In spite of being slow to use, the Mignon was immensely popular and survived until the 1940s. It was invented in 1903 by Dr Friedrich von Hefner-Alteneck and made by the electrical company aeG. A metal type-sleeve shifts and rotates in response to the movements of a pointer over an index tablet marked with the letters of the alphabet. When the required letter has been selected, a single key is presed to make the impresion. A second key gives spaces. The type sleeve and index are instantly interchangable for different character sets.
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