On this cipher necklace the square beads represent the _a_ form, the round beads the _b_ form. The cipher words are "Yankee Doodle." For working this or any other appropriate phrase, the child should string the beads on one of the laces provided. LESSON IX [Illustration] This is similar to the preceding lesson except that in this case the blue beads represent the _a_ form, the orange beads, the _b_ form. The cipher words are "A Cipher Chain." LESSON X [Illustration] This cipher necklace combines both Lessons VIII and IX, and shows how two ciphers may be infolded at once. Reading the beads first as regards their shape and using the same system as in Lesson VIII, the necklace still spells out the word "Yankee Doodle." Then reading the beads as regards color, the words "A Cipher Chain" are deciphered, as in Lesson IX. This lesson gives a hint of the possibility of enfolding three, four, or five cipher messages at once. LESSON XI [Illustration] In this lesson comes the first step in showing how a cipher message may be hidden within an ordinary architectural example. The red circles represent the _a_ form, the blue ones the _b_ form; the reading proceeds in exactly the same way in which the figure is written. The cipher phrase is "United States." Any figures can be selected for the children to form, provided, when formed, they contain the requisite number of circles of each color. LESSON XII [Illustration] The cipher word is "pasture," the red circles being the _a_ form, the blue ones the _b_ form. LESSON XIII [Illustration] The cipher word is "Barking," the red circles being the _a_ form, the blue ones the _b_ form. LESSON XIV [Illustration] The word "CIPHER" contains the hidden name "Sir Francis Bacon," the red circles being the _a_ form, the blue ones, the _b_ form. The reading proceeds in the same manner as the strokes of the letters would be made by the hand. The design in the margin contains a double cipher, similar in construction to the necklace in Lesson X. The red and blue pieces still represent the _a_ and the _b_ forms respectively, as before, and the cipher word is "alphabet." This constitutes the first cipher. The second cipher is based upon the difference in shape of these pieces, the long ones being the _a_ form, the circles, the _b_ form. The cipher word is "decipher." LESSON XV [Illustration] The phrase "Biliteral Cipher" is made to contain the hidden word "key" by the use of a capital letter for the _a_ form, and a small letter for the _b_ form. The borders to the lines contain the cipher word "letter," the blue sticks being the _a_ form, the red ones the _b_ form. The reading proceeds from left to right in each line, beginning with the line at the top. The children may be directed to cut out any set of letters of appropriate size to form any desired phrase, using capital and small letters on the same principle as in the example. LESSON XVI