Driesen, Otto. 1913. Das Grammophon Im Dienste Des Unterrichts Und Der Wissenschaft. Band I, Teil 1: Kindergarten, Volksschule, Mittelschule, Höhere Lehranstalten. Berlin: Deutsche Grammophon-Aktiengesellschaft.
Object, Instrument, Technology

The double siren was one of Koenig’s more popular instruments. It consisted of two “polyphonic” or “multivoiced” sirens with more than one series of holes, and was an invention of the German physicist and former teacher of Hermann von Helmholtz, Heinrich Wilhelm Dove (1803–1879). It produced several pure tones simultaneously, in musical chords, and under greater pressure. It was ideal for demonstrating interference effects (when sound waves combined to amplify or diminish each other) and combination tones. [Pantalony 2009, 184-185]


“Index: Tone-Limit Apparatus”. 2013.
Anonymous,. 1961. “Gedruckte Schaltungen Für Neuartige Fernhörer Und Zur Steuerung Von Erdsatelliten”. Die Umschau In Wissenschaft Und Technik.
Contributor essay
Paolo Brenni

The scientific instruments used for research and teaching in the nineteenth and early twentieth century are beautiful and fascinating artifacts.