Attributed to Petzold, Wilhelm. 1891. Preis-Verzeichniss der Werkstätte für Präcisions-Mechanik von Wilh. Petzold: Abtheilung der Instrumente und Apparate für physiologische Experimente und Vivisectionen. (p. 0029, fig. 97)
Taken from: The Development of Methods for Determining Basal Metabolism of Mankind Carpenter, Thorne M. The Ohio Journal of Science. v33 n5 (September, 1933), 297-314
Knipping Spirometer, circa 1950’s. Found in an on-line brochure for the Museum of the Department of Physiology, Colombo Medical School. Authors Dr. A.K. Vidanapathirana, Dr. P.M. Attapattu, Ms. Nadeetha keragala.