"Merely reverse the process. You write down the cypher message, and above it as many letters of your key-word as may be needed, thus:"
| B | E | A | D | B | E | A | ||
| E | F | C | J | G | J | E |
"Now follow down the vertical column headed by B until you reach the symbol letter E; then move your pointer over left to the end of that horizontal line which will give you C, the first letter of the original message. Understand?"
Betty tried her hand, and quickly caught the trick; really it was very easy.
"One more point; it is better not to divide the cypher message into word groups as the continuous string of letters looks more mystifying. There is no difficulty in picking out the sense when decoding."
"Finally, you notice that the upper left-hand space in the diagram is vacant; consequently you must not use the letter Z in either the key-word or in the message to be coded. But this restriction is not of any practical disadvantage, Z being a letter that is seldom used. It will often appear, of course, in the cypher itself."
"Certainly it is all very simple," remarked Betty.
"But without the key-word where would you get off?"
"I don't see how anybody could possibly work it out; why the complications are absolutely overwhelming."
"And you can make them still more intricate by merely using a longer key-word, or indeed a whole sentence. For example: 'I love Betty Hildebrand.'"