Improved Method and Apparatus for Facilitating the Writing and Reading of Cipher Messages.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improved Method and Apparatus for Facilitating the Writing and
Reading of Cipher Messages.
I, LYNDWODE CHARLES PEREIRA, of the City of Ottawa in the County of
Carleton and Province of Ontario, Dominion of Canada, Assistant Secretary of the
Department of the Interior of Canada, 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 cipher codes of the "Slater" type which are composed
of words and numbers, and has for its object to render the preparation of a cipher
message and its subsequent translation less troublesome and much more rapid than
heretofore.
For this purpose, I prepare a gauge preferably formed of metal in the shape of a
paper knife, having its edge graduated with divisions corresponding with the lines
of the words in the code book, having an adjustable index which can be set to any
division and fixed by a screw.
By the use of this gauge I avoid the necessity for figuring on paper, and for
troublesome calculation, and I greatly lessen the risk of errors in writing or reading
a cipher, as I shall explain referring to the accompanying drawings.
Fig. 1 represents the gauge and Figs. 2, 3 and 4 are views of a code book opened
with the gauge applied, as required for use.
The code systems to which I refer are usually and preferably arranged in double
columns each of 50, or in a single column of 100 words to the page, so that in working
the code, where the addition of a given key number in writing the message and its
deduction in deciphering have to be made, it is only necessary to consider the tens
and units under 50 and 100 respectively of the cipher number.
Assuming that the key number is 500 to be added in transmitting and deducted
in translating, and that it is desired to send a message one word of which is "wheat."
The sender finding the word "wheat" in the code say on page 60 lays the gauge A
as shown in Fig. 2 and sliding the index B to face the word, fixes it by turning the
set screw C.
He then turns over to page 65 and setting the gauge along the same column as
on page 60 the pointer indicates the 50 th. word from "wheat" which word we
may suppose is "yesterday.". This word is written instead of the word "wheat."
The rest of the words of the message are determined in the same way and the
receiver has only to reverse the order of operation, that is, to set the gauge and go
backwards 500 words in each case.
If the key number is 519, the sender sets the index at 19 on the gauge, notes the
unit or ten opposite the word in the code book as for example the unit 6 of the
number 24,006 which is opposite the word "wheat on page 60. He then
turns over to page 65 and lays the gauge on the corresponding column, as shewn in
Fig. 3, with its zero point opposite the word which has the unit 6 and the index
at 19 points out the word required, which is the 519th. from "wheat."
When the key number runs beyond the end of a column, as it would do if it
were 269, if the word to be transmitted came within 19 of the last or bottom word
of the column, the index would have to be set at number 19 on the gauge; then
2 pages and a column of 50 making in all 250 words being turned or passed the gauge
would be laid to this column with the index opposite the last word in the column;
the index is then moved back as shewn in Fig. 4 to the word and number from which
the 19 additional words should have started, when the gauge will give the number
of words to be taken off the top of the following column.
To translate a cipher, the receiver reverses the operation in every case and, as
before described, gauges the required number and measures backwards.

page_text: It will be seen that the use of the gauge effects very great saving of time both ir
sending and deciphering the messages, particularly where the key number happens
to be within the thousands such as 1995, as where the columns are arranged in fifties
the tens and units over 1950 are simply marked off on the gauge and the remaining
numbers in the book.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what
I claim is
1. For writing and translating cipher messages, the herein described method of
determining the required words for a given key number, the fifties and hundreds of
which are counted in the code book and the intervening tens and units upon a hand
gauge.
2. As apparatus for facilitating the writing and translating of cipher messages, a
hand gauge having its edge graduated in correspondence with the lines of a code
book, and provided with an adjustable index, substantially as described.
Dated this 12th day of June 1891.
ABEL & IMRAY,
Agents for the Applicant.