164 



Dr. E. W. A. Walker. 



is a more complicated matter and concerns the weights. These are not 

 true body-weights, but include the weight of a portion of the clothes, only 

 the coat and boots having been removed in each case before weighing. 



In order to arrive if possible at a reliable correction for the weight of 

 this portion of clothing I obtained the weights clothed (partially) and 

 unclothed, as well as other measurements, of 30 undergraduates who 

 happened to be my pupils at the moment. These 30 men are grouped 

 according to weight in Table V. From the average body-weight (part 

 clothed) and the average weights of the part-clothes for the groups a formula 

 for part-clothes was arrived at in the form c = 69"63 ^- u - 29 . This formula 

 fits excellently, the average percentage difference between c calculated by 

 this formula and c observed being only 0'50 per cent., and the mean 

 deviation by the method of least squares 0"61 per cent. 



As a further check for the part-clothes their weight was also expressed 

 (see Table V) in percentage of the corresponding body-weight (partly clothed) 

 and the percentage of body-weight (partly clothed) to be assigned to clothes 

 for each group in Table III and Table IV was estimated by interpolation 

 and extrapolation from this series. The values thus obtained were found to 

 agree very satisfactorily with the weights for clothes calculated for the 

 groups in these two Tables by the part-clothes formula. The latter were 

 therefore employed in the Tables in question in order to arrive at the true 

 (unclothed) body-weight for each group. 



But the groups in Tables III and IV are not in any case groups which 

 can be expected to exhibit the normal average relation between body-weight 

 and body-length. They cannot be employed as groups in the calculation of 

 a formula for the relationship between these measurements as growth 

 proceeds, in the way in which the groups for boys have already been used, 

 for this reason, that they represent a body of individuals measured at a 

 particular age. They constitute a selected material, being all University 

 freshmen of an age somewhere between 18 and 20 years, probably for the 

 most part between 18 and 19 years, at the time of observation. Thus the 

 heavier groups do not represent a further stage of growth of the lighter 

 groups. But the whole material simply illustrates the range of measure- 

 ment from little men to big men at a given age. Hence they differ from 

 a natural growth series by lacking from the groups at the lighter end 

 adolescent boys' over 50,000 grm. in weight — say from 15 to 18 years 

 of age — whose inclusion would diminish the average values of I in the 

 lower groups. And they lack at the heavier end all more fully-grown 

 young men of 20 years of age and upwards, whose inclusion would increase 

 the average values of I in the upper groups. 



