2. The device of claim 1 including two additional rotatable members mounted to said support member and bearing additional alphabetical symbols for display at the display window by rotation of said additional alphabetical symbols, and wherein said two additional rotatable members are mounted with respect to said support member such that the axes thereof and the axis of said first rotatable member form a triangle with a peripheral portion of one of said additional rotatable members protruding from one side edge of said support member and with a peripheral portion of the other of said additional rotatable members protruding from another side edge of said support member to enable rotation of said additional rotatable members to be effected by manual manipulation of said protruding peripheral portions of said additional rotatable members.
2. The device of claim 1 including two additional rotatable members mounted to said support member and bearing additional alphabetical symbols for display at the display window by rotation of said additional alphabetical symbols, and wherein said two additional rotatable members are mounted with respect to said support member such that the axes thereof and the axis of said first rotatable member form a triangle with a peripheral portion of one of said additional rotatable members protruding from one side edge of said support member and with a peripheral portion of the other of said additional rotatable members protruding from another side edge of said support member to enable rotation of said additional rotatable members to be effected by manual manipulation of said protruding peripheral portions of said additional rotatable members. 3. The device of claim 2 wherein the alphabetical symbols on each of said second and third rotatable members and each of said additional rotatable members comprise single consonant letters, silent letters and blanks.