This simple device has a distinguished history. Ever since its first invention it has been repeatedly re-invented in forms only slightly different from the original. Its story shows that man has sought to put the wheel to use i secret communicationswherever n possible, even as he also does in mechanics, As invented in Italy sometime before 1470, it had similar concentric disks with the exception that one contained a "mixed" (scrambled) alphabet Also, in some of the earlierversions, one of the two alphabets