Improvements in Means for and in the Method of Writing and Deciphering Communications in Figure Cipher.
Year: 1890

page_text: Date of Application, 9th Dec., 1890-Accepted, 17th Jan., 1891
Improvements in Means for and in the Method of Writing and
Deciphering Communications in Figure Cipher.
I, EDWARD DE LANOY LITTLE, of the Mount, Northallerton, Master of Arts, do
hereby declare the nature of this invention and in what manner the same is to be
performed, to he particularly described and ascertained in and by the following
statement :-
In the Specification of my invention, Patent No. 16,159, dated 14th October 1889,
I provide for the writing and reading, or deciphering, of telegraphic and other com-
munications in two different kinds of cipher or secret writing, viz. :-in letter cipher,
and in figure cipher; and, for both these purposes I apply one moveable dial, disc
or plate to the fixed scale of a type-writer or cryptograph; which definition I
interpret to be an instrument for indicating without recording cipher or secret writing.
In that invention the figure-cipher is obtained by bringing every character in the
moveable scale opposite a figure in the fixed scale, which involves the use of a triple
or even quadruple scale.
In the present invention I employ separate dials, plates, or scales, in letter cipher
and figure cipher respectively, and obtain the figure-cipher by writing a figure under
every character in the moveable scale, thereby obviating the need for the triple, or
quadruple scale. I furthermore provide for the more complete secrecy of the resulting
figure-cipher by constructing parts or the whole of the discs, dials or plates employed
of material capable of receiving writing which can be erased at pleasure. A dial
"slate."
or plate of such a material will be referred to hereafter as a
The following description of instruinents and the accompanying drawings will for
the sake of clearness be confined to a single kind of typewriter and a corresponding
cryptograph, and it will be assumed that the character-scale or alphabet of the move-
able scale is in the reverse order to that of the fixed scale; but the invention is
applicable to almost any typewriter, and the order of the alphabet of the fixed scale
can be preserved in the moveable scale, provided that in deciphering, the moveable
scale be moved as many places in one direction from the normal position as it is
moved in the other direction during the operation of ciphering.
In order that the nature of my invention may be the better understood I have
appended the annexed explanatory drawings.
Figure represents a moveable cipher disc or plate bearing almost precisely the
same scale of 36 letters and figures as the dial of a "Miniature Pocket Type-writer "
Figure 2, but in reverse order, and divided into four equal compartments distinguished
by one, two, three and four dark spots respectively. The & of the type-writer is
replaced by 0, and, in the place of the is a vacant space, g, Figures 1 and 3 through
which one character of the typewriter scale is visible when the moveable cipher
disc is attached to the type-writer. Under the characters in each of the com-
partments the nine digits from 2 to 0 are written in order.
Figure 2 represents the dial of a "Miniature Pocket Type-writer" prepared for
the attachment of the cipher disc seen in Figure 1. a is the dial face of the type-
writer is a metal ring screwed down to the dial; c is a slate dial, fixed within
the ring b, on which are drawn lines marking the division of the type writer dial
into four equal compartments, corresponding to those of the cipher disc, and dis-
tinguished in the same manner; d is the handle of the type-writer by means of
which the uial is set in rotation, and raised or depressed; e is a screw-collar
working externally on the ring 6 and serving to clamp the cipher disc to the dial
of the type-writer.
Figure 3 represents the same type-writer dial with the cipher disc attached. On
the inner dial and the cipher disc are written effaceable figures of which the use
will be hereafter explained.

