as being gifted with powers at least equal to those of
their distinguished brothers, but definite facts in corroboration of
such estimates were rarely supplied.

The same absence of solid evidence is more or less true of gifted
youths whose scholastic successes, unless of the highest order, are a
doubtful indication of future power and performance, these depending
much on the length of time during which their minds will continue to
develop. Only a few of the Subjects of the pedigrees in the following
pages have sons in the full maturity of their powers, so it seemed
safer to exclude all relatives who were of a lower generation than
themselves from the statistical inquiry. This will therefore be
confined to the successes of fathers, brothers, grandfathers, uncles,
great-uncles, great-grandfathers, and male first cousins.

Only 207 persons out of the 467 who were addressed sent serviceable
replies, and these cannot be considered a fair sample of the whole.
Abstention might have been due to dislike of publicity, to inertia,
or to pure ignorance, none of which would have much affected the
values as a sample; but an unquestionably common motive does so
seriously--namely, when the person addressed had no noteworthy
kinsfolk to write about. On the latter ground the 260 who did not
reply would, as a whole, be poorer in noteworthy kinsmen than the 207
who did. The true percentages for the 467 lie between two limits:
the upper limit supposes the richness of the 207 to be shared by the
260; the lower limit supposes it to be concentrated in the 207, the
remaining 260 being utterly barren of it. Consequently, the upper
limit is found by multiplying the number of observations by 100 and
dividing by 207, the lower by multiplying by 100 and dividing by 467.
These limits are unreasonably wide; I cannot guess which is the more
remote from the truth, but it cannot be far removed from their mean
values, and this may be accepted as roughly approximate. The
observations and conclusions from them are given in Table VII., p. xl.

CHAPTER IX.--MARKED AND UNMARKED DEGREES OF NOTEWORTHINESS.

Persons who are technically "noteworthy" are by no means of equal
eminence, some being of the highest distinction, while others barely
deserve the title. It is therefore important to ascertain the amount
of error to which a statistical discussion is liable that treats
everyone who ranks as noteworthy at all on equal terms. The problem
resembles