1 30 Biometric Constants of English Brain-iveights 
TABLE VIII. Variability of Head Measurements. 
Group 
Length 
Breadth 
Auricular Height 
S. D. 
C. of V. 
S. D. 
C. of V. 
S. D. 
C. of V. 
? 
6 
? 
6 
? 
6 
? 
6 
? 
6 
? 
General Hospital Population 
English Criuiinal.s* 
Cambridge Graduates f 
5- 62 
6- 05 
6-16 
5-59 
2- 95 
3- 15 
3-18 
3-05 
5-41 
5-01 
5-06 
5-76 
3-62 
3-33 
3-28 
3-99 
4-51 
4-35 
3-39 
3-37 
English Skulls 
6-27 
6-22 
3-31 
3-45 
5-28 
4-77 
3-75 
3-54 
4-28 
4-50 
3-73 
4-12 
Very little of a definite kind can be deduced from these rather sparse results. 
In length the general hospital population seems less variable than either the 
English criminals or Cambridge graduates, but it is more variable in breadth. If 
we compare the variability of the diameters of the living head with those of the 
skull, we see that the head is clearly not definitely more variable than the skull, and 
accordingly the assumption often made that owing to the presence of the flesh it 
must be so, is erroneous. The paradox is explicable on the basis of a negative 
correlation between skull diameters and amount of covering fleshj, i.e., individuals 
growing much bone must on the avei-age have less flesh. 
Taking next cephalic index we have for English groups : 
TABLE Ylllbis. 
Group 
Cephalic Index 
Standard Deviation 
Coefficient of Variation 
6 
? 
6 
? 
General Hospital Population 
2-76 
2-87 
3-52 
3-64 
English Criminals § 
2-74 
3-55 
Cambridge Graduates j| ... 
2-90 
3-70 
School Children IT 
3-31 
3-99 
4-20 
5-09 
British Association** 
2-52 
2-96 
3-24 
3-76 
English Skulls tt 
3-26 
2-98 
4-38 
3-99 
* Macdonell : Biomelrika, Vol. i. p. 202. t Fawcett : R. S. Proc. 
X Let (T; be s.d. of skull length, (Tl, of head length, a-/ of flesh thickness ; then : 
a-L = { 0-;'' + 0-/ + 2(ri <Tf i-fi ] h 
or at must be greater than a-; unless »•/;, the correlation between amount of flesh and bone size, be 
negative. 
§ Macdonell: Biometrika, Vol. i. p. 191. || Idem, p. 191. 
Tl Pearson : Biometrika, Vol. in. p. 140. ** Pearson : The Chances of Death, Vol. i. p. 351. 
tt Macdonell : Biometrika, Vol. m. p. 222. 
