From: US Naval Air Development Center, Document NADC-MR-6516, “Post-flight chest discomfort in aviators: aero-atelectasis”, by Elihu York, page 3, 12/30/1965. The McKesson Vitalor was a dry wedge bellows spirometer. A pen attached to the top of the bellows marked on a small sheet of graph paper that was attached to an electric motor-driven platen. In this picture the subject is exhaling directly into the mouthpiece that was permanently attached to the front of the spirometer.
From: JAMA, 1961 Sep 23. Volume 177, page 865. A dry wedge bellows spirometer. A pen attached to the lid of the bellows wrote on a small sheet of graph paper that was driven horizontally by an electric motor during exhalation.
From: Basal Metabolism: Its determination and Application. FB Sanborn. Page 123. Published 1922. Variation of a Krogh Spirometer. Described in text as being 17 inches high and weighing 40 pounds.