Here's some vocabulary you may need to understand the passage on the next page:

cipher - noun: A note written in a secret code.

 

telegraph - noun: A device used to send a message at a distance over a wire (usually in Morse code).

 

message - noun: A note to a person, usually brief and written.

 

key - noun: Something important for explaining.

 

variation - noun: Something changed a little bit.

 

cryptography - noun: The act of writing in code or cipher.