Sliding Scale or Cryptograph

Slide the alphabet along by a certain number of letters, e.g. 1 letter:

Plain text: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Code: B C D E F G H I J K L M N O P Q R S T U V W X Y Z A

Example:

SCOUT = TDPVU

Here's a code for you to solve:

NFFU NF JO UIF QBSL CZ NPPOMJHIU

Cryptograph Wheel

You can make a special Cryptograph Wheel to solve cryptographs (see the picture!) First make two circles of cardboard, one a bit smaller than the other, and use a protractor to mark them off into 26 pieces of about 13.8 degrees each. Write one letter of the alphabet in each division on each wheel.

Then attach the two wheels together using a split pin so that you can rotate them independently.

Now if you want to solve a cryptograph where the alphabet slides along by 3 places, just rotate the wheel so that A is opposite the C, and then you can read the code letters off the wheel.

The Cryptograph Wheel below was published in 1869. It is slightly more complicated than ours, because the letters are in a random order.

(Public domain image from Wikipedia)