the nature of this attractive force which drains the country to feed the
city population? What has hitherto been spoken of as a single force will
be seen to be a complex of several forces, different in kind, acting
conjointly to produce the same result.

The first readily suggests itself couched under the familiar phrase,
Agricultural Depression. It is needless here to enlarge on this big and
melancholy theme. It is evident that what is called the law of
Diminishing Return to Labour in Agriculture, the fact that every
additional labourer, upon a given surface, beyond a certain sufficient
number, will be less and less profitably employed, while the indefinite
expansion of manufacture will permit every additional hand to be
utilized so as to increase the average product of each worker, would of
itself suffice to explain why in a fairly thickly populated country like
England, young labourers would find it to their interest to leave the
land and seek manufacturing work in the cities. This would of itself
explain why the country population might stand still while the city
grew. When to this natural tendency we add the influence of the vast
tracts of virgin, or cheaply cultivated soil, brought into active
competition with English agriculture by the railways and steamships
which link us with distant lands in America, Australia, and Asia, we
have a fully adequate explanation of the main force of the tide in the
movement of population. After a country has reached a certain stage in
the development of its resources, the commercial population must grow
more quickly than the agricultural, and the larger the outside area open
to supply agricultural imports the faster the change thus brought about
in the relation of city and rural population.

§ 4. Nature of the Decline of Rural Population.--It has been shown that
the absolute reduction in the number of those living in rural districts