The Polygraph was a German-made schreibmaschine (typewriter) whose inventor was Paul Riesner. Three models were produced of the typewriter, a curved-keyboard No.1 and straight-keyboard Nos. 2 & 3, by Polyphon Musik-Werke of Wahren, Leipzig. All of the models are quite desirable and I would be very interested in any.
Have one for sale? Please email me at Antikey.Chop@gmail.com