the letters of the normal alphabet which
spell out the communication to be composed in cipher or to be deciphered are
caused by the sliding of the strips a' as a³ etc. to appear at an aperture in the
covering face c of the board at the same time that the corresponding letters of
the cipher alphabets appear at another aperture d so that the remainder of the
letters being concealed by the covering face c the liability of error by the eye
being confused or fatigued by a multiplicity of letters is greatly lessened. The
letters supposed to be so concealed are represented in the drawings as being dotted
merely to indicate their positions.
By interchanging the strips a' a a³ etc. in their grooves g so as to make their
index letters or figures a accord with the cipher key adopted (which as before
stated may be a word or combination of letters or figures repeated as often as
required or be continuously varied according to any arbitrarily selected key) the
instrument will be put in condition for use in composing and deciphering a com-
munication in accordance with that key the cipher key being susceptible of
indefinite variation since it may be of any length from a mere word to a continuous
sentence or even an entire bock, it being understood that it is necessary to
re-arrange the strips or replace the strips as the variation in the cipher key
progresses.
Thus in using the instrument the communication to be disguised is spelt out at
the aperture or apertures shewing the normal alphabets by shifting the
strips a' as a etc. in their grooves g the corresponding cipher equivalents in the
cipher alphabets appearing at the aperture or apertures d. These having been
copied out the communication is continued by repeating the operation as often as
required, the strips a' a3 as etc. being altered in position or replaced by others
previous to each repetition of the operation, if the cipher key is a continuously
varying one.
In the example illustrated the communication required to be translated into
cipher is the word "cryptogram" which it will be seen is represented by the cipher
letters X H ZG BD FR G T it being assumed that the cipher key is the
sequence of figures 0 1 2 3 4 5 6 7 8 9.
The receiver of the cipher communication X H ZG BDFR G T being
possessed of a similar apparatus is supposed to have arranged the alphabet strips in
their grooves in accordance with the pre-arranged key and by then shifting the
alphabet strips so that the cipher communication appears at the one aperture the
communication in ordinary language may be read off at the other.
It has been assumed that the cipher alphabets (although commencing and ending
with different letters in the various strips) are each formed of letters in consecutive
order but this is by no means necessary. The order of the letters may in fact be
promiscuous and varied according to any one of half the number of permutations
of which the twenty-six letters of the alphabet are susceptible, the limitation being
a reciprocal correspondence, that is to say that if a given letter (c for instance) of
the cipher alphabet corresponds to a letter (N for instance) of the normal alphabet
then the letter c of the normal alphabet and the letter N of the cipher alphabet
must correspond and so on for all the others.
According to another modification represented in Figure 2 each sliding strip a¹
aa etc. carries only a cipher alphabet, these cipher alphabets being dissimilar in
arrangement inter se as above described whilst the normal alphabets are marked
upon fixed division stripsf which separate the grooves g for the sliding strips a
a² a³ etc.
The normal alphabets are fully visible and the sliding strips a' a² a³ etc.

page_text: are provided with indexes or pointers which are adjusted with reference to the
adjacent normal alphabets on the stationary strips f, the corresponding letters of
the cipher alphabets then shewing singly through an aperture or apertures d in the
covering face c of the tablet.
In order to avoid the frequent interchanging of position of the strips or their
replacement by others bearing cipher alphabets differently arranged, as many
similar instruments may be combined together as may be convenient according to
the length of the key adopted the several instruments so combined forming the
elemental parts of one large and easily folded and portable instrument. For this
purpose two pairs of elastic webs, such as shewn at k in Figure 3, are provided,
the webs of each pair being fastened together at intervals as shewn at 1 so as to
form elastic loops adapted to embrace the top or bottom end of each elemental
part, the several elemental parts thus hinged together being connected in a form
convenient for conjoint use when displayed, or for being folded on one another for
transport.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The improved construction and arrangement of cryptographic instrument
substantially as herein specified with reference to Figures 1 and 2 of the
drawings.
2. The herein described means of uniting several such instruments in a form
easily developed for use or folded for transport as specified.
Dated this 4th day of August 1896.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.