The process of physical growth in children is manifested by changes in their size, mass and shape. Changes in size are ascertained by measurement, usually, of the standing height of the child, but occasionally of the sitting height, and sometimes, also, of the chest circumference and the width between the hips. Changes in mass are detected by weighing, whilst changes in shape, which are due to unequal rates of growth in height and in mass, are estimated by methods referred to later.