A nasal breathing valve designed by Tissot.  Used one-way valves so exhaled air could be collected and analyzed.  Included an electical switch that was activated during inspiration.  From J. Tissot, “Nouvelle méthode de mesure et d’inscription du débit et des mouvements respiratoires de l’homme et des animaux”, Journal de physiologie et de pathologie générale, 1904, vol 6, pp. 690.