A CRITIQUE OF THE BODY-SURFACE LAW. 



157 



find a correlation of unity. For any given weight (or surface) there 

 would then be only one possible heat-production. But as a matter of 

 fact the coefficient of correlation, here being less than unity, shows that 

 for any given body-weight or body-surface a variety of heat constants 

 may be secured. How widely the heat-productions of individuals of 

 sensibly identical body-weight may vary is well shown by diagram 23 

 for men and diagram 24 for women, in which each dot represents on 



BODY SURFACE 



DIAGRAM 26. Relationship between total heat-production and square meters of 

 body-surface of men as estimated by the Du Bois height-weight chart. 



the scale at the left the heat-production of an individual whose weight 

 is given by the lower scale. 73 That body-surface is not much better 

 than body-weight as a basis for prediction is evident from the wide 

 scatter of the heat-productions for individuals of like superficial area 

 in diagrams 25 and 26. 



Now it is quite possible to determine from the correlation coefficient 

 approximately the amount of variation which will be found on the 

 average within the different weight or body-surface classes. This 



73 The straight lines in these diagrams are drawn from the equations in Chapter IV, p. 91. 



