What you need
The printed template
Card
Scissors
A split pin
How to build it
Build it like the wheelGlue to card, cut out both circles, pin them together through the middle.
Notice the inner ringIt is not the alphabet in order. It is scrambled, and that alone makes it stronger than Caesar.
Agree a starting letterLine the inner A up with an agreed outer letter and begin.
Now turn it mid-messageEvery few words, move the inner ring one place on. Write a capital in your message to show where you turned it.
Send the letter and the ruleYour friend needs the starting letter and the rule for turning, and nothing else.
Turning the disk is the whole invention. A wheel you never turn is only a Caesar shift with extra steps.
The template
Print this at 100 per cent, not fit to page, or the sizes will be wrong. The ruler line below tells you whether it printed correctly.
The bar above should measure exactly 10 centimetres. If it does not, your printer has shrunk the page.
Now send something
Write a message and turn the disk after every fifth letter. Then count how many times the letter E came out as something different.
Lewis Carroll’s tableBack to Make