reduces the
average by 0.5 to 1.0 child.

The table given shows clearly what stocks are maintaining, what
increasing, and what diminishing their numbers.

This subject has been investigated recently in a rather extensive way
by David Heron, for the London population. Heron concentrated his
attention upon the relation of fertility in man to social status. He
used as indices to social status such marks as the relative number of
professional men in a community, or the relative number of servants
employed, or of lowest type of male laborers, or of pawnbrokers; also
the amount of child employment pauperism, overcrowding in the home,
tuberculosis, and pauper lunacy. Twenty-seven metropolitan boroughs of
London were canvassed on these bases, which are certainly significant,
though not infallible, indices to the character of a community. His
results are shown in the briefest possible form in Table III.

TABLE III

_Correlation of the Birth Rate with Social and Physical Characters
of London Population._ (From Heron.)

CORRELATION
COEFFICIENT.
With number of males engaged in professions -.78
With female domestics per 100 females -.80
With female domestics per 100 families -.76
With general laborers per 1,000 males +.52
With pawnbrokers and general dealers per 1,000 males +.62
With children employed, ages 10 to 14 +.66
With persons living more than two in a room +.70
With infants under one year dying per 1,000 births +.50
With deaths from pulmonary tuberculosis per 100,000
inhabitants +.59
With total number of paupers per 1,000 inhabitants +.20
With number of lunatic paupers per 1,000 inhabitants +.34

This table gives the results of the calculation of coefficients of
correlation between the birth rates and the conditions enumerated. We
may just recall that this coefficient is a measure of the regularity
with which the changes in two varying conditions or phenomena are
associated: and further that a coefficient of 1.0 indicates perfectly
regular association, 0.75 a very high degree of regularity. The first
line of the table then, for example, means that when these
twenty-seven districts were sorted out, first, with refe