The Talking Machine Patent Archive

Patents you could hear

Electromagnet armature

Front elevation of an upright piano case with three paneled windows above the keyboard, a small pointer and dial labeled O and P near the treble end of the keys, three pedals below, and accompanying schematic diagrams of the electric circuit, perforated control strip, and circuit-closer mechanism beneath the main drawing.EXPRESSION-INDICATOR FOR SELF-PLAYING INSTRUMENTSFrederick W. Hedgeland · November 19, 1895