page_text: Figure 4 represents a cryptograph consisting of two concentric slate dials, one of
which moves upon the face of the other on their common axis. The scale of characters
on the larger or outer dial corresponds to the fixed scale of the type writer, Figure 2,
except that 0 has been substituted for &, and it is similarly divided into four com-
partments. The smaller dial bears a scale identical with the figured scale of the
cipher disc, except that the space occupied by is not cut away, and it is divided
similarly into four compartments. On the inner part of this dial and on the edge of
the larger dial are written effaceable figures which will be explained hereafter.
Having described these instruments I proceed to explain their uses, and if the
differences noticed in the next paragraph be borne in mind, the same explanation will
serve for both instruments, and, any doubt as to the results obtained by the type-
writer. Figure 3, may be verified by reference to the cryptograph, Figure 4.
In using the type-writer for cipher-writing the fixed or true scale, i.e., the scale of
which the characters are actually written, is invisible, and its characters can only be
read after being actually written down; whereas in using the cryptograph the fixed
scale is visible, and its characters can be read off without writing them down. Also,
in the type-writer, the division of the fixed scale into compartments, the scale itself
being invisible, is shown on the innermost dial, and that of the moveable scale on
the outer disc; whereas in the cryptograph the division of the fixed scale which is
visible is shown on the scale itself on the outer dial, and that of the moveable scale
on the inner dial.
On examining the moveable scale of either instrument it will be seen that any
character can be symbolised by two digits; one being the digit standing under it, and
the other some digit to indicate the compartment in which the character in question
occurs. Thus, B having under it the digit 4, and being in the first compartiment is
sufficiently indicated by the symbol 41 or 14; Z having 0 under it and being in the
third compartment by the symbol 03, or 30; 6 by 64 or 46, and so forth. But, in
order to make the cipher more difficult of detection, instead of denoting the four
compartments by fixed symbols, I vary the symbols, and for this 'purpose write
effaceable figures on the compartments of each dial.
The process of writing in figure-cipher will then be effected as follows:-
Suppose that it is required to write in figure-cipher the word "SEND." The
operator having arranged with his correspondent the key character, which in the
drawings is K, will place or the vacant space of the moveable scale opposite or
over K in the fixed scale, and will proceed to write in the four compartments of
the moveable dial or disc the nine digits from 2 to 0, distributing them as be
pleases, or according to agreement with his correspondent. Suppose him to assign
to the first compartment 6, 8, 0; to the second 3, 2; to the third 9, 7; and to
the fourth 4, 5. Then, in order to write the cipher for S, he will look for S in
the moveable scale, and seeing that it has 3 under it and is in the third compart-
ment, to which he has assigned the symbols 9, 7, he will take either 39, or 37,
or these figures reversed, as the symbol for S, and will proceed to cipher one of
these symbols. This he will do with the type-writer by apparently writing 3, 9,
or 3, 7, or the reverse with that part of the moveable scale which stands opposite
the fourth or figure compartment of the inner dial, shaded in the drawing; with
the cryptograph by writing down the figures in the fourth compartment of the
outer scale, shaded in the drawing, which stands opposite 3, 9, or 3, 7, or the reverse,
in the moveable scale. The resulting cipher is 3, 6, or 3, 8, or the reverse. Similarly
the symbol for E is 7, 6; 7, 8; or 7, 0; and its cipher is 8, ; 8, 7; or 8, 5; the
symbol for N is 7, 2; or 7, 3; and its cipher is 8, 4; or 8, 3; the symbol for D is
6, 6; 68; or 6,0; and its cipher is 9, 9; 9, 7; or 9, 5. Hence, the cipher for
SEND" is any combination of these alternative ciphers as for instance
"
66 3 6 8 5 8 49 9."
It must be observed that the figure () does not occur in the fixed scale of the type-
writer, but is replaced by &. It therefore, in the position figured, 5 is ciphered
directly, the resulting cipher will be & which will have to be corrected by hand into 0.
It will perhaps be better to ascertain by trial beforehand the cipher for the letter O,

page_text: which, in the position figured is 7, and whenever it is necessary to cipher the symbol 5
as for instance in ciphering Cor L, to cipher 7 from the upper line of the moveable
scale, as the resulting cipher will be 0.
It now remains to explain the process of reading or deciphering figure-cipher.
Suppose that it is required to read the cipher obtained above:-36 85 849 9."
The operator must be in possession of the key, and must either have arranged
beforehand with his correspondent the figures used as the symbols of the compart-
inents, or have had them communicated in the message itself. In either case he will
first adjust his instrument to the proper key and will cipher his correspondent's
symbols for the compartments. In the supposed case these were 6, 8, 0; 3, 2; 9, 7;
4,5; of which he will find the ciphers to be 9, 7, 5; 3, 4; 6, 8; and 2, 0, respec-
tively. He will then insert 9, 7, 5; 3, 4; 6, 8; and 2, 0, in the first, second, third
and fourth compartments respectively of the fixed scale. He will now look for that 3
in the moveable scale which lies opposite the compartment of the fixed scale symbolised
by 6, viz. the third, and write it. The resulting cipher, as will be seen in the crypto-
graph, will be S. Similarly the 8 in the moveable scale opposite the compartment of
the fixed scale symbolised by 5, or the first, will be written and result in E; the 8
opposite the compartment symbolised by 4, or the fourth, will be written N; the 9
opposite the compartment symbolised by 9, or the first, will be written D.
It is not claimed that the figure cipher obtained by the instruments described above
would present any great difficulty to the skilled cryptographer, provided that he were
acquainted with the order of the alpbabet of the instrument employed, but it would
suffice to baffle ordinary curiosity, and its difficulty may be much increased by
preconcerted changes of key, and of the order of the variable numbers employed,
during the operations of ciphering and deciphering. It must be remembered also
that there are in existence many type-writers with various alphabets, and one at least
in which the alphabet is variable et pleasure, and that to many or most of these the
invention is applicable, so that it is very improbable that the alphabet of the
instrument employed would be known to anyone but the correspondent for whom
the cipher was intended.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is :-
First The hereinbefore described method of and means for writing and deciphering
communications in figure cipher by means of typewriters and of indicating the same
results by means of a cryptograph substantially as specified.
Second In connection with the hereinbefore described means for and method of
writing and deciphering in figure cipher by means of typewriters and of indicating
the same results by means of a cryptograph, the employment of the scales herein
referred to substantially as and for the purposes specified.
Third In connection with the herein before described means for and method of
writing and deciphering in figure cipher by means of typewriters and of indicating
the same results by means of a cryptograph, the use in the construction of the scales
referred to in the preceding claim of such materials as enable correspondents to
introduce continual changes into the scales substantially as and for the purposes
specified.
JAMES STEVENSON,
Gray's Inn Chambers, 20, High Holborn, London, W.C., Agent for Applicant.