229 
with the lightest. Note the number who fail and the number 
who succeed in each test, and that is alb But it is safer to 
use three test-stones as a check upon the calculation. Also, 
before finally selecting the stones, make a few preliminary 
trials and fix upon such as it is likely that, roughly, about a 
quarter of the whole number would fail with the first, half 
with the second, and three-quarters with the third. It is 
impossible, briefly, to explain how the calculations have to be 
made. The method is fully described in my work on 
“ Natural Inheritance,” p. 62 (Macmillan & Co., 1889). 
F. G. 
No. LXXIIL—POPULATION. 
Count wherever you can. The contingents of fighting-men 
afforded by a district, as compared with that procurable from 
other districts, gives some idea of their relative population, 
and it is not difficult to make out the particulars of a small 
district in detail. In some countries the numbers attending 
a religious festival may give a clue, so may the number of 
marriage-feasts and burials, 
F. G. 
No. LXXIV.—CONTACT WITH CIVILIZED 
RACES. 
1. Were the first civilized strangers who visited the races 
reported on, sailors, traders, refugees, convicts, deserters, 
settlers, or missionaries ? 
2. Did they communicate the vices rather than the virtues 
of civilized life ? 
3. What was the influence of the missionaries ? Did they 
impart religious instruction only ? Was the conversion of the 
