_Observer._ _Place._ _No. of _Average Age._
Cases._
Ravn Copenhagen 3,840 16 years, 9 months.
Frugel Christiania 157 16 years, 6 months.
Dubois Russia 600 16 years, 8 months.
Faye Norway 100 15 years, 6 months.
Lundborg Esquimaux 16 15 years, 6 months.
Wistrand Stockholm 100 15 years, 7 months.
from these observations we obtain an average of 16 years and 3 months.