During a recent investigation of "The Relation of Chest Contours to Lung Capacity," made by Dr. F. F. Malone,1 in the physiologic laboratory of the Northwestern University Medical School, it occurred to me, first, that there should be a method of computing area expansion from the diameters; and second, that there should be a method of computing lung capacity from area expansion and thoracic length.
The chest contours were traced through the help of the chest pantograph, which I devised.2 One of these contours is shown in Figure 1. The one chosen for this figure happens to represent a chest of unusually high index, i. e., an unusually deep chest. The inner line shows the contour of the chest at the end of the forced expiration, while the outer line gives the contour at the end of the forced inspiration.
The cross-sectional area or contour area of the chest at