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Fig. 11.—A Government cipher, called the “Sphinx.”

Suppose that the key-word chosen is BALFOUR, and that the message to be sent is WAR DECLARED LEAVE NOW, the key-word is then applied to the message thus:—

You then find in the top row the first letter of your message, which is W, and you see that the letter on a line with B and under W is X, which will be the first letter of your cipher. You then find A above and A by the side, which will give you C. You then find R above, and in the L horizontal column is its equivalent U. Proceeding thus with your message you arrive at the cipher, which reads: XCU HJISBTHH QKHWG QSB.

To read this it is only necessary to write the key-word under the cipher and reverse the proceeding.

An ingenious cipher, used by the War Office of a well-known Continental Power, is partially shown in [Fig. 12].

On two adjacent sides of a square entire alphabets are written, commencing at any letter (in the figure they begin at K in one and S in the other). Against each letter of the perpendicular alphabet the entire twenty-six letters are written horizontally, beginning with A and continuing in order. Leaving the first of these horizontal alphabets simple, against the remaining twenty-five, small alphabets are written as you will see in the figure, which shows the plain alphabets and five letters so treated.

Fig. 12.—Another Government cipher—still in use.

The cipher is used in this way. The letters in each word of the message are divided into couples. These couples are found in the doubled alphabets in the center of the cipher scheme, and the key letters at the side and top show the actual cipher equivalent.