galton.org 33
Statistical Methods
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practices to be a treason to his aesthetic nature. Consequently few of the
original stock of Quakers are likely to have had the temperament that is
associated with a love for colour, and it is in consequence most reasonable
to believe that a larger proportion of colour-blind men would have been
found among them than among the rest of the population.
Again, Quakerism is a decreasing sect, weakened by yearly desertions
and losses, especially as the act of marriage with a person who is not a
member of the Society is necessarily followed by exclusion from it. It is
most probable that a large proportion of the deserters would be those who,
through reversion to some bygone ancestor, had sufficient artistic taste to
make a continuance of Quaker practices too irksome to be endured. Hence
the existing members of the Society of Friends are a race who probably
contained in the first instance an unduly large proportion of colour-blind
men, and from whose descendants many of those who were not born
colour blind have year by year been drafted away. Both causes must have
combined with the already well-known tendency of colour blindness to
hereditary transmission, to cause it to become a characteristic of their
race. Dalton, who first discovered its existence as a personal peculiarity of
his own, was a Quaker to his death; Young, the discoverer of the
undulatory theory of light, and who wrote specially on colours, was a
Quaker by birth, but he married outside the body and so ceased to belong
to it.
STATISTICAL METHODS.
The object of statistical science is to discover methods of condensing
information concerning large groups of allied facts into brief and
compendious expressions suitable for discussion. The possibility of doing
this is based on the constancy and continuity with which objects of the
same species are found to vary. That is to say, we always find, after
sorting any large number of such objects in the order 4 let us suppose) of
their lengths, beginning with the shortest and ending with the tallest, and
setting them side by
