Since the invention of the spirometer by John Hutchinson1 in 1846, many valuable observations have been made by him and numerous other investigators on the vital capacity of the lungs in normal persons, as well as in those suffering from disease.
I shall not give a complete review of the literature on this subject, but references to certain important and closely related contributions will be given.
It is now an accepted fact that the vital capacity of a person is reduced in certain diseased conditions of the lungs, pleura and heart. The observations of Myers,2 Garvin, Lundsgaard and Van Slyke,3 Ulrich and Nathanson,4 Wittich, Myers and Jennings,5 Peabody and Wentworth,6 Dreyer and Burrell7 and others have shown that there is a definite relation between the vital capacity of the lungs and the amount and type of the pathologic condition of the thoracic organs. Their studies also show that the vital