190 
Miscellanea 
The measured capacities of these German skulls have a mean value of 1503 c.c. a result 
which is in very close agreement with (4) the formula based on 110 skulls. 1503 is the mean 
65 
capacity of 100 skulls so that -r= = 6'5. Thus the difference between the actucil mean capacity 
SI 71 
of German skulls and the mean capacity estimated by the negro formula is less than 10 cm^. 
although the mean capacity of German male skulls exceeds that of negi'o males by 
1503-1375 = 128 cmS. 
If the above values of Z, H arc substituted in Lee and Pearson's formula (/') on p. 4 
we obtain (7=1492. 
On the other hand if we substitute the mean values of the dimensions of the 110 male negro 
skulls, B=IZ1, Z = 178, //=135 in formula P we obtain C=1400 as compared with the measured 
mean of 1375. 
This is not as good a i-eeonstruction as our formula (4) or as the formulae of Lee and Pearson 
employing auricular height, and is probably due to the fact that P is obtained by the method of 
least squares from 11 means only. 
§ 4. An approximation to the influence of the thickness of the bone of the skull on pre- 
dictious of capacity from external measurements can be obtained liy differentiating the equation 
and putting dB = dL = dH= t. 
We obtain dC = l {BL-^LH+ HB) t, 
or if we observe that in the equations the constant is comparatively small 
dC 
with i?= 150-5, Z= 180-6, ^=133-8 
dC 
1500^ 
= i!('02) api>roximatel\ 
Thus a difference of 10 cm', in capacity corresponds to a difference of A mm. in thickness 
which is about 5 of the thickness (say 6 mm.) of the human skull. 
We ma}' fairly conclude then, that there is no appreciable difference in the thickness of the 
negro skull as compared with the European. 
§ 4. The female crania yield very similar results. The following is the table for the female 
skulls. 
TABLE II. 
Mean capacity 
in cm. 3 
Mean BLH 
in cm. 3 
(Tp in cm.^ 
cm.-' 
T 
' C, BLH 
21 Congo Skulls ... 
1206 
2858 
107-7 
268-2 
-9077 
43 Gaboon (1864) ... 
1232 
2924 
126-7 
270-95 
•8814 
17 Gaboon (1880) ... 
1240 
2964 
97-31 
265-8 
-8560 
81 Negro skulls 
1227 
2956 
117 
255-72 
-7668 
