Improvements in Cryptographic Instruments.
Year: 1892

page_text: Date of Application, 7th Sept., 1892-Accepted, Sth Oct., 1892
COMPLETE SPECIFICATION.
Improvements in Cryptographic Instruments.
I, RICHARD HARTE of 1 Chatsworth Villas, Croydon, in the County of Surrey,
Journalist, 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 further improvements in cryptographic instruments such
as those for which I obtained previous Letters Patent dated July 11th 1891
No. 11838, and my present invention consists particularly in an improved construction
of the rectilinear form of instrument therein described and has for its object to
facilitate the employment of the instrument and lessen the liability of making
mistakes in translating a communication into or out of cipher by arranging in each
element of the instrument the alphabets and their corresponding indexes by which
the original and corresponding cipher letters are ascertained in such juxtaposition
that the two corresponding letters can be read off by glancing from one alphabet
to the other close alongside without requiring the eye to travel back and forth
along the columns of letters from one part of the instrument to another distant
therefrom and by appropriating for the purposes of the key-letter an additional
alphabet distinct from the alphabets used directly for translation and situated at a
part of the instrument sufficiently distant therefrom to avoid all liability of mistakes
which might ensue from confusion therewith. In this improved form of instrument,
each element comprises a fixed alphabetical series of letters (which may be termed
the normal alphabet) and a movable index in combination with another index
movable therewith as one and with a movable alphabetical series (which may be
termed the cipher alphabets) and an index which is adjustable with regard to a
third fixed alphabet, which may be termed the key alphabet and which bears a
constant relation to the first mentioned or normal alphabet, the movable cipher
alphabet and the key index last mentioned being constant with regard to each
other and moving together for the purpose of being set or adjusted with regard to
the fixed normal and key alphabets, so as to determine the relation of the normal
and cipher alphabets, according to the key-letter selected. The movable members
of this combination are fitted to work alongside the fixed members and are adjusted
with reference thereto by a rectilineal sliding motion. By arranging any number
of such elements side by side, a cryptographic instrument is produced which may
be conveniently used in connection with a key-word or sentence of any length.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein
Figure 1 is a plan view of the instrument and Figure 2 is a 'cross-section on line 1-1
Figure 1.
Figure 3 shews a detail of construction.
The same letters of reference denote like parts in all the figures.
The drawing illustrates an instrument comprising only five elements, but it will
be understood the number is capable of unlimited extension according to the length
of the key-word or sentence to be adopted, or the same clements may be re-set as
often as desired to complete the key-word or sentence. Each element comprises a
stationary strip A bearing the normal alphabet over or alongside of "which works
a sliding index a carried by a sliding strip a working alongside the strip A.
Adjacent to this strip a' is a fixed stripe and beyond this a sliding strip B.bearing
two complete cipher alphabets preferably arranged consecutively and in inverse
order to the normal alphabet A. is the index of the cipher alphabet B. It is
made in one with the index a and to avoid liability of mistakes it is preferably but
not necessarily placed out of line with the index a, and for the same reason the

page_text: <
alphabets A B are printed in different colors, but here shewn as in different type.
Upon the upper end of the strip B is carried an index c which works over a fixed key
alphabet C at the upper part of the instrument and is adjusted with regard thereto,
according to the key-letter selected and together with cipher alphabet B remains
stationary after being so set. Thus B and c move together and are constant with
regard to each other whilst a and b are also constant with regard to each other and
are adjustable with regard to A and B respectively so that the indication given by
the index will vary according to the adjustment of the cipher alphabet B. The
slides u' and B are fitted to slide in grooves in the base board of the instrument and
have handles by which they may be easily moved.
It is preferred to construct the instrument of cardboard by attaching the parallel
fixed strips A and C of that material to a base board D of the same or other solid
material so as to leave grooves between the said strips in which the movable strips a¹
and B slide. The upper and lower portions of all the strips are covered by top
plates of cardboard E, F, leaving uncovered the middle portion of the instrument
at which the alphabets A, B, are visible, and in which space the indexes a b.work.
The movable strips slide beneath these cover plates and in the upper cover plate E
are a series of apertures e at which the key alphabets C are visible and in which
the indexes c work. The several indexes are preferably attached to their respective
strips, by a wire staple of the form shewn in Figure 3 provided with upwardly
projecting bends or offsets f¹ which can be conveniently grasped between the finger
and thumb for the purpose of shifting the sliding strips. The indexes a bare
preferably formed with a gap disclosing the letter indicated and covering the
adjacent letters, so as to avoid liability of error.
The instrument may be used as follows:-Suppose the name "HARTE" to be
selected as the key, the several key indexes c of the five combinations of elements
composing the instrument are set to the several letters of that key-word as shewn.
Suppose the word to be translated into cypher to be the name "CLARK," this may
be done by bringing the several indexes a to the several letters of that word on the
normal alphabets A as shewn whereby the indexes bare brought opposite the several
letters "FPR CU" on the different cipher alphabets B which letters are the
cyphers corresponding to the word to be transmitted. To retranslate this cypher-
word, the recipient, having set the indexes c of his instrument to the key-word
HARTE," brings the indexes a to the cipher letters "FPRCU" on the
normal alphabets A and reads off the message "CLARK" on the cipher alphabets B
at the indexes b.
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 cryptograph or instrument for translating communications into or out of
cipher, consisting essentially of the combination of a fixed normal alphabet strip,
a movable cipher alphabet strip adjacent thereto, a double movable index working
over both of said alphabets, the movable cipher alphabet being adjustable with
regard to the first mentioned normal alphabet and to another fixed or key alphabet
by means of an index carried by the movable cipher alphabet strip, substantially as
specified.
2. A cryptograph or instrument for translating communications into or out of
cypher, consisting essentially of the combination of a fixed normal alphabet strip,
a movable cipher alphabet strip adjacent thereto, a double movable index working
over both of said alphabets, the movable cipher alphabet being adjustable with
regard to the first mentioned normal alphabet and to another fixed key alphabet by
means of an index carried by the movable cipher alphabet strip, substantially as
specified, the key-letter, index, and key alphabet, being visible at an aperture in
the instrument frame removed from the normal and cipher alphabets directly used
in translating so as to avoid confusion therewith, as described.
3. A cryptograph constructed of a combination of two or more elements, each

page_text: element consisting of the combination of a fixed normal alphabet strip, a movable
cipher alphabet strip adjacent thereto, a double movable index working over both
of said alphabets, the movable cipher alphabet being adjustable with regard to the
first mentioned normal alphabet and to another fixed key alphabet by means of
an index carried by the movable cipher alphabet strip substantially as specified.
4. The herein described instrument constructed of parallel strips fixed to a base
plate, intermediate sliding strips working in grooves alternating with the fixed strips
normal and key alphabets carried on the fixed strips, a double index on each
alternate sliding strip, a double cipher alphabet on the remaining sliding strips, and
an index on each of those strips adjustable with regard to one of the first mentioned
fixed alphabets, as specified.
5. In the herein described cryptograph, constructing the double index with
gaps at opposite ends out of alignment with each other, as described.
6. In the herein described cryptograph, the combination, with the sliding strips
and index pieces, of wire staples securing the indexes to the strips and having
upward bends or off-sets to form handles whereby to adjust the said indexes, as
lescribed.
Dated this 7th day of September 1892.
By A. M. & Wm. Clark,
K. HARTE,
53, Chancery Lane, London, Chartered Patent Agents.