Historical Technology Books - 74 in a series - Cipher and secret letter and telegraph code, with Hogg's improvements (1884)
This Secret Code may be used by any oue. It is so perfect that no message written by it can possibly be read without knowing the particular keyword us3d. In most of the Cipher systems a mere changing of the order of the alphabet, or certain signs for certain letters, has been used, and in consequence of the same letter being always represented by the same cipher, an expert could easily read any message. In this system the constant change ot cipher for every letter makes the message perfectly secret. By its use any number of persons may write the same message, and each be unintelligible save for those intended. It is very simple, and with ordinary care there can be no mistake or misunderstanding. Your message can be written in any language.