Cryptology Through History and Inquiry

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Suppose the keyword to be “antipodes”

a n t i p o d e s a n t i p o d e s a n t i p o d e s
t h e m a n w h o s e m i n d o n v i r t u e b e n t
u v y v q b & m g t s f r e s s s n j e m c u q i t m

then copy out the cyphered line thus, uvyvqb&mgtsfresssnjemcuqitm

numbers are thus, 18 is bv 1798 is thus bubq

the method is this.

look for t in the \(1^{st}\) vertical column & a in the \(1^{st}\) horizontal one gives u

From a cylinder of white wood of about 2 inches in diameter and 6 to 8 long bore through the center a hole sufficient to receive an iron spindle or axis of 1/3 or 1/2 inch diameter. Divide the perimeter into 26 equal parts (for the 26 letters of the alphabet) and with a sharp point draw parallel lines through all the points of the division from one end to the other of the cylinder, and trace those lines with ink to make them plain. Then cut the cylinder end wise into pieces of about 1/6 of an inch thick, they all resemble backgammon men with plane sides. Number each of them as they are cut off, on one side, that they may be arranged in any order you please. On the perimeter of each & between the black lines, put all the letters of the alphabet, not in their established order, but jumbled & without order so that no two shall be alike. Now string them in their numerical order on an iron axis, one end of which has a head and the other a nut or crew the use of which is to hold them firm in any given position when you chose it. They are now ready for use, your correspondent having a similar cylinder similarly arranged.

Suppose I have to cypher this phrase “Your favor of the \(22^{nd}\) is received.”

I turn the \(1^{st}\) wheel till the letter y presents itself

  turn the \(2^{nd}\) and place it's o by the side of the y of the \(1^{st}\)

  turn the \(3^{rd}\) and place it's u by the side of the o of the \(2^{nd}\)

  turn the \(4^{th}\) and place it's r by the side of the u of the \(3^{rd}\)

  turn the \(5^{th}\) and place it's f by the side of the r of the \(4^{th}\)

  turn the \(6^{th}\) and place it's a by the side of the f of the \(5^{th}\)

  and so on till I have got all the words of the phrase arranged in one line, fix them with the screw. You will observe that the cylinder then presents 25 other lines of letters, not in any regualr sense, but jumbled & without order or meaning. Copy one of them in the letter to your correspondent. Then he receiving it, he takes his cylinder and arranges the wheels so as to present the same jumbled letters in the same order in one line. He then fixes them with the screw and examines the other 25 lines and finds one of them presenting him these words “Your favor of the \(22^{nd}\) is received” which he understands. As the others will be jumbled & have no meaning he cannot mistake the true one intended.