rence to the
number of professional men dwelling in them, and then with reference
to their respective birth rates, there was found a very high degree of
regularity (coefficient of correlation = -.78) in the association of
these two conditions--birth rate and number of professional men. Here
is a very close relation, _but_, the sign of the coefficient is
_negative_. The significance of this negative sign is that among the
communities studied those where the number of professional men is the
larger show always, at the same time, the lower birth rates. Coming to
the second line of the table, it seems fair to assume that the number
of servants employed in a district in proportion to the total number
of residents or families there, gives a fairly though not wholly
satisfactory indication of the social character of the community.
Measurement of the actual relation between the proportional number of
servants employed in a community and the birth rate in that community,
gave practically the same result as in the case of the number of
professional men. The more servants employed in a district the lower
its birth rate. Two methods of measuring this relation gave
essentially the same result; comparison of the birth rate with the
ratio of domestics, first to the number of families, second to the
number of females, gave -.76 and -.80 respectively--very high
coefficients and both negative.

But the sign changes and becomes positive when we come to other
comparisons. When we count the relative number of pawnbrokers and
general dealers, of "general laborers" (that is, men without a trade
and without regularity of occupation and employment), of employed
children between the ages of ten and fourteen, of persons living more
than two in a room, when we consider the infant death rate, the death
rate from pulmonary tuberculosis, and the relative number of
paupers,--then we find the signs of the coefficients are all positive,
and on the average the coefficients are more than 0.50--a moderate to
high degree of regularity of the relation. The districts characterized
by the larger numbers of such individuals or by higher death rates of
these kinds, are at the same time the districts where the birth rates
are the higher.

In a word, then, Heron found that the greater the number of
professional men, or of servants employed in a community, the lower
the birth rate--a very high degree of negative correlation. On the
other hand, the more pawnbroke