The vital capacity of the lungs is the expression applied to the volume of air that can be expired after the deepest possible inspiration. Among the factors affecting the vital capacity are the age, sex, height, weight, the size and flexibility of the thorax, and the state of physical training of the individual. Recent measurements made at the medical clinic of the Peter Bent Brigham Hospital in Boston furnish the following standards for the vital capacity of the lungs of normal men: for men over 6 feet tall, 5,100 c.c.; between 5 feet 8½ inches and 6 feet, 4,800 c.c.; between 5 feet 3 inches and 5 feet 8½ inches, 4,000 c.c. In women of the same heights it is about one fifth less. When compared with these standards, the vital capacity of healthy persons very rarely falls below 90 per cent, of the normal standard, although it may rise