Text Describing how the cipher works
Rule. -- First arrange a key-work, to be spelled alike by both. Write down the message, then over this write the key-word, re-peating as often as may be necessary to allow a letter of the key-word to each one in the message. Find in succession, in Table I, the letters of the key-word, in the left-hand column, and oposite, under the corresponding letter of the message, will be found the cipher letter. So continue to the end of the message. Let, for example, "Anchor" be the key-word -- & "Open fire" the message -- "OCGUTZRR" would be the cipher.
a n c h o r a n
o p e n f i r e
O C G U T Z R R
Rule. -- Write down the ciphers received, then over them the key-word, repeating as often as may be necessary, till each cipher has a letter of the key-word over it. Firnd in succession, in Table II, the letters of the key-word in the left hand column, and opposite, under the corresponding cipher letter, will be dound the letter of the message. So continue to end of cipher. -- To apply to figures: Let the letters a b c d e f g h i j represent the figures 1 2 3 4 5 6 7 8 9 0. In writing down the message, when figures occur, substitute these letters, preficing them by the letter Q and such other letters, from A to I, as shall indicate the number of letters following as figures. Then convert the whole into cipher as usual. In receiving a message, translate cipher, and for those letters indicated by Q, and the letter following, substitute the above figures. Example: QDAHGD would represent 1874.
Footnote on Page 2
Entered, according to Act of Congress, in the year 1874, by C.S. Larrabee, in the Office of the Librarian of Congress, at Washington.
For Use in the United States Navy