It has long been known that the occurrence of insanity follows an annual curve,[163] and though our knowledge of this curve, being founded on the date of admissions to asylums, cannot be said to be quite precise, it fairly corresponds to the outbreaks of acute insanity. The curve presented in Chart 4 shows the admissions to the London County Council Lunatic Asylums during the years 1893 to 1897 inclusive; I have arranged it in two-month periods, to neutralize unimportant oscillations. In order to show that this curve is not due to local or accidental circumstances, we may turn to France and take a special and chronic form of mental disease: Garnier, in his _Folie à Paris_, presents an almost exactly similar curve of the admissions of cases of general paralysis to the Infirmerie Spéciale at Paris during the years 1886-88 (Chart 5). Both curves alike show a major climax in spring and a minor climax in autumn.
Crime in general in temperate climates tends to reach its maximum at the beginning of the hot season, usually in June. Thus, in Belgium, the minimum is in February; the maximum in June, thence gradually diminishing (Lentz, _Bulletin Société Médecine Mentale Belgique_, March, 1901). In France, Lacassagne has summated the data extending over more than 40 years, and finds that for all crimes June is the maximum month, the minimum being reached in November. He also gives the figures for each class of crime separately, and every crime is found to have its own yearly curve. Poisonings show a chief maximum in May, with slow fall and a minor climax in December; assassinations have a February and a November climax. Parricides culminate in May-June, and in October (Lacassagne's tables are given by Laurent, _Les Habitués des Prisons de Paris_, Ch. 1).
Notwithstanding the general tendency for crime to reach its maximum in the first hot month (a tendency not necessarily due to the direct influence of heat), we also find, when we consider the statistics of crime generally (including sexual crime), that there is another tendency for minor climaxes in spring and autumn. Thus, in Italy, Penta, taking the statistics of nearly four thousand crimes (murder, highway robbery, and sexual offences), found the maximum in the first summer months, but there were also minor climaxes in spring and in August and September (Penta, _Rivista Mensile di Psichiatria_, 1899). In nearly all Europe (as is shown by a diagram given by Lombroso and Laschi, at the end of the first volume of _Le Crime Politique_), while the chief climaxes occur about July, there is, in most countries, a distinct tendency to spring (usually about March) and autumn (September and November) climaxes, though they rarely rise as high as the July climax.