mber of
years, and if we take any period of six years it is remarkable to
observe the unfailing regularity with which crime begins to decrease
as soon as the summer is over and the temperature begins to fall. From
the month of October till the month of February in the following year,
the prison population continues almost steadily to diminish; from the
month of February till the month of October, the same population,
allowing for pauses in its progress and occasional deflections in its
course, mounts upwards with the rising temperature. According to the
last sextennial diagram of the Prison Commissioners, which embraces
the six years ended March, 1884, the mean number of prisoners in the
local prisons of England and Wales was, on the first Tuesday in
February, 17,600; on the first Tuesday in April it had risen to
18,400; on the first Tuesday in July it had reached nearly 19,000; on
the first Tuesday in October it culminated in 19,200. From this date
onwards the numbers decreased just as steadily as they had previously
risen, reaching their lowest point in February, when the upward
movement again commenced. The steadiness and regularity of this rise
and fall of the prison population, according to the season of the
year, goes on with such wonderful precision that it must proceed from
the operation of some permanent cause. What is this permanent cause?
Is it economic, social, or climatic?

Is it economic? It is sometimes asserted that the increase of crime in
the summer months is due to the large number of tramps who leave the
workhouses after the winter is over and roam the country in search of
employment. Many of these wanderers, it is said, are arrested for
vagrancy; in summer they swell the prison population just as they
swell the workhouse population in winter. This explanation of the
increase of crime in summer contains so many elements of probability,
that it has come to be rather widely accepted by students of criminal
phenomena. It has not, however, been my good fortune to meet with any
facts or statistics of sufficient weight to establish the validity of
this explanation. As far as I can ascertain it is an explanation which
has obtained currency almost entirely through its own intrinsic
probability; it is believed, but it has not been proved. Let us
proceed to put it to the test. For this purpose we shall select the
county of Surrey--a fairly typical English county, composed partly of
town and partly of country.