Improvements in Cryptographic Instruments.
Year: 1896

page_text: Date of Application, 28th July, 1896
Complete Specification Left, 16th Nov., 1896-Accepted, 24th Dec., 1896
PROVISIONAL SPECIFICATION.
Improvements in Cryptographic Instruments.
I, RICHARD HARTE of 59, Gray's Inn Road in the County of Middlesex,
Gentleman, do hereby declare the nature of this invention to be as follows:-
My invention relates to an improved cryptograph or instrument for use in
composing and deciphering communications in cipher, and it has for its object to
provide an instrument of extremely simple construction and portable form so that
it may be carried in the pocket and which by reason of the great number of
permutations of which it is susceptible as regards adjustment and mode of working
enables the relation between the original and cipher letters to be varied indefinitely
and in such way that in the same communication the same original letter may be
represented where it recurs in different places by different equivalents or cipher
letters so that a communication may be disguised in a way which is absolutely
undecipherable, notwithstanding that the "key" is formed by a very simple.
elementary combination of letters.
The instrument may be of circular or straight form, the circular rotary
construction being preferred for convenience of portability, and the invention will
be described with reference to this form.
It consists of a base or stationary portion bearing one or more complete alphabets
of which the letters may be arranged consecutively in alphabetical or any other
pre-arranged order and which may be variable in order as may be agreed upon by
the two correspondents employing the instruments. Upon this base is a rotating
part carrying a plurality of indexes angularly adjustable with regard to each other
according to any pre-arranged combination of letters used as a "key," these
indexes when once adjusted being either moved together as one with regard to the
alphabet or alphabets in using the instrument, or one or more of the indexes being
capable of a certain regulated angular motion independently of another index used
in conjunction therewith, the indexes moving together as one when this limited
angular motion is exceeded. In either case by rotating the index-bearing portion
to right or left so as to bring one or other index in succession opposite to the
letters on the stationary base portion which represent the communication to be
disguised and by reading off from the same alphabets the letters to which the one or
the other of the other indexes is brought opposite (the one or the other index being
used in alternate or any other pre-arranged order) cipher letters which represent
the letters of the original communication may be read off at those indexes. These
equivalent or cipher letters will differ according to the adjustment of the indexes
inter se, according to the order of sequence in which the indexes are used in reading
off the cipher, and according to the extent of independent angular motion above
referred to.
The operaton of deciphering a communication is similar as regards the order of
movements so that the letters of the cipher communication are referred by the
receiver to the same indexes as those by which they were read off by the
sender in composing the cipher communication, the letters of the original
communication being therefore read off at the index to which they were referred.
by the sender.
Dotad this 28th dot of July 1806
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.

page_text: 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 an improved cryptograph or instrument for use in
composing and deciphering communications in cipher and it has for its object to
provide a simple and portable form of instrument which may be carried in the
pocket but which, by reason of the great number of permutations of which it is
susceptible as regards adjustment and mode of working, enables the relation between
the original and cipher letters to be varied indefinitely and in such way that the
same original letter may be represented where it recurs in different places in
the same communication by different equivalents or cipher letters so that a
communication may be disguised in a way which is absolutely undecipherable
notwithstanding that the "key" is formed by a very simple elementary combination
of letters.
The invention will be described with reference to the accompanying drawing
which represents a face view of the preferred construction of the instrument.
The instrument consists of a base or stationary portion A bearing one or more
complete alphabets of which the letters may be arranged in a circle either in
alphabetical order or promiscuously, provided that the order of arrangement be similar
in the two instruments used by the two correspondents between whom the cipher
communication is to be established. Upon this base A, a rotary part B is pivoted.
It carries a plurality of indexes C DE, one being fixed to the part B and the other
two being angularly adjustable with regard to it and to each other so that they
may be set according to any pre-arranged combination of letters serving as a "key"
for the cipher communication, these indexes when once adjusted being moved
together as one in using the instrument. For the sake of distinction these
indexes D E may be differently coloured or otherwise rendered easily distinguishable
from one another.
The rotary part B may conveniently be made of two thicknesses of vulcanite 6 61
or other material and the adjustable indexes D E may be lodged between these
two thicknesses and pivoted about a common centre a so as to be independently
adjustable and yet rotate with the part B without disturbance of their adjustment.
The base A is preferably made of vulcanite and provided with a raised marginal
rim a¹ to protect the alphabet from injury. The alphabet is preferably printed or
impressed on a separate disc A¹ of card, xylonite, or other suitable material held in
place upon the base A, the order of the letters being preferably changed for every
pair of instruments so that in addition to the permutations obtainable by adjusting
the indexes inter se, and by varying the order in which they are used, a further
change is obtainable by varying the order of the letters themselves. The two
discs 66 are united at the segmental parts denoted by the dotted lines 63 80
as to cause them to turn together and also limit the angular adjustment. of the
indexes D E. The part B pivots preferably on a central boss a rising from
the base A and is provided with a finger loop or handle to facilitate
turning it. It is held in place by the head G of a screw stud 9 screwing into
the boss a.
To set the instrument the index C is placed at the letter "A," or any other
preconcerted letter of the alphabet, and the indexes D E are moved until they
point to any two letters within their range of adjustment. These letters constitute
the "key" of the communication. Then by rotating the disc B to right or left so
as.to bring the index C-successively opposite to the letters of the alphabet which

page_text: spell out the communication to be disguised, and by at same time reading off the
letters to which the one or other of the indexes D E is brought opposite (the
reading off at the one or the other index being done in alternate or any other
preconcerted order) the letters so read off serve as cipher letters to represent the
letters of the original communication. These equivalent or cipher letters will
differ according to the arrangement of the alphabet, the adjustment of the indexes,
and the order of sequence in which the indexes D E are used in reading off the
cipher letters.
The operation of deciphering a communication is converse but similar as
regards the preconcerted adjustment of the indexes and the order in which the
cipher letters are referred to them, the part B being turned so as to point the
indexes D E, in preconcerted order successively, to the letters of the cipher
communication, the original communication being then read off at the index D.
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. A cryptographic instrument consisting in the combination, with a part
carrying an alphabet, of a movable part carrying two or more indexes adjustable
with regard to each other and movable together as one with regard to the
alphabet substantially as described for use in the manner and for the purpose
specified.
2. The herein described cryptographic instrument constructed of the parts
specified, arranged and combined for use substantially as specified.
Dated this 16th day of November 1896.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.