30 OBSERVATIONS AND MEASUREMENTS ACADEMY MEMBERS 



[Memoirs National 

 [Vol. XXIII, 



The Three Main Diameters of the Head 



HEAD LENGTH 2i 



The length, breadth, and height of the cranial vault correlate directly and compensate 

 with each other, and the full values of the individual measurements could only be found in 

 racially pure groups. We have no such group in the Academy, but that of the members of old 

 American descent presents a limitedly mixed group which is fairly comparable with that of the 

 subjects of similar derivation outside. The conditions, so far as head length is concerned, are 

 as follows: 



Table 26. — Head length 



Members of the Academy 



Old Americans 



Not old Americans 



Old Americans 

 at large (total 

 series, except 

 mountaineers) 



Subjects 



Average 



Minimum 



Maximum 



Range of variation in percentage of the average _ 



CV. 



100 



19. 94 ±0.043 



18. 3 



21. 5 



16. 05 



0. 635 ±0. 030 



3. 18±0. 15 



50 



19. 82 ±0. 055 



18. 7 



21. 



11. 60 



0. 580 ±0. 039 



2. 92 ±0. 20 



594 



19.76 



18.0 



21. 6 



IS. 22 



DISTRIBUTION 



Centimeters . 



Old Americans (100) 



Not old Americans (50) . 



18.3-18.7 18.8-19.2 19.3-19.7 19.8-20.2 20.3-20.7 20.8-21.2 21.3-21.5 



Percent 



2 

 2 



Percent 



16 



Percent 



29 

 24 



Percent 

 30 

 32 



Percent 

 19 

 22 



Percent 



9 



4 



Percent 

 3 



■ In the laboratory series of 247-19. 79. 



Not much needs to be said in this place as to the above figures. They are not far apart in 

 the three groups, yet the outsiders give a smaller value and that especially as compared with 

 the academicians of similar derivation. The true value of these differences can only be appraised 

 in conjunction with those of the two other main head measurements. The range of individual 

 variation follows naturally the size of the groups. The distribution of the measurement is 

 fairly regular. 



HEAD BREADTH 



The essentials concerning this measurement are given in the next table, 

 dimension, taken separately, is as already mentioned quite limited. 



The value of the 



u The greatest obtainable length between the glabella and the most distal normal point on the occiput, whatever its location. For directions 

 of technique see the writer's Anthropometry. 



