496 HEIGHT AND WEIGHT IN RELATION TO BUILD 



graphs taken with the body in definite postures. The constant which he used to 

 estimate body surface from silhouette area is based on the Du Bois observations on 

 surface-area. The Benedict method has the great advantage of furnishing useful 

 records of body shape. 



Neither of the methods mentioned are based on data concerning volume or on 

 weight as an index of volume. On the other hand, Meeh (1879), to whom we are 

 still indebted for the most extensive series yet made of careful observations of 

 surface-area of normal individuals during growth, proposed a method of estimating 

 surface from weight by the use of the formula S = KW 2/3 , in which $ = area, W = 

 weight, and K is a constant based on Meeh's observed data. The disadvantage of 

 this method lies in the fact that it can apply with a given constant only so far 

 as the individuals whose surface is estimated are similar in shape. For infants K 

 is smaller than for adults. Several methods have been proposed for lessening the 

 disadvantage mentioned by means of the use of various linear measurements in 

 constructing a formula for estimating surface. For a brief review of these methods 

 the reader is referred to Du Bois and Du Bois (1915). None has proved to be of 

 much practical value. 



Of the linear measurements of the body, stature in relation to weight gives us, 

 as we have seen, the most practical simple index of shape. For estimating surface- 

 area, therefore, it is of value to use the ratio between observed surface-area and the 

 surface of an object which has the same length as the stature of the body and a 

 volume which may be estimated from body-weight. For the purpose proposed it 

 is simplest to assume a specific gravity of 1.000 if we are dealing with metric-system 

 units or of 1.0252 if we are dealing with inch-pound units. In the former case we 

 divide the weight in grams by the height in centimeters. The quotient gives us the 

 average cross-section in square centimeters of an object as long as the body and of 

 the same volume. This elongated object may be conceived either as circular or 

 as square in cross-section. In the latter case the surface of the object is larger 

 than in the former. If we assume the object to be a flattened block, as we have in 

 considering volume, the surface becomes still larger. I have chosen the block with 

 a square cross-section as the simplest object for our present purpose. The formula 

 for surface-area thus becomes : 



W 



where S = surface-area, W is weight in grams, H height in centimeters, and K is a 



constant. In the formula ~ gives the surface-area of each end of the block, H K 



H \ H 



the surface-area of one side of the block. K has to be determined from the ob- 

 served surface-area of individuals of given height and weight. If inch-pound 

 units are used, one must substitute WX27.68 for W in the formula given above if 

 the same specific gravity is assumed as in this formula, or JFX27 if one assumes the 

 same specific gravity I have assumed in dealing with volume. 



The value of K depends on the data one chooses as representing the most 

 accurate observations on surface-area. The best observations appear to be those 



