From Jahrbücher der in- und ausländischen gesammten Medizin, Volume 67, Published Wigand, 1850, page 43. A water-sealed gas meter.
From Handbuch der speciellen Pathologie und Therapie, Volume 5, Part 1, by Rudolf Ludwig Karl Virchow. Published by F. Enke, 1854, page 106.
Spirometer attributed to Franz Forstmann and is a wet (water sealed) gas meter.
The diverse, quirky and mostly forgotten history of Pulmonary Function testing