BEPORT OF THE ANTHROPOMETRIC COMMITTEE. 233 



APPENDIX. 



Mr. C. Roberts, ivho has prepared the Tables from I. to VII. for the 

 Committee, has contributed the following explanations and remarJcs : — 



Tables I. (height), II. (weight), III. (chest-girth), and IV. (strength), 

 are intended to show the chief physical characters of the British race : 

 hence the whole number of observations are given to show the range or 

 variation of the stature, weight, &c., at each age, and the relative number 

 of individuals at each height, weight, &c. ; the mean height, chest-girth, 

 weight, and strength being indicated by the horizontal lines crossing the 

 columns of figures where the largest number of observations occur. 



Tables V. and VI. show the average stature and weight of different 

 classes of the nation, — classes which have been differentiated by social or 

 sanitary surroundings and peculiar occupations. 



It is necessary to call attention to the difference between the average 

 and the mean as employed in these tables. An average is obtained by 

 dividing the sum of the values observed by the number of observations, 

 while the mean is the value at which the largest number of observations 

 occur (' the value of greatest frequency.') An average is influenced by 

 exceptional cases, but a mean disregards exceptional cases and is entirely 

 dependent on the predominating numbers ; hence I have employed the 

 mean to distinguish the racial type, and the average the variations to 

 which the race is subject by the modifying influences of local and excep- 

 tional causes. To determine the racial type of a nation by means of an 

 average it would be necessary to have all classes of the community 

 represented in their due proportions ; but the unequal distribution of 

 occupations renders this impossible, unless a general census were taken. 

 Even within narrow limits it is almost impossible to obtain observations 

 of all the individuals of a class, as the taller and better-developed members 

 readily submit to measurement, while the shorter and imperfectly- de- 

 veloped evade examination, and the sick and deformed are passed over 

 altogether. On the other hand, the determination of the racial type by 

 the mean is free from these sources of error, as we disregard both the ill- 

 developed and the over-developed individuals, and depend entirely on 

 those which represent the medium development of the class or nation. 

 Table VII., giving the stature of adult men of different classes of the 

 British population shows the difference between the average and the 

 mean. In those classes, where all the individuals have been accessible 

 and no selection has been attempted, the average and the mean stature 

 are almost identical ; but in the case of the recruits for the army, where 

 all the men below a certain standard are excluded, the average is an inch 

 higher than the mean stature. The average in this case implies that 

 recruits are of the same type as the agricultural classes (Class III.), but 

 the mean shows that they are really of the type of the town artisan 

 class (Class IV.) from which we know they are chiefly drawn. This 

 also explains why the average stature of the general population (Table V.) 

 J8 half an inch higher than the mean stature (Treble I.) 



