Found on the Steno Museum Collections website. It’s description (translated from Danish by Google): “Vippespirometeret is of the type which August Krogh constructed in the early 1900s. This vippespirometer was purchased and used by the Department of Physiology, University of Aarhus in 1970. Here it was used in studies in climate chambers for the determination of “closing volume” that is the volume of the lung, wherein the first airway collapse during exhalation, and a measure of the airway condition. The spirometer was used for the first Danish published study using this method.” Size 81x36x40cm. Dated by the museum as manufactured by Kifa, Stockholm, Sweden in 1940 although this date may be in error. I suspect but cannot be sure that the electrical wiring is for a water heater in order to keep the spirometer at body temperature.