From H. Brodard Medical and Surgical Instruments Catalog No. 10, 1934, page 52. Described as a spirometer from the design of R.B.S., 7 liters. At a guess it is a gas meter type.
From H. Brodard Medical and Surgical Instruments Catalog No. 10, 1934, page 52. Described as a spirometer from the design of R.B.S., 7 liters. At a guess it is a gas meter type.