Cryptography.
From very ancient times secret writing, known as cipher (from the Arabic sifr, "void"), or cryptography (from the Greek "hidden writing"), has been an important means of communication. In great national crises, where absolutely secret communication was necessary, it has saved much time and trouble. Charles I. wrote his famous letter to the Earl of Glamorgan in cipher, consisting of variously shaded and lengthened strokes of the pen. This letter was afterwards deciphered, and proved to be a concession to the Roman Catholics of Ireland, which, if generally known at the time, would have caused serious trouble. Lord Bacon also made frequent use of the cipher but even his ingenious methods have since been discovered.
There are many methods. Perhaps the most common is the variety found in one of the Sherlock Holmes tales, where, in a seemingly plain, every-day sentence, words set at intervals give the hidden meaning. Poe's fascinating "Gold-Bug" is founded on the solution of one of Captain Kidd's cryptograms. One can readily construct a cipher requiring considerable effort to read. One of the best known for common purposes is the "Dial Cryptogram."
A DIAL CRYPTOGRAM.
On a six-inch square of card-board draw a circle containing twenty-seven parts. In each write one of the capital letters of the alphabet, including &. Also cut out a circle of card-board which exactly fits the circle on the square. It should be edged by twenty-seven spaces containing the small letters of the alphabet, including &. Place this disk on the square and drive a pin through the centre. Your correspondent having a similar dial, you are ready to write. Suppose your message is the following:
The box containing the famous Marston-Endive ciphers has at last been found in a secret drawer of the billiard-room wainscoting. Yours, Kelpee.
At the beginning you write the capital, and at the end the small letters which are opposite each other when you have arranged your dial. The inner circle is so placed, say, that T and m are opposite each other. Beginning your message with T, and closing with m you would have:
T. may vhq whgmubgbg& may zufhnl fuklmhg-ygxboy wbiaykl aul um eulm vyyg zhngx bg u lywkym xkupyp hz may vbeebukx-khhf pubglwhmbg&. rhnkl dyeiyy. m.
The stencil cryptogram is also a very good one, and is easily managed. Take two squares of paste-board, and at irregular intervals cut out narrow openings. Your correspondent being provided with one of the stencils, you place your own on a sheet of paper, and in the openings write your message. You then fill the intermediate spaces with any words that will connect the whole and make sense. Your correspondent places his stencil on the message—and the meaning is clear.
Vincent V. M. Beede.