48 First Results from the Oxford Anthropometric Laboratory 
Two cranial indices are deduced from these measurements, namely, the ratio 
of the greatest breadth to the greatest length, and of the auricular height to the 
greatest length. 
A Flower's Cranimeter was used for measuring the greatest length and the 
greatest breadth, while the auricular height was taken with a special instrument not 
hitherto described. 
This instrument consists essentially of a long brass box with open ends which 
forms a bearing for two flat bars. The bars can slide in or out of the box in the 
direction of its longitudinal axis, but they are constrained to move inwards or 
outwards to an equal extent as they each carry, where they face one another in 
the box, a rack which is in mesh with one and the same pinion. Running down- 
wards from the outer ends of the bars and at right angles to them are long arms, 
to the lower ends of which are attached the ear points. Sliding through bearings 
in the top and bottom of the box is a round rod, which is brought down on to the 
top of the subject's head, on it is engraved a scale by which the distance from the 
top of the head to the line joining the ear points may be arrived at. The object 
of the two racks and the pinion is to ensure that the end of the rod comes down 
on to the middle line of the head. This instrument is too heavy to be held in 
the hand of the operator in the usual way and therefore is suspended from 
a sort of double gallows and counterpoised. 
The numbers available are not sufficient to enable me to make any very 
definite statement about the changes in head measurements with age, but there 
is some indication that the length increases during the period dealt with. The 
mean head length at 18 is 195 2 mm., at 21 196 05, and at 27 197*4 mm. The 
breadth for these ages 152 - 9, 152 - 7, 153"1, respectively, while the highest mean 
head breadth recorded is, at 22, namely 153"66, so that this measurement shows 
little if any increase. Consequently the cranial index (breadth to length) drops 
slightly, being 78'40 for the youngest group, at 77"59 for the oldest. The auricular 
height shows a very slight tendency to rise, while its index falls slightly. The 
correlation between stature and head length is "31, which is more than twice as 
great as that between stature and head breadth ('14). Consequently there is a 
slight negative correlation between this and the cranial index BjL. (—"13.) 
The correlation between stature and auricular height is about the same as 
that between stature and head length, and therefore the auricular height index 
shows itself as practically independent of stature. 
