 According to Grove Music Online (2007) article on "Duplex Scaling", Steinway progressed a system of aliquot scaling to provide sympathetic resonance with the intention of enriching the treble register of the piano.In the 'octave duplex' piano by Hoerr of Toronto, each note had four strings, of which two, three or four could potentially be struck by the hammer depending on the depression of one of four pedals.Steinway’s duplex scale was precipitated a half century earlier by an experiment conducted by the German piano maker Wilhelm Leberecht Petzoldt, in which a small bridge was placed behind the standard larger one with the intention of maximizing the potential additional resonance of a sympathetically vibrating additional length of string.