5. Development of mean relative sitting height, American females. This is calculated by dividing the sitting height by the stature. The result may be plotted as percentage of the stature, as indicated on diagram.
6. Development of mean absolute span or arm. The subject stands against a broad, unbroken wall, touches the tip of the middle finger to a corner of the room and stretches the tip of the other finger to its utmost limit while retaining contact of the finger of the opposite hand with the corner. The distance to the tip of the outstretched finger is to be marked on the wall and the horizontal distance from the point to the corner of the room is to be measured twice and the more accurate measurement, or the average of both is to be taken.
7. Development of chest girth. The chest girth is taken by placing a tape around the chest under the arm-pits, below the tips of the scapulae behind and just above the nipples or breasts in front. The measurement should be taken over as little clothing as possible; if practical, in contact with the skin, as the standard of the chart is from skin measurements. The measurement is to be taken with the chest in repose; half way between the extremes of measurement when the subject is breathing quietly; arms hanging loosely by the sides. This dimension is extremely important because of the close relation between small chest girth and lung tuberculosis, and between large chest girth and resistance to disease.
8. Development of relative chest girth. The chest girth as plotted on Chart 7 for any month of age is to be divided by the stature recorded for that same month in Chart 1.
Acknowledgment is made of the co-operation of a committee appointed by the American Anthropological Association consisting of Drs. Clark Wissler, E. A. Hooton, and C. B. Davenport. The last named is grateful for the helpful criticism of the rest of the committee, but assumes full responsibility for the curves presented. The curves of the means were first drawn from available sources by his assistant, Miss Anne W. March; the standard deviations were calculated by Miss March, and the calculations checked by others.