78 HENRY H. DONALDSON 
the foramen magnum, the right hand was gently struck three 
times against the left. This was done to pack any shot which 
might have been caught on irregularities within the cranium.° 
The cranium was then transferred to the left hand again and 
held as before while more shot were poured in. These were 
packed with a small spatula and finally pressed down with the 
forefinger of the right hand. ‘The filling was such that the shot 
was slightly heaped in the center of the foramen so as to rise a 
little above the level of its edge. When thus filled, each cranium 
was placed vertically, nose down, in a small weighing bottle, so 
that no shot should be lost through accidental jarring. 
The filled cranium was next weighed to the tenth of a milli- 
gram and the weight of the shot computed by subtracting from 
the weight of the filled cranium the weight of the empty cranium 
as previously determined. The cranium was then emptied and 
again filled and weighed, and if the two weights of the shot were 
within one per cent of one another, they were deemed satisfac- 
tory. In 84 per cent of the cases two weighings only were neces- 
sary. When the discrepancy was greater than 1 per cent in the 
first instance, and more than two weighings were required, the | 
two determinations in closest agreement were selected for aver- 
aging, and the number thus obtained was that recorded. In this 
connection it may be noted that in the nine series of crania meas- 
ured in the course of this investigation, the mean difference be- 
tween the two weighings of shot which were used as the basis for 
the averages, was 0.6 per cent. This corresponds to a mean dif- 
ference of from three to five shot according to the total weight of 
the shot required to fill the cranium. 
3 As serving to illustrate the pitfalls besetting the determination of cranial 
capacity by the use of shot, I may call attention to the fact that when a container 
has been filled, it does not always follow that any disturbance of the contained 
shot will decrease its volume. For example: if a glass measuring cylinder gradua- 
uated to hold 10 ce. and having an internal diameter of 1 cm. is exactly filled to the 
upper limit of the graduation with number 11 shot, poured into it in a steady 
stream, so that the filling requires about fifteen seconds, and then the mouth of 
the cylinder is closed with the thumb and the cylinder once inverted, the shot hav- 
ing a run within the cylinder of about 5 em., it is found that the volume of the 
shot is increased by this treatment about 0.5 cc. or 5 per cent. If the cylinder be 
now gently tapped on the bottom eight or ten times, the volume of the shot again 
diminishes to its original value. 
