uickly into the lethargy from which it has never recovered. It may be
noted that here, as in the case of Rome, the decay of population and
energy followed a great influx of plundered wealth. On the other hand,
the increase of population in our newly-planted North American colonies
must have been extremely rapid for two or three generations.

The enormous multiplication of the European races since the middle of
the eighteenth century is a phenomenon quite unique in history, and
never likely to be repeated.[16] It was rendered possible by the new
labour-saving inventions which immensely increased the exports which
could be exchanged for food, and by the opening up of vast new
food-producing areas. The chief method by which the increase was
effected, especially in the later period, has been the lengthening of
human life by improved sanitation and medical science.[17] Since 1865
the average duration of life in England and Wales has been raised by a
little more than one-third. Other European countries show the same ratio
of improvement. This astonishing result, so little known and so seldom
referred to, was bound to have a great effect on the birth-rate. So long
as the swarming period continued at its height, a net annual increase of
15 or even 20 per thousand could be sustained; but the expansion of the
European peoples has now passed its zenith, and a tendency to revert to
more normal conditions is almost everywhere observable. One of the most
advanced nations, France, has already reached the equilibrium towards
which other civilised nations are moving. The old-established families
in the United States are believed to be actually dwindling.

The student of international vital statistics will be struck first by
the very wide differences in the birth-rate of different countries. He
will then notice that the more backward countries have on the whole a
considerably higher birth-rate than the more advanced. Thirdly, he will
observe the parallelism between the birth-rate and death-rate, which
makes the net increase in countries with a high birth-rate very little
larger than that of countries with a low birth-rate. The following
figures will illustrate these points; they are taken from the
Registrar-General's Blue Book for 1912.

Birth-rate Death-rate Net rate of
increase
United Kingdom 23.9 13.8 10.1
Australia 28.7