phenomenon, and it would be by no means a difficult matter to find
plausible arguments in support of each and all of them. But the almost
absolute similarity of conditions under which imprisoned men live
excludes at one stroke an enormous mass of complicating factors, and
reduces the question to its simplest elements. Here are a thousand men
living in the same place under the same rules of discipline, occupied
in the same way, fed on the same materials, with the same amount of
exercise, the same hours of sleep; in fact, with similarity of life
brought almost to the point of absolute identity; no alteration takes
place in these conditions in summer as compared with winter, yet we
find that there are more offences committed by them in the hotter
season than in the colder. In what way, except on the ground of
temperature, is this difference to be explained. The economic and
social factors discussed by us in connection with the increase of
crime do not here come into play. All persons in prison are living
under the same social and economic conditions in hot weather as well
as in cold. The only changes to which they are subjected are cosmical;
cosmical causes are accordingly the only ones which will account
adequately for the facts. Of these cosmical causes, temperature is by
far the most conspicuous, and it may therefore be concluded that the
increase of prison offences in summer is attributable to the greater
heat.

Seeing, then, that temperature produces these effects inside prison
walls, it is only reasonable to infer that it produces similar effects
on the outside world. The larger number of offences against prison
discipline which take place in the hot weather have their counterpart
in the larger number of offences committed against the criminal law
during the same season of the year. The conclusions arrived at with
respect to the action of season are supported by the conclusions