This is a Keaton music typewriter, circa 1936. It was used to produce much larger quantities of sheet music than could be produced by hand at the time.
If you google “music typewriter” there are videos of this same model being used.
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Helena. Girl in her(roaring)thirties; half spanish, half greek. Jazz, silent cinema and 20s and 60s lover, dreaming with a modern flapper´s world. Sometimes, my posts have been written both in English and Spanish because I love to write in my own